US3625422A - Multivalve thermostatic bellows steam trap - Google Patents

Abstract

This invention is a steam trap having a thermostatic type of bellows with two or more discharge valves operated by a single bellows. The trap may also have a flexible valve operating bridge.

Description

limited States Palet Inventor App]. No. Filed Patented MULTIVALVE THERMOSTATIC BELLOWS Harold L. Johnson [56] References Cited Southwick Drive, Hereford Estates, P.0- UNITED STATES PATENTS Heremd 3056 1,609,278 12/1926 Barrett June 26 1969 1,625,689 4/1927 Spangler Dec 7 1,971 [344,425 1/1934 Goldkamp... 3,489,349 1/1970 Hilmer et al.

Primary Examiner-William E. Wayner Attorney-Hubert A. Howson 236/56 l37/60l X l37/625.33 X 236/58 STEAM TRAP 7 Claims, 13 Drawing Figs.

ABSTRACT: This invention is a steam trap having a thermo- U.S. Cl 223366/5382, Static type of bellows with two or more discharge Valves Int Cl i J operated by a single bellows. The trap may also have a flexible maidJQZBIIIIIIIIIIIIII""'""'"'IIIIIIIIIIIIIIII 236/58 56 vahcopmfingbfidge I==iEI PATENTEDDEB 7191: 3625422 sum 2 M 3 nvvmv'mn. Harold L. Johnson By his attorney mam PATENIEHIIEI! mn SHEET 3 OF 3 FIG.H

INVENTOR. Ham/d L. Ja/mson By his attorney MULTIVALVE THERMOSTATIC lBELLOWS STEAM TRAP This invention relates to steam traps such as are used with steam-piping systems and steam-using equipment for automatically disposing of the water which fonns when steam condenses, and any air and other gases present. For effecting this disposal all types of steam traps must have a higher pressure on the upstream or inlet side than the pressure on the downstream or discharge side, and provision must be made for keeping this difference of pressure separated except when the trap is discharging.

The invention concerns traps of the thermostatic bellows type, and difi'ers from previously known traps of this type by utilizing two or more discharge valves and discharge orifices. The opening and closing of the orifices can be accomplished by a single bellows. A flexible valve operating bridge also can be provided. This unique construction, together with other features hereinafter disclosed, permits the same trap to be used for very high as well as low steam pressure applications.

Thermostatic traps of the particular classification pertinent to this invention utilize expansible and contractable temperature-sensitive devices known as bellows, which expand and close the traps discharge valves when exposed to steam temperature, but contract and open these valves in response to some desired temperature drop of the condensate and gases below the temperature of the steam. Bellows suitable for this purpose include the convoluted tubular and multiplediaphragm products of several manufacturers which are presently available.

All well-designed traps of this thermostatic bellows type have certain important advantages over traps of other basic types. These advantages include: very large condensate discharge capacity at all pressures; the ability to dispose of large volumes of air and the other gases encountered at all pressures and without requiring auxiliary devices; no change of valves and orifices or other trap parts, and no adjustment required for different steam pressures. Also, some designs are freezeproof when properly installed.

However, experience has shown that traps of the thermostatic bellows type heretofore available have certain disadvantages and are adversely afi'ected by some detrimental operating conditions which can materially shorten the life of the bellows, instigate waterhammer damage to the equipment and piping drained by the trap, and preclude the use of this type trap for high-pressure steam applications. To eliminate these difficulties with bellows traps as they are presently constructed is either impractical or increases their manufacturing cost, thereby adding an economic disadvantage to such traps when compared with the other basic types. The specific conditions responsible for these undesirable results will be explained further along in this specification, in conjunction with the novel features and advantages of the present invention.

The trap herein depicted and described retains all of the recognized advantages of thermostatic bellows traps over the other basic types, eliminates the disadvantages referred to above and avoids or reduces the effect of any objectionable operating conditions. Another object is to provide a construction suitable for both high and low steam pressure service. A still further object is to furnish a trap adapted to the use of comparatively recent improved bellows designs which permit all or most of the linear movement or expansion required for opening and closing the traps discharge valves to be accomplished on the extension side of the bellows free length. Traps made according to this invention can be fabricated at a cost below other traps of the thermostatic bellows type.

In the drawings I have shown two embodiments of the invention. One version has two discharge valves, intended for traps suited to small and medium pipe sizes. The other embodiment has three valves, intended for traps made to suit the requirements for large pipe sizes. Opening and closing of the valves of both embodiments can be accomplished by a single bellows. A valve operating bridge contoured to accommodate the number of valves used is a feature of each embodiment. In the drawings:

FIG. 1 is a sectional view in elevation, taken on the line 1- I of FIG. 2, of a two-discharge-valve embodiment of my invention showing the bellows in normal contracted position with the discharge valves of the trap wide open.

FIG. 2 is a plan view of the two-valve construction of FIG. I, the one ll showing the line on which the section of FIG. 1 is taken, with the inlet housing omitted in order to show the valve operating bridge and the valve retaining wire. FIG. 3 is a view partly in section showing the center of the trap of FIG. I, with the bellows in normal expanded position and the discharge valves in closed position.

FIG. 4 is a view similar to FIG. 3 of the embodiment of FIG. 1, showing the bellows at free length position and the discharge valves in the normal operating open position.

FIG. 5 is a view similar to FIG. 3, through the center of the assembly of the trap of FIG. 1, showing the bellows extended beyond the normal expanded position of FIG. 3, with the discharge valves closed and the valve operating bridge bowed or deflected downward.

FIG. 6 is a detail view showing a portion of the center of the trap of FIG. 1, illustrating a modified form of means for seating the discharge valves.

FIG. 7 is a plan view of the valve operating bridge for a three-discharge-valve embodiment of my steam trap, the head of one of the discharge valves and a modified form of valve retaining wire being shown on one of the arms of this bridge.

FIG. 8 is a detail view of the wire intended for retaining the valve of the embodiment of FIG. 7.

FIG. 9 is a view in elevation of the exterior of my steam trap.

FIG. 10 is a plan view of the exterior of the steam trap shown in FIG. 9.

FIG. 1 1 is a fragmentary diagram on an enlarged scale, showing a sectioned portion through one valve and its mating orifice seat in the mounting plate of the two-valve embodiment of FIG. I. It will be noted that the seating portion of this valve is on the downstream side of flow through the orifice.

FIG. 12 is a fragmentary diagram on an enlarged scale, showing a sectional portion through a 60 included angle conical valve and its mating orifice seat, as used in some presently available thermostatic bellows traps. It will be noted that the seating portion of this valve of the prior art is on the upstream side of flow through the orifice.

FIG. 13 is a fragmentary diagram on an enlarged scale, showing a sectioned portion through a spherically radiused valve and its mating orifice seat, as used in some presently available thennostatic bellows traps. It will be noted that the seating portion of this valve of the prior art is on the upstream side of flow through the orifice.

Referring to the drawings, the two embodiments of my trap shown herein have a two-piece enclosure or housing, comprising an inlet or upstream section 11 and a discharge or downstream section 12. Housing sections 11 and 12 are furnished with internally threaded openings 28 and 29, axially aligned, for connecting to the condensate drainage piping of the system to be drained. A tubular projection 30 at the bottom of inlet section 11 mates with a cylindrical counterbore 311 in discharge section 12, which conjointly establish and maintain reasonable and acceptable coaxial alignment of the openings 28 and 29. Inlet section 11 includes an integral circular ring 32 having a flat surface 33 against which a corresponding internal flat surface of a clamp nut 13 abuts, for fastening the two housing sections 11 and 12 together, as shown by FIGS. 1 and 9.

The housing discharge section 12 has a concentric external thread 34 which mates with the corresponding internal thread of clamp nut 13, for fastening the housing sections as described above.

Although openings 28 and 29 in housing sections II and 12 are shown as standard female pipe threads, it will be recognized that these housing sections could readily be made with any of the other commonly used means for installing in a condensate piping system, such as by flanged, socket weld, solder joint or tubing connections.

The clamp nut 13 is depicted as being of octagonal contour in FIGS. 2 and 10, but it could also be hexagonal, or circular with a quantity of equispaced longitudinal slots in its periphery to accommodate a standard spanner wrench. Further, clamp nut 13 and those portions of housing sections 11 and 12 intended for the utilization of this nut may be dispensed with, and these housing sections fabricated with mating flanges for connecting together by means of bolts or studs and nuts.

A mounting plate 140 is indicated as a circular metal stamping containing openings or orifices 35. Two of such orifices 180 apart and equidistant from the axis of the plate are used for the dual-valved embodiment of this trap. Three such orifices 120 apart and equidistant from the axis of the plate are used for the triple-valved version.

As shown in FIGS. 1, 3, 4 and 5, the orifices 35 may be stamped and drawn to the bellmouthed nozzle conformation indicated, by utilizing the well-known progressive die production method. By using corrosion-resistant material suitable for hardening, either by cold working or heat treatment, as the metal from which the mounting plate 14a is stamped, the radiused concavity of these nozzles will serve as the seats for the spherical portion 36 of discharge valves 19, as shown in FIG. 3.

An alternate method of providing suitable seats for the valves is depicted in FIG. 6. Here, a mounting plate 14b is fabricated as a flat stamping with cylindrical stamped openings 37, in which the tubular barrels 39 of valve seats 38 are inserted. The valve seats 38, made of hardenable corrosion-resistant material, are formed with bellmouthed orifices 40 and circular flanges 41, each of these latter elements being concentric with barrel 39. As part of the periphery of each flange 41 an integral narrow ring 42 is formed, raised slightly above the surface of the flange which contacts plate 14b. These rings 42 are the means whereby valve seats 38 are attached to plate 14b by the projection resistance welding technique, to provide a pressuretight seal between plate 14b and valve seats 38.

Included also with mounting plates 14a and 14b is an axially centered circular stamped opening 43 in the plates, through which the threaded stem 49 of bellows end fitting 24 is inserted at assembly.

Mounting plate 140 or 14b, whichever is adopted, will be seated on the bottom surface of the cylindrical counterbore 31 in housing discharge section 12 when the trap is assembled. The plate then divides the chamber which results from the joining of housing inlet and discharge sections 11 and 12 into two compartments 44 and 45, as shown in FIG. I. With the trap in service, this plate, in conjunction with discharge valves [9, completely isolates these compartments from each other when the operating conditions are such as to completely close valves 19, as illustrated by FIG. 3.

The temperature-responsive bellows assembly 16 consists of one or more convolutions or sections 22, an upper end fitting 23 and a lower end fitting 24. The convolutions or sections 22 can be any of the hydraulically formed or rolled tubular designs in common use, or may be fabricated from separate diaphragms or circular rings, each of which is suitably welded at its outer periphery to the diaphragm adjacent on one side, and at its inner periphery to the diaphragm adjacent on the other side.

The contour of bellows convolutions or sections 22 in the various drawing figures does not delineate any particular bellows design, but indicates only the expansion and contraction of the bellows as it responds to the conditions imposed on it during trap operation.

Upper end fitting 23 of bellows assembly 16 has a circular flange 46 adaptable for leakproof coaxial fastening to the uppermost of convolutions 22 by any of several methods known to the fabricators of bellows. This flange is spherically radiused 50 at its top periphery in order to prevent a sharp line contact with the lower surface of valve operating bridge 17 or 25, when certain operating conditions induce deflection of the bridge as shown in FIG. 5.

Upper end fitting 23 is provided with a cylindrical stem 47 coaxial with flange 46 and convolutions or sections 22, which locates and limits lateral movement of the valve operating bridge 17 or 25.

Lower end fitting 24 of bellows assembly 16 has a flange 48 adaptable for leakproof coaxial fastening to the lowermost of convolutions 22 and a threaded stem 49 which is a reasonably close fit in opening 43 of mounting plate or 14b, for locating and limiting lateral movement of bellows assembly 16 and the other functional parts of the trap, and for rigidly fastening the bellows assembly to the mounting plate by means of threaded nut 21.

There is a valve operating bridge for the dual-valved embodiment of this invention identified by numeral 17 in FIGS. 1, 2, 3, 4 and 5; the bridge for the triple-valved version is identified by the numeral 25 in FIG. 7. It is intended that these bridges shall be fabricated from material with elastic or spring properties, either inherent or endowed, when desired, and are shown as formed or stamped flat beams with a central hub 26 from which cantilever arms 51 extend laterally. The two arms for bridge 17 are shown apart in plan in FIG. 2. The three arms for bridge 25 are shown l20 apart in plan in FIG. 7.

There is a circular opening 52 in the hub 26 at the axis of each of these bridges. It preferably is a reasonably close fit with stem 47 of the fitting 23 at the upper end of the bellows (see FIGS. 2, 3 and 7.) At the extremity of each cantilever arm 51 a slot 53 is centrally disposed for positioning a valve 19, of which the diameter of the cylindrical stem 54 approximates the width and radius of the slots 53. Additionally, each arm of bridge 25 of the triple-valved embodiment, shown in FIG. 7, is provided with holes 56 sized and located to pennit the insertion of a valve retaining wire 27.

The discharge valves of these traps are indicated by numeral 19, and each consists of three portions of basic shape. First, there is a spherically radiused portion 36 which seats on a bellmouthed orifice 35 of plate 14a or 40 of valve seat 38, for stopping the flow of pressure fluids through the orifice when the operating condition so necessitates. Secondly, there is a circular disc-shaped head 55, the flat bottom surface of which contacts the upper surface of a valve operating bridge arm 51 for positioning the valve in the wide-open, closed, or partially open positions, shown respectively in FIGS. 1, 3 and 4, as determined by the operating conditions. Thirdly, a cylindrical stem portion 54 integrally connects the spherical portion 36 and head 55. The diameter of head 55 is intended to be slightly smaller than the minimum opening through orifice 35 in mounting plate 140 or orifice 40 of valve seat 38, to permit assembly.

In FIGS. 1, 2, 3, 4 and 5, which depict the dual-valved trap, the heads 55 of valves I9 are supplied with a circular hole 57 at a right angle to and through the valve axis, intended for the insertion of a valve retaining wire 18 when assembling the trap.

The valve retaining wire indicated by numeral 18 is, of course, suitable only for the dual-valved trap, as shown in plan in FIG. 2; whereas the wire 27, shown in plan by FIG. 7 and in elevation by FIG. 8, may be used for both the dual and triplevalved designs, if desired. The purpose of both retaining wires is twofold and the same-to maintain reasonable vertical alignment of the axis of valves 19 with the axis of bellows assembly l6 and to prevent the valves from escaping out of the open ends of slots 53 after assembly, while still permitting a small amount of axial movement.

To utilize valve retaining wire 27 with the dual-valved trap it will be obvious that circular hole 57 through heads 55 of discharge valves 19 will be unnecessary, while circular holes 56 will be required in the two cantilever arms SI of valve operating bridge 17 The only advantages incidental to retaining wire 18 are the need for one wire instead of two, and the provision of two holes for insertion of the wire, one through each valve head, compared with four holes for wire 27, two each at the ends of the cantilever arms.

It is intended that both valve retaining wires 18 and 27 be fabricated with their two ends 58 straight, as shown by dot and dash lines in FIGS. 2 and 8. These ends are to be bent at trap assembly as shown by full lines in these figures, after insertion through holes 56 or 57, to insure that these wires remain in place.

FIGS. 1, 2, 3, 4, 5 and 6 picture the dual-valved embodiment of this trap. The only differences between the dual and triple-valved versions are: the quantity of valves needed; the quantity and spacing of orifices 35 in mounting plate 14a or openings 37 in mounting plate 14b; the quantity of valve seats 38 for plate 14b; and different valve operating bridgesl7 in FIG. 2 for the dual-valved trap, 25 in FIG. 7 for the triplevalved version. For purely illustrative purposes it was not deemed necessary to provide additional drawing figures for the triple-valved design, in the belief that the readily discemible variations between the bridges, as depicted in FIGS. 2 and 7, together with the detailed description herein provided, amply distinguishes between the traps.

More than three valves for one trap is neither mechanically sound or economically warranted. Two or three valves 19 will always seat tightly on bellmouthed orifices 35 or valve seats 38 without necessitating extremely close and accurate dimensions and tolerances for the length of the valves or of the other trap parts, by virtue of the fact that the convolutions or sections 22 of bellows assembly 16 are flexible members which readily accommodate reasonable amounts of the axial and/or angular misalignment which could result from variations in the length of the valves. In fact, bellows convolutions with suitable end fittings are frequently used as flexible couplings for misaligned shafts.

ASSEMBLY It should be noted that convolutions or sections 22 and end fittings 23 and 24 will be preassembled, the fluid or combination of fluids for actuating the bellows injected, and the opening for inserting such actuating media hermetically sealed, by methods known to those skilled in the art of fabricating and utilizing such bellows. These operations will result in the formation of bellows assembly 16 as it is used in the traps of this invention, and which will then be in the normal contracted position shown in FIG. 1.

Assembly of these traps is quite simple. First, a ring gasket of suitable compressible material is placed on mounting plate 140 (or 1411) coaxial with opening 43 in the plate. The threaded stem 49 of bellows end fitting 24 is entered through the openings in the gasket and plate, and the bellows assembly rigidly fastened to the mounting plate by means of threaded nut 21. Gasket 20 prevents leakage of the fluids under pressure in compartment 44 of housing inlet section 11, past the flange 48 (FIG. 6) of bellows end fitting 24 and the mounting 1 plate, to compartment 45 of housing discharge section 112.

Next, valve operating bridge 17 or 25, according to the embodiment being assembled, is seated on the top surface of flange 46 of bellows end fitting 23. The heads 55 of discharge valves 19 are inserted through orifices 35 (or 40) and the stems 54 (FIG. 3) of these valves placed in the slots 53 of the valve operating bridge, with heads 55 resting on the top surface of the bridge, as shown in the drawings. The ends 58 of valve retaining wire 18 or wires 27, (depending on the design adopted) are entered through holes 57 in the valve heads 55, or holes 56 in the cantilever arms 51l of the bridge, and these ends 58 bent with a pliers, as shown by full lines in FIGS. 2 and 8. This completes assembly of the functional parts of the traps.

This functional assembly is then seated on the flat surface at the bottom of counterbore 31 in housing discharge section 12. A ring gasket 15 of compressible material suitable for sealing compartment 44 against the escape of fluids under pressure is placed in counterbore 3] and seated on the upper surface of the mounting plate. Tubular projection 30 of housing inlet section 11 is entered into the counterbore 31 until it rests on inlet section 111 and engaged with threaded portion 34 of housing discharge section 12 until, by exerting force on the flat surface 33 of integral circular ring 32, it has been tightened enough to put sufficient pressure on the bottom of counterbore 31, the mounting plate, the gasket 15 and the bottom surface of tubular projection 30, to prevent leakage of fluids under pressure from inside the housing. The trap is then completely assembled.

It will be obvious that an additional gasket 15 may be placed between the bottom of the mounting plate and the flat surface at the bottom of counterbore 31, if deemed necessary, without otherwise changing the construction as shown or affecting trap operation. or a leakproof metal-to-metal joint could be provided between the mounting plate and the inlet and discharge sections of the housing, suitably contoured to effect a pressuretight seal without requiring gaskets. But these are engineering details of construction which are known to and can readily be supplied by those skilled in the art to which this invention is applicable.

INSTALLATION To install the trap, inlet pipe-threaded opening 28 is connected by a pipe or conduit (not shown) to the condensate drainage location of steam-conveying piping or a unit of steam-using equipment, and discharge pipe-threaded opening 29 is similarly piped (also not shown) to a condensate return system or to some other preferred discharge location. Although not absolutely essential, all types of steam traps should be installed below the equipment or piping drained, when feasible, so the condensate can flow to the trap by gravitation.

Also, the traps of this disclosure should be mounted vertically whenever possible, as shown in the accompanying drawings. When steam is turned off and the trap cools, the temperature-sensitive bellows l6 will return to the normal contracted position and the discharge valves 19 will open wide, as shown in FIG. ll. Vertical installation will then permit substantially all of the condensate to drain from the equipment and piping to which the trap is connected, thereby preventing freezing damage when the application is subjected to low ambient temperature. Vertical mounting will also prevent the corrosion which becomes a possibility whenever condensate is permitted to collect and remain in tubes, coils, jackets, piping, etc.

OPERATION The operating principle of thermostatic bellows steam traps is as follows: I have stated that a bellows is a thermosensitive device which, in a steam trap, responds to a temperature differential between the steam and any condensate and noncondensables present in the trap for actuating the bellows. Actuation of the bellows, in turn, effects opening and closing of the trap discharge valve (or valves of the traps herein described). I have also explained that the bellows end fittings are adapted for leakproof fastening to the bellows convolutions or sections, and that the convolutions and end fittings can be preassembled, a suitable fluid medium for actuating the bellows inserted, and the opening for insertion of this medium hermetically sealed, whereupon the combination becomes a bellows assembly, such as that exemplified by the number 16 in my drawings.

The actuating medium chosen by the bellows fabricator will be a fluid, or mixture of fluids, which will generate a certain pressure inside of the bellows when its outside is partly or completely enveloped by another fluid at some specified pressure and temperature, such as steam.

From the above it will be evident that, after the filling medium is injected and the passage for such injection is sealed, the bellows becomes a closed chamber, and its operation in all contemporary thermostatic bellows traps, including this ingasket 15. Then, clamp nut 13 is brought down over housing vention, is analogous to a reversible process steam boiler.

For the traps of this invention, when the steam is turned off and the trap is cold, the bellows 16 will be in the normal contracted condition with discharge valves 19 wide open, as shown in FIG. 1. When the steam is turned on, any air which collected in the piping and equipment served by the trap while the steam was turned off, together with the usually considerable volume of condensate which forms when steam contacts cold surfaces, will enter upstream compartment 44 in the housing inlet section 11 by way of inlet opening 28, pass through orifices 35 (or 40) to downstream compartment 45 in the housing discharge section 12, then through discharge opening 29 to the condensate return or disposal system.

This initial amount of condensate and noncondensables is termed the "warm up load." During most of the time required for discharging this volume the pressure of the steam in the equipment, piping and trap will be low. As the temperature in the system rises and approaches that of the steam, the pressure will also rise, less steam will be condensed, and the diminishing volume of condensate will also approach steam temperature. Eventually, this decreasing amount of condensate will be insufficient to keep compartment 44 in housing inlet section 11 filled, and some steam will enter this compartment with the residual condensate, which will then be at or very close to live steam temperature.

When this incoming steam contacts the convolutions 22 of bellows 16 some of its heat energy will almost instantly be transmitted by conduction through the comparatively thin metal of the convolutions to the actuating medium sealed therein. This heat energy will raise the temperature of the medium, thereby increasing the pressure inside the bellows, which, when the pressure has risen sufficiently, will cause the bellows to expand and the valves 19 to close, as shown in FIG. 3.

For accomplishing this expansion of the bellows and closure of the valves, the actuating medium sealed inside the bellows 16 must generate a final internal pressure equivalent to the combined effect of the forces caused by: (a) The pressure in upstream compartment 44 acting on the external effective area of the bellows; (b) this same pressure operating against the total area of the circular lines of contact between the spherically radiused portion 36 of valves 19 and orifices 35 (or 40) when the valves are closed, as shown by FIG. 3; (c) plus the spring effect of the bellows between its free length at the normal operating open position shown in FIG. 4, and its normal expanded length depicted in FIG. 3; (d) and a small amount of excess pressure over that necessary to merely balance the total effect of forces (a), (b), and (c) to insure tight closure of discharge valves 19.

The advantage of utilizing an actuating medium which will satisfy the above requirements, combined with the very rapid response of the bellows to the conduction of heat energy from the steam, is evidenced by the speed with which this bellows attains its normal expanded length and closes valves 19, as shown in FIG. 3, before all of the residual condensate has been discharged from the upstream compartment 44, thereby preventing the passage and waste of live steam from this compartment to the downstream compartment 45 and the discharge system.

Condensation of steam is continuous in the equipment and piping drained by the trap and, therefore, with valves 19 closed, the condensate level will rise and fill the upstream compartment 44 by displacing and/or condensing the steam which entered this compartment toward the end of the previous discharge cycle. When the condensate is no longer in contact with steam in this compartment it will lose heat energy by conduction and convection through the walls of housing inlet section 11 to the ambient air and through mounting plate 14a (or 14b); also by heat loss through the piping which connects the inlet opening 28 to the system, provided the condensate is generated at a rate sufficient to fill compartment 44 in a very short period of time and starts to rise in this inlet pipe.

It is a well-known law of thermodynamics that when a liquid loses heat energy its temperature will drop. Thus, as the condensate in compartment 44 loses heat, as explained above, its temperature will quickly fall below the temperature of the actuating medium inside bellows l6, whereupon the heat transfer direction will be reversed. In this case, heat energy will flow by conduction from the medium through the thin metal convolutions to the condensate in which bellows 16 is immersed, which will lower the temperature and pressure of the actuating medium. When sufficient heat has been transferred in this manner, the pressure of the medium will have dropped to a point where the pressure in upstream compartment 44, acting on the bellows external effective area, and on the total area of the circular lines of contact between spherically radiused portion 36 of valves 19 and orifices 35 (or 40), together with the force generated by spring effect of bellows 16 when in the expanded position of FIG. 3, can move the bellows to its normal operating open position, opening the valves as shown in FIG. 4, with consequent discharge of the condensate from compartment 44 and the inlet piping.

When this collected condensate has been discharge to the level where live steam can again enter compartment 44 and contact the convolutions 22 of bellows 16, expansion of the bellows and closing of the valves 19 will be repeated, as detailed above. So long as steam is supplied to the system which the trap is draining, the alternate filling and discharging cycles just described will continue. When the steam is shut off, the trap will cool to ambient temperature and the bellows 16 will again attain its normal contracted position with valves 19 wide open, as shown in FIG. 1.

In the forepart of this specification I stated that thermostatic bellows traps heretofore available have certain disadvantages and are adversely affected by some operating conditions. This combination often instigates detriment to these prior traps and to the equipment and piping which they drain. Immediately following that statement I listed the objects of the multivalved traps herein specified and described.

These disadvantages and troublesome conditions will now be explained, followed by a detailed interpretation of the novel features of this invention which provide attainment of the objects. First, however, for an understanding of why currently available traps of the thermostatic bellows type react unfavorably to certain operating conditions, it is necessary to summarize some of the requirements for efficient steam trapping, and for the design criteria applying to such traps, which are at least partially responsible for the undesirable results experienced.

I also stated in the forepart of this specification that all welldesigned thermostatic bellows traps have the advantages of large condensate discharge capacity, and require no change of the discharge valve and its orifice for difierent steam pressures. Large capacity at all pressures necessitates a large unrestricted discharge orifice area.

Furthermore, for most steam trap applications it is imperative that the condensate be discharged at a temperature as close as possible to the temperature of the steam. To satisfy this requirement it is essential that the previously explained temperature drop of the actuating medium inside the bellows, which will be determined by the pressure drop necessary therein for opening the discharge valve (or valves), be kept as low as is practically feasible.

Additionally, presently manufactured bellows traps have just one discharge valve and orifice, with this valve located on the upstream side of fiow through the orifice.

Also, most coexisting traps of this type utilize a bellows which accomplishes opening and closing of the discharge valve with all required linear movement, or expansion and contraction of the convolutions, obtained entirely on the compression side of the bellows free length.

The requirements and circumstances listed in the preceding four paragraphs necessitate that these contemporary singlevalved traps utilize bellows which have a high ratio of the product of mean diameter and span to convolution metal thickness, or by formula: R=M Sl T, where R is the ratio, M is the mean diameter, S is the span and T is the convolution metal thickness. The mean diameter M="-(D-l-d)/2 and the span S=(Dd)/2, where D is the outside diameter of the bellows convolutions and d the inside diameter. Therefore, a bellows which must have a high ratio, and which is limited by space and economic considerations to a reasonable maximum outside diameter, will have thin-walled convolutions in relation to its mean diameter and span. Proof of this need for high ratio bellows with heretofore-obtainable traps of this basic type is provided further along in this specification, in number (4) of the sections which describe the novel features of my multivalved traps.

Moreover, to make certain the entire large area of the discharge orifice of a single-valved bellows trap is useable, its valve must be lifted off the orifice seat to a considerable height, the amount depending on the orifice diameter, the geometric shape of the valve, and the method used to adapt the orifice for seating the valve.

Still further, many steam traps which are in continuous 24- hour service open their discharge valves, and therefore expand and contract their bellows, well over 1,000,000 times a year. Because the maximum recommended linear movement or deflection per convolution of a practicable steam trap bellows is small in relation to the required valve lift explained in the preceding paragraph, it is essential that the quantity of convolutions employed be sufficient to inhibit premature fatigue failure. The spring rate of such a high ratio bellows with many convolutions will be comparatively low and its length over the convolutions large in comparison to its mean diameter.

The following paragraphs describe the adverse operating conditions which can be detrimental to thermostatic bellows traps, and how the above-cited prerequisites for satisfactory steam trapping, and for the design of the heretofore available single-valved traps of this type, contribute to the difficulties encountered. A capital letter, (A) to (F), will precede such explanation of the disadvantages and operating conditions, to reduce the need for repetition when specifying how the features of the multivalved traps of this invention surmount these detrimental conditions.

A. Severe and/or repetitive waterhammer shocks can col- 1 lapse or distort the convolutions of contemporary trap bellows, rendering them inoperative and necessitating replacement.

lt should be noted that, although this detrimental condition is responsible for many of the failures which have plagued heretofore available bellows traps, for many trapping applications the elimination of waterhammer is frequently impractical and occasionally impossible, therefore an attempt must be made to adapt such traps for withstanding it.

Some of the circumstances which instigate waterhammer are: too rapid opening of the steam supply valve; neglecting to pitch piping in the direction of flow; untrapped risers and low spots in steam supply piping; vacuum breakers not installed where their use is indicated; hot steam contacting cool condensate; condensate return piping too small for the volume of water and flash steam it must handle; lifting condensate to a higher level after its discharge from a trap.

B. On high pressure applications a sudden drop of steam pressure results in a high unbalanced pressure inside the bellows. This occurrence frequently causes failure of the bellows supplied with presently available traps of this type by rupturing or permanently deforming the convolutions.

Reasons for this sudden pressure drop include: too rapid closing of the steam supply valve; a large influx of cold material to a process vessel drained by the trap; a sudden increase of steam demand too large for the supply piping or boiler to satisfy immediately; bursting of a coil, jacket, chamber or chest of the equipment drained, or of the steam supply piping.

C. Except at very low steam pressure, most coexisting bellows traps have an abrupt break of the discharge valve off its orifice seat at the instant of discharge, and an immediate considerable lift of the valve afier this breakoff." Frequent unexplained failure of the bellows used with prior traps of this LII type on high pressure applications prompted tests which proved that the suddenness and violence of the action described above incited periodic vibrations of some of the bellows convolutions, the frequency and amplitude of which caused premature fatigue of the metal.

The abrupt "break" of the valve off its orifice seat is evolved as follows:

It has been previously explained that bellows traps heretofore available have valves which operate on the upstream side of the flow through their discharge orifices. When the valve of such a trap is in the closed position, there is an unbalanced force thereon which holds it closed. This force is the resultant of the pressure of the actuating medium inside the bellows, multiplied by the discharge orifice area, plus any spring effect remaining in the bellows convolutions.

Before the discharge valve can open there must be a pres sure drop inside the bellows, the amount being somewhat more than that obtained by converting the total force recorded in the previous paragraph from a pounds basis to pressure per square inch. When sufficient pressure drop has occurred to instigate the break" of the valve off its orifice seat, a force almost equivalent to that above acts oppositely and immediately to cause nearly instantaneous additional compression of some of the bellows convolutions and wider opening of the valve. A hysteretic effect is thereby set up between the different convolutions which too frequently results in bellows failure.

D. Most previously obtainable traps of the bellows type intentionally have the discharge valve attain its closed position with the bellows still on the compression side of its free length. Thus, failure of the bellows for any reason other than the waterhammer condition of (A) causes the convolutions to expand and close the valve, with consequent retention of condensate in the trap body or housing and in the system served by the trap. Unless this failure is quickly discovered and remedial measures promptly instituted, spoilage of material in process may result, and damage to the system can be caused by waterhammer, and by freezing if the ambient temperature is low.

Even those contemporary traps which utilize a bellows extending slightly beyond its free length when the discharge valve is closed have been proved by experience to fail safe" and partially open the valve only when subjected to low steam pressure. Vortex effect and pressure drop in and adjacent to the discharge orifice causes these bellows to expand beyond their free length and close the valve, in event of this kind of failure with these traps when applied to high pressure service.

E. To prevent misalignment of the bellows and discharge valve with the traps discharge orifice, in order to avert dribbling and live steam blowby, the most efficient thermostatic bellows traps presently available require accurate machining and mating of their various parts, and must include some method for maintaining alignment of the bellows and the valve with the discharge orifice. Obviously, this necessity increases manufacturing cost.

The possibility of such misalignment will be easier understood by recalling two previously stated facts; (I That the convolutions of bellows are flexible members which are frequently utilized as flexible couplings, and; (2) that traps of the bellows type currently obtainable have a discharge valve which seats on the upstream side of flow through its orifice, which means that, when this valve is closed, the bellows will be pushing against an unyielding solid structure. Therefore, unless the oblique flexibility of the bellows is reasonably restrained, leakage of condensate and live steam past the discharge valve is probable.

F. With some designs of coexisting bellows traps, particu larly those with a horizontal inlet opening which is low in the trap body or housing in relation to the position of the bellows, when steam enters the trap and causes the discharge valve to close, this steam cannot be displaced by the water which follows. Until some of this locked-in steam condenses the water cannot enter the body and contact the bellows. This condition is known as steam binding, and when it occurs, condensate will back up in the piping and equipment connected to the trap inlet. For high condensing rate applications the result will be sluggish drainage, with probable reduction of equipment efficiency and possible waterhammer damage.

It should now be evident that heretofore available thermostatic bellows traps which need: bellows with a high ratio of the product of mean diameter and span to convolution metal thickness; plus a large quantity of convolutions to ensure that all of the discharge orifice area is useable, with consequent low spring rate and considerable length over the convolutions in relation to its mean diameter; and with all or most of the necessary linear movement or deflection for opening and closing the discharge valve occurring on the compression side of the bellows free length; together with a discharge valve which is situated on the upstream side of flow through the discharge orifice; are predisposed in some measure to the failures and expense resulting from the circumstances set forth in (A) to (F) inclusive.

For the multivalved traps of this disclosure six construction features combine to either prevent or reduce the detrimental effects of any adverse operating conditions encountered and to accomplish the objects sought. A description of these features and an explanation of their merits follows, each preceded by a numeral, l) to (6), for eventual relation to the conditions (A) to (F) previously described.

I. THE UTILIZATION OF MORE THAN ONE DISCHARGE VALVE ACTUATED BY A SINGLE BELLOWS Thermostatic bellows traps currently available are manufactured for standard pipe sizes from three-eighths inch to 2 inches. Naturally, the traps bulk and its discharge orifice area increase as the pipe size increases. As the discharge orifice area is increased, so also must the lift or height of the discharge valve off its orifice seat be increased to ensure that the full orifice area is useable. This is true regardless of the geometric shape of the valve. The use of more than one discharge valve and orifice for a desired total orifice area reduces the required area per orifice, and shortens the valve lift necessary to achieve this reduced area. Reduced valve lift lessens the quantity of convolutions or sections required for the bellows.

FIGS. ll, 12 and 13 of the drawings show this advantage of multiple valves and orifices over two of the single valve and orifice designs utilized for several contemporary thermostatic bellows traps. These figures are to a larger scale than FIGS. 1 to 10, but each has been enlarged in the same proportion, with FIG. 11 representing the dual-valved embodiment of the traps herein specified.

For each of the constructions diagrammed it will be evident that the valve lift which is required to make certain the full orifice area is useable should be the minimum which will provide an area of the cylindrical surface of the frustum of a cone equivalent to the orifice area. In the two-dimensional sectioned diagrams of FIGS. ll, 12 and 13, these conical frustums are represented by trapezoids, with D indicating the major diameter, d the minor diameter, and S the length of the cylindrical surface. Obviously, S should be measured at the closest proximity of the valve to its orifice seat.

The three delineations shown were developed as follows: Starting with an orifice area common to several single-valved contemporary traps of a given pipe size, the diameter of which is shown as dimension in FIGS. 12 and 13, it will be ap parent that diameter X in FIG. 11 for each orifice of my dualvalv'ed trap must be that which will provide an area equivalent to one-half of the area of diameter 0, plus the area of the valve stem indicated by diameter Y in FIG. 11. A comparative mathematical analysis then proved that the lift L1 in FIG. ll necessary to have the area of conical surface of length S equal one-half the area of diameter 0, need be only 32.8 percent of the lift L2 in FIG. 12 necessary to have the area of the conical surface of length S in that figure equivalent to the area of diameter 0, and but 65.4 percent of the lift L3 required by the construction of FIG. 13.

If the triple-valved embodiment of my invention had been represented in FIG. 11, the lift Ll required would then be only 24.4 percent of lift L2, and but 48.6 percent of lift L3.

Interpreting these required valve lifts, L1, L2, and L3, in terms of the quantity of bellows convolutions needed, using bellows of like design, having the same ratio of the product of mean diameter and span to convolution metal thickness, and a percentage of maximum allowable stroke per convolution which would assure long fatigue life under normal operating conditions for all three constructions, the single-valved trap of FIG. 12, with a cone-shaped valve, needs three times as many bellows convolutions as my dual-valved trap of FIG. 11, and four times as many as my triple-valved embodiment, if that version had been shown in FIG. 11.

Although a bellows for the single-valved trap of FIG. 13 with a spherically radiused valve requires fewer convolutions than the bellows for the cone-shaped valve construction of FIG. 12, it still needs 50 percent more than the bellows suitable for my dual-valved trap of FIG. 11, and I00 percent more than the triple-valved embodiment, if that adaptation had been depicted in FIG. 11.

To keep the valve lifi and number of bellows convolutions minimal, it is intended that two discharge valves and orifices be incorporated in the traps of this invention intended for the smaller pipe sizes; three valves and orifices in larger pipe size traps.

2. THE UTILIZATION OF A SPHERICALLY RADIUSED SEATING SURFACE WITH THE MULTIPLE VALVES OF l AND LOCATING THESE SEATING PORTIONS ON THE DOWNSTREAM SIDE OF FLOW THROUGH THE TRAP ORIFICES Spherically radiusing portion 36 of discharge valves 19 assures leakproof seating on orifices 35 (or 40) when the operating condition which causes bellows 16 to expand closes the valves, as shown in FIG. 3, even if there is some angular and/or lateral misalignment of a valve axls with the bellows axis. The probability of such misalignment is enhanced by the detrimental condition which induces considerable deflection or bowing of the valve operating bridge, as shown in FIG. 5.

Thus, spherical radiusing of these valves prevents leakage or blowby of live steam, a costly waste when it occurs on high pressure applications. An additional economic advantage results from the fact that since a reasonable amount of misalignment will not induce steam leakage, it is unnecessary to have the diameter of stem portion 54 of the valves closely fit the width and radius of slots 53 in the cantilever arms 51 of valve operating bridge 17 (or 25).

Operating and seating these valves on the downstream side of their discharge orifices affords the advantages of a nonviolent discharge at all steam pressures, and the lowest practical temperature drop of the condensate below steam temperature to start opening the valves.

The start open temperature drop required is just a fraction of a degree more than that necessary to lower the pressure inside the bellows an amount equal to the excess pressure generated therein for the purpose of insuring tight closure of the valves. This small excess pressure was previously described in that part of this specification which explained the operating principle of these multivalved traps, and was item (d) of the paragraph which listed the various forces requiring counteraction by the pressure of the filling medium sealed inside the bellows.

After the valves start to open, each additional degree of temperature drop of the condensate will result in small increments of further bellows contraction and wider opening of the valves. Thus, the discharge pattern of these traps will vary or modulate with the condensate temperature, with neither abruptness nor violence during the opening and closing cycles.

3. THE UTILIZATION OF BELLOWS WHICH ACCOMPLISI-I THE LIFT L1 OF THE DISCHARGE VALVES WITH TWO-THIRDS OF THE REQUIRED STROKE ON THE EXTENSION SIDE OF THE BELLOWS FREE LENGTH AND ONE-THIRD ON THE COMPRESSION SIDE As shown in FIGS. 1, 3 and 4, these multivalved traps have three principal positions of the discharge valves, each of which, it is intended, will be attained at a specific position of the bellows stroke.

With the valves lifted off their respective orifice seats to the distance L1 in FIG. Ill, which, as previously explained in (1), provides an unrestricted flow area equal to the total orifice area required, the bellows will be at its normal contracted length, in which position approximately 33 percent of the total stroke LI is intended to be on the compression side of the bellows free length. This position of the valves and bellows is illustrated by FIG. l, and is the condition which applies when the trap is cold, with the steam turned off. Thus, maximum orifice area is available for handling the large volume of condensate and noncondensables encountered with most trap installations during the warm up" period, immediately after the steam is turned on.

With the discharge valves closed, the condition which prevails when steam contacts the bellows after the system, equipment and trap are up to operating temperature, and again at the end of each discharge cycle thereafter, the bellows will be at its normal extended or expanded length, in which position approximately 67 percent of the total stroke LI is intended to be on the extension side of the bellows free length. This position of the valves and bellows is shown in FIG. 3.

During trap operation, whenever enough condensate has entered the traps upstream compartment 44, cooled, and absorbed sutficient heat energy from the actuating medium inside the bellows, the latter will contract to its free length, bringing the discharge valves to their normal operating open position, as shown in FIG. 4. In this position the total area past the minimum passages between the spherically radiused portion 36 of the valves and their orifice seats will be approximately two-thirds of the maximum orifice area which is available when the valves are in the cold position of FIG. 1. For the modulating discharge pattern of these multivalved traps this proportion of the total orifice area allows ample hot condensate discharge capacity, and is considerably more than that provided by any heretofore available thermostatic bellows trap for any given temperature drop of the condensate below steam temperature.

The operating conditions which bring about the positions of the bellows and valves related in the three preceding paragraphs were previously explained in that section of this specification which described the principle of operation for these multivalved traps.

Because more than 25 percent of total required stroke on the extension side of free length is not practical for the convolution contours of bellows used in presently obtainable traps of this type, the multivalved traps of this invention have been purposely devised to utilize this advantage of recent developments available from several bellows fabricators. Among the designs which meet the requirements of these traps are at least three of the multiple-we]ded-diaphragm convolution contours designated as nesting ripple," single sweep" and torus types, and the so-called squeezed convolution" seamless bellows formed from tubing. Three of these contours can withstand higher unbalanced pressures than similarly dimensioned bellows of the older convoluted type.

4. THE UTILIZATION OF BELLOWS HAVING A LOW RATIO OF THE PRODUCT OF MEAN DIAMETER AND SPAN TO CONVOLUTION METAL THICKNESS Two of the construction features described in (2) and (3) combine to make feasible, for the traps of this invention, bellows which have a very low ratio of the product of mean i4 diameter and span to convolution metal thickness. These features are: (a) location of seating portion 36 of valves I9 on the downstream side of flow through the trap orifices; and (b) adoption of a bellows design which permits most of the stroke required for opening and closing the valves to be attained on the extension side of the bellows free length.

It is intended that these low ratio bellows shall have a small outside diameter, a narrow span, and convolutions of considerable metal thickness, in comparison to the bellows used with contemporary traps of this basic classification. Such low ratio bellows are completely satisfactory and serve a definite purpose for the multivalved traps herein specified, but there are several reasons why they are not suitable for presently available bellows traps of equivalent pipe sizes. Three of these reasons have been previously mentioned: all of these traps have their single discharge valve situated on the upstream side of flow through the trap orifice; the bellows used accomplishes opening and closing of this valve with all or most of the stroke required obtained from the compression side of the bellows free length; for the majority of steam trap applications it is essential that the condensate be discharged at a temperature as close as possible to the temperature of the steam.

Other reasons are that the low ratio bellows described above will have small effective areas and high spring rates, which, together with the first two reasons of the immediately preceding paragraph, preclude their use in heretofore procurable bellows traps for all but the least important applications. This is so because the mathematical analysis mentioned in (1) proved that, if such low ratio bellows were used, an excessive temperature drop of the condensate below steam temperature would be required just to break" the valve off its orifice seat.

For example, a mathematical comparison of the dual-valved trap of this invention, for which FIG. 111 is a diagram of the discharge valves and their orifices, with a currently available single-valved trap of like pipe size, the valve and orifice diagram of which is shown by FIG. 12, each using the same total discharge orifice area, and bellows of like convolution contour, outside diameter, span and convolution metal thickness, but each having the quantity of convolutions previously determined necessary-in (l)for achieving the different valve lifts required. LI of FIG. 11 and L2 of FIG. 12, gave the following results:

At l00 pounds per square inch gage steam pressure, a temperature drop of 22.3 F. was required just to break the valve off the seat of the contemporary single-valved trap. For my dual-valved trap a temperature drop of 12 F. will open the valves from the closed position of FIG. 3 all the way to the normal operating open position shown by FIG. 4. For higher steam pressures the contrast becomes even more significant. At 300 pounds per square inch, the temperature drops necessary to perform the above operations were 272 F. and 7.2 F., respectively, and at 600 pounds per square inch, 3l.6 F. and 5.5 F., respectively.

These temperatures drop requirements verify a statement made earlier in this specification: that currently available thermostatic bellows traps must utilize bellows which have a high ratio of the product of mean diameter and span to convolution metal thickness, if a large discharge orifice area and acceptable temperature differentials between the steam and condensate;9c are to be attained. For instance, again considering the contemporary single-valved trap of the preceding two paragraphs, same pipe size and orifice area, with discharge valve and orifice as diagrammed in FIG. 12, but with the necessary temperature drop of the condensate to break" the valve off its orifice seat reduced to an acceptable 5 F. below the temperature of the steam at 300 pounds per square inch pressure, a bellows will be required which must have a ratio of the product of mean diameter and span to convolution metal thickness more than three times as large as the ratio which is suitable and intended to be used for equivalent pipe size and orifice area multivalved traps of this invention.

Such low ratio bellows, together with the reduced quantity of convolutions needed, as explained in (1), results in a very rigid bellows with a high spring rate, which resists damage such as collapsing, bursting or permanent deformation of the convolutions, the conditions which are incidental to excessive unbalanced overpressure, either external or internal, with the high ratio bellows required for single-valved currently available bellows traps. In support of this statement, it should be noted that the maximum allowable unbalanced pressure for any bellows will vary inversely as the square of D minus d, where D is the outside diameter of the bellows convolutions and d the inside diameter, and will also vary directly as the square of the convolution metal thickness.

5. THE UTILIZATION OF A FLEXIBLE CANTILEVER- ARMED VALVE OPERATING BRIDGE It is intended that this bridge shall be fabricated from corrosion-resistant material with spring properties. It will then be deflected or bowed slightly when the trap's discharge valves are closed. This bowing or deflection will increase considerably when some operating condition drops the steam pressure suddenly, with consequent increase of unbalanced pressure inside the bellows, as explained in (B).

The resultant additional extension of the bellows beyond the normal expanded position will increase its spring rate force, which, with the spring force of the deflected bridge, will act opposite to and resist the force generated by the excess pressure inside the bellows. The physical effect of these counteracting forces on the bridge, bellows and discharge valves is depicted in FIG. 5.

I do not claim that this bridge will prevent rupture of the bellows convolutions if the unbalanced pressure is extremely excessive. But the bridge is to be formed from flexible material which will yield, and the bellows will therefore be pushing against a nonrigid beam. This will tend to prevent oblique or lateral deformation failure due to stress which otherwise might exceed the elastic limit of the convolution material. Such deformation is the more frequent cause of convolution failure with bellows used in contemporary traps of this classification, which, when subjected to excessive unbalanced internal pressure, will be pushing against a rigid structure consisting of the closed valve, valve seat and trap body section in which the valve seat is fastened or formed.

Traps to this invention intended for low and medium steam pressures only, which utilize bellows having a low enough ratio of the product of mean diameter and span to convolution metal thickness sufficient to safely withstand an unbalanced pressure inside the bellows equivalent to the steam pressure, may have this valve operating bridge fabricated of thicker gage material and without spring properties, if it is so desired.

LOCATING THE TRAP INLET OPENING AT THE TOP OF THE HOUSING OR BODY As shown in FIG. 1, inlet opening 28 is at the extreme top of housing upstream section 11. Also, in the preceding part of this specification which suggested how these traps should be installed, it was pointed out that vertical mounting would provide the best operating results and should be adopted whenever possible.

It will then be apparent that, after the bellows has expanded and the valves have closed, as shown in FIG. 3, the steam which entered upstream compartment 44 of housing inlet section II and caused the valves to close, can be immediately displaced by the higher density condensate as it enters compart' ment 44. Thus, the two features of the preceding paragraph combine to inhibit any possibility of steam binding, a condition which result in sluggish drainage of the condensate, lowering of equipment efficiency and possible waterhammer damage.

The first object of the traps herein specified was to retain the four recognized advantages of well-designed traps of the thermostatic bellows type over the other basic types of steam traps. Two of these advantages are, large discharge capacity at all pressures, and no change of valves and orifices or other trap parts, and no adjustment required for different steam pressures.

The answer here is that, as used in thermostat bellows traps, the bellows is analogous to a piston in a cylinder, the diameter and area of which are equal to the mean diameter and corresponding effective area of the bellows. This means that the force available for opening the trap discharge valves is derived from the steam pressure in the trap, and because the same bellows is used for all pressures in any given pipe size trap, as the steam pressure is increased, the power which opens the valves increases to the same extent. Thus, the chosen orifice area may be retained at all pressures and no change of parts and no adjustment of the trap is necessary for changes of steam pressure. Since the theoretical discharge from a trap orifice varies as the square root of P, where P is the pressure difference across the orifice, large capacity is attained at all pressures.

Another advantage of these traps is their ability to discharge large volumes of air and other noncondensables encountered in most steam systems, at all pressures and without requiring the use of auxiliary devices. Whenever air and/or other gases become mixed with steam, the temperature of the mixture will be less than the temperature of pure steam, the degrees of temperature drop depending on the volume of noncondensables present. Since temperature drop is the circumstance which causes the valves of thermostatic bellows traps to open, it will be evident that they can expel these noncondensables just as efficiently as they discharge condensate.

The fourth advantage cited for some designs of bellows traps, that of being freezeproof when properly installed, is achieved by the previously stated fact that whenever the steam is turned off and the trap cools, the bellows will contract and the valves will open wide, as pictured in FIG. 1.

This figure will show that the traps of this invention have been designed so that substantially all of the condensate can then drain from the upstream compartment 44 to the downstream compartment 45 and then to outlet opening 29, providing the trap has been installed vertically as shown and suggested.

The second object of my multivalved traps was the development of a design which will eliminate the disadvantages of heretofore obtainable traps of the bellows type, and which avoids or reduces the effect of certain detrimental operating conditions. Whether or not the disadvantages inherent in prior traps of this type are overcome by the design herein disclosed must obviously depend on how well the novel features previously explained in (l) to (6) resist the effect of the troublesome conditions which have been previously cited in (A) to (F). A detailed interpretation of how these novel features relate to the various objectionable conditions follows:

The answer of these multivalved traps to the severe and/or repetitive waterhammer shocks described in (A) is provided by a combination of three factors: the intended use of bellows having a low ratio of the product of mean diameter and span to convolution metal thickness, as detailed in (4); the fewer convolutions required for the bellows, resulting from the utilization of multiple discharge valves and orifices, as specified in (l); and the adoption of comparatively new bellows constructions withimproved convolution contours which can accommodate higher unbalanced pressures than the older corrugated designs in common use, as described in (3).

This combination provides strong, rigid bellows having the highest spring rates which are practical for steam trap useage, with exceptional resistance against damage from distortion or collapse of the convolutions when subjected to waterhammer shocks.

For withstanding the high unbalanced pressure inside the bellows resulting from the conditions itemized in (B), the advantages of bellows having a low ratio, fewer convolutions,

and advanced design convolution contours, as intended for the bellows to be used with the traps herein specified, and as defined in (l), (3) and (4), join with the distinct benefit derived from utilization of the flexible valve operating bridge explained in (5) in counteracting this high unbalanced internal pressure and preventing rupture and/or permanent deformation of the bellows convolutions.

The detriment which can result from two unfavorable characteristics common to presently available thermostatic bellows traps is averted with the traps herein specified by the cooperation of two design features.

One of these troublesome factors is the abrupt break" of the discharge valve off its orifice seat, when contemporary traps of the bellows type are applied to high steam pressure service. This sudden opening of the valve instigates a violent discharge of the condensate and possible damage to the bellows. This damage and the functional sequence conducive to its occurrence have been specifically defined in (C).

This difficulty cannot develop in my multivalved traps because, with the seating portion 36 of valves 19 on the downstream side of the discharge orifices, and with these valves closed, as pictured in FIG. 3, the steam pressure in upstream compartment 441 will be trying to force the valves open. Additionally, with the bellows intended for the traps of this invention extended beyond their free length a distance equivalent to approximately two-thirds of the total stroke required for bringing the valves from the wide-open position of FIG. 1 to the closed position of FIG. 3, spring rate force of the bellows will augment the force provided by the aforesaid steam pressure in the opening of my valves. This is just the opposite of the effect of these two forces in bellows traps currently obtainable. as explained in (C).

Thus, the valves of the traps herein specified will not break" suddenly 01? their orifice seats, nor will there be turbulence or violence associated with the discharge of the condensate at any steam pressure. The design features which assure this advantage have been described in (2) and (3).

The other undesirable characteristic of coexisting bellows traps on high pressure installations is the closing of the valve incidental to bellows failure for any reason other than that caused by waterhammer. This is so because of two facts: the discharge valve is located on the upstream side of its orifice; the bellows will still be on the compression side of its free length, or near to free length, when the valve is closed. These design principles for coexisting bellows traps have been previously cited in this specification, and the consequences of such bellows failure referred to in (D).

Here, too, for the traps of this invention, the combination of discharge valves which seat on the downstream side of flow through their orifices, as set forth in (2) and bellows which achieve approximately two-thirds of the total stroke required on the extension side of free length, as pointed out in (3), avoids the possibility of damaging results incidental to bellows failure.

in the event of such failure for any reason, my bellows will immediately return to its free length, bringing the valves to their normal operating open position, as delineated in FIG. 4. Obviously, until this failure is discovered and the bellows is replaced, some live steam will also be discharged with the condensate, but there will not be backup and retention of the condensate in the equipment drained by the trap, with probable production loss and waterhammer, and possible freezing damage if the ambient temperature at the trap location is low.

The multivalved traps of this invention do not require extremely close machining tolerances, accurate mating of the various parts, nor any means for maintaining alignment of the bellows and valves with the discharge orifices, in order to avoid dribbling and the passage of useful live steam. The reasons why these exigencies are needed with the singlevalved bellows traps currently available were stated in (E).

Four design factors of the traps covered by this disclosure combine to obviate the need for any such leak-preventing expedients. These factors are: assembly of all functional parts on one component-the mounting plate 14a (or 14b); the previously noted flexibility of the bellows convolutions, which becomes an asset for my traps, instead of a liability; spherically radiusing seating portion 36 of the discharge valves which assures tight closure despite any reasonable amount of angular or axial misalignment of the bellows and valves, as explained in (2); and the small amount of excess pressure provided by the actuating medium sealed inside the bellows, as referred to earlier in this specification.

Neither can the traps covered by this invention become steam bound, a troublesome condition with some designs of prior thermostatic bellows traps. How this difficulty can occur and its undesirable results have been related in (F).

With inlet opening 28 at the top of upstream housing section 11 and vertical installation as pointed out in (6), steam binding cannot take place in the traps herein specified.

The third project of this invention was the development of a trap suitable for both high and low steam pressure service. It has been hereinbefore shown how certain inherent disadvantages, and some undesirable operating conditions, are conducive to detrimental results with previously obtainable traps of this type. A review of the troublesome conditions defined in (A) to (F) will show that a sudden drop of steam pressure in the trap body, as described in (B), and the abrupt break" of the discharge valve off its orifice seat, as stated in (C), are the two circumstances most likely to instigate serious trap failure on high pressure applications. It will be apparent, too, that the higher the operating steam pressure, the more susceptible contemporary bellows traps will be to such failures.

To achieve this third objective with my multivalved traps, the advantages afforded by a low ratio bellows, as explained in (4); having a high spring rate resulting from the reduced quantity of convolutions required, as derived in l and discharge valves seating on the downstream side of their orifices, as recounted in (2); with the bellows providing approximately two-thirds of the total stroke necessary for operation of these valves obtained on the extension side of its free length, as stated in (3); the beneficial deflection force provided by the flexible valve operating bridge, as described in (5); combine to make the traps of this specification suitable for the highest steam pressure to which the body or housing construction, and the inlet and outlet connections adopted, may be subjected.

Quite obviously, the housing sections 11 and 12 of the embodiments portrayed by the attached drawings can be fabricated of suitable materials, with thickness dimensions, type of inlet and outlet connections, and methods of fastening the two housing sections together, which will be satisfactory for either high or low pressure. All other parts of these traps will perform their intended function without requiring change for any pressure for which these traps are intended.

The fourth object of this invention was to adapt the traps herein specified for utilizing the advantages available from several comparatively new bellows developments.

One of the features which contributes to the high pressure suitability of these multivalved traps, as indicated in the preceding explanation of how the third objective was achieved, is attainable only from some of these modern bellows designs. This feature is their ability to provide all or most of the stroke required for opening and closing the traps discharge valves on the extension side of the bellows free length. This particular attribute is also one of the factors which makes possible the use of bellows having a low ratio of the product of mean diameter and span to convolution metal thickness, another high pressure advantage, as explained in (4).

My fifth object was to effect significant economies in the production of the traps covered by this disclosure. This goal is attained by three factors previously explained or show in the drawings, and by urging the adoption of certain modern materials and high production manufacturing techniques for some of the trap parts.

Two of the cost-reducing features mentioned earlier in this specification are: The fact that these multivalved traps do not require close machining tolerances for the mating dimensions of the various parts, nor any means for maintaining within narrow limits alignment of the bellows, discharge valves and discharge orifice seats; and the ease and speed with which the trap can be assembled.

The third factor, as developed in (l) of the exposition of novel characteristics applying to these traps, is the reduced quantity of convolutions required for the bellows. It is obvious that bellows cost will be related to the number of convolutions necessary, but, for two of the multiple-welded-diaphragm designs referred to in (3), which require twice as many circumferential welds as the quantity of convolutions or sections, it is an important fact that the cost of these bellows decreases almost directly as the reduction in the number of welds.

One of the high production suggestions is depicted in FIGS. 1, 3, 4 and 5 of the drawings, wherein bellmouthed orifices 35 are to be formed in mounting plate 14a at the time this plate is fabricated, thereby obviating the need for separate discharge valve seats and for a means of fastening these seats to the plate. Even if the construction shown in FIG. 6 is chosen, the separate valve seats 38 needed with mounting plate 14b are intended to be fastened to this plate by the projection resistance welding process, a low cost production method.

Also, by referring to FIG. 1, it will be noted that the housing inlet and discharge sections 11 and 12 can be machined from the same casting or cored forging.

I suggest, too, that discharge valves 19 be fabricated by one of several high production operations, such as the lost wax, investment casting, shell mold or ceramic mold techniques, etc. Because of the previously explained flexibility of the bellowsconvolutions, the dimensional tolerances attainable with the above-mentioned processes for the length and diameters of the three basic shape portions 36, 54 and 55, will be satisfactory for these valves. lf proper attention is directed to the tooling and application of whichever of the above methods is chosen, the surface finish obtainable will be such that no additional finishing operations will be required other than lapping of the spherically radiused portion 36 in orifices 35 (or 40).

Further, it will be noted that the mounting plate 14a (or 14b) and the valve operating bridges 17 and 25 can be produced as metal stampings which, if fabricated in progressive dies, are high production processes which will obviate the need for any subsequent machining of these parts. I suggest that the material used for these parts be one of the precipitation-hardening types of stainless steel, which can be heat treated for developing hardness or spring properties where necessary, with little or no resultant distortion.

I claim:

1. A thermostatic steam trap comprising a housing having a chamber therein, a partition dividing said chamber into two compartments, one compartment being provided with an inlet and the other compartment being provided with an outlet, said partition being provided with a plurality of orifices, a valve for each orifice, a single thermostatic bellows mounted in said chamber said orifices lying in a common plane and spaced transversely from the longitudinal axis of said thermostatic bellows, mechanical means extending transversely from said thermostatic bellows connecting said valves therewith so that relatively small movement of said thermostatic bellows will open said valves sufficiently to result in full flow through said orifices.

2. A thermostatic bellows steam according to claim 1, in which the mechanical connection comprises a bridge member between the bellows and the valves which is controlled by the expansion and contraction of the bellows.

3. A thermostatic bellows steam trap according to claim 1, in which the desired maximum opening of the trap for discharge comprises the sum of the areas of the orifices for the multiplicity of discharge valves, whereby the lift required to open each valve completely is reduced.

4. A thermostatic bellows steam trap according to claim 1, in which the mechanical connection comprises a flexible cantilevered-armed beam mounted on the ligper end of the bellows, operating as a bndge between e bellows and the valves, and controlled by the expansion and contraction of the bellows.

5. A thennostatic steam trap comprising a housing having a chamber therein, a partition dividing said chamber into two compartments, one of said compartments being provided with an inlet and the other compartment being provided with an outlet, said partition being provided with a plurality of orifices, a valve for each orifice a single thermostatic bellows mounted in said chamber said orifices lying in a common plane and spaced transversely from the longitudinal axis of said thermostatic bellows, (flexible) means extending transversely from said thennostatic bellows connecting said valves therewith so that relatively small movement of said thermostatic bellows will open said valves sufficiently to result in full flow through said orifices.

6. A thermostatic steam trap comprising a housing having a chamber therein, a partition dividing said chamber into two compartments, one compartment being provided with an inlet and the other compartment being provided with an outlet, a single thermostatic bellows mounted in said chamber, a multiplicity of discharge valves, a cantilever-armed beam mounted on the upper end of the bellows and operating as a bridge between the bellows and the valves to operate said valves, said bridge being flexible and thereby adapted to prevent a permanent deformation of the bellows from stress beyond the elastic limit of the bellows metal.

7. A steam trap according to claim 6, in which there is an included angle in the valves of not over 60 degrees, the majority of the lift of the valves, and the expansion of the bellows, being on the extension side of the bellows free length, whereby the number of convolutions of the bellows and the lift of the valves for full opening of the trap discharge are reduced.

Claims (7)

1. A thermostatic steam trap comprising a housing having a chamber therein, a partition dividing said chamber into two compartments, one compartment being provided with an inlet and the other compartment being provided with an outlet, said partition being provided with a plurality of orifices, a valve for each orifice, a single thermostatic bellows mounted in said chamber said orifices lying in a common plane and spaced transversely from the longitudinal axis of said thermostatic bellows, mechanical means extending transversely from said thermostatic bellows connecting said valves therewith so that relatively small movement of said thermostatic bellows will open said valves sufficiently to result in full flow through said orifices.

2. A thermostatic bellows steam according to claim 1, in which the mechanical connection comprises a bridge member between the bellows and the valves which is controlled by tHe expansion and contraction of the bellows.

3. A thermostatic bellows steam trap according to claim 1, in which the desired maximum opening of the trap for discharge comprises the sum of the areas of the orifices for the multiplicity of discharge valves, whereby the lift required to open each valve completely is reduced.

4. A thermostatic bellows steam trap according to claim 1, in which the mechanical connection comprises a flexible cantilever-armed beam mounted on the upper end of the bellows, operating as a bridge between the bellows and the valves, and controlled by the expansion and contraction of the bellows.

5. A thermostatic steam trap comprising a housing having a chamber therein, a partition dividing said chamber into two compartments, one of said compartments being provided with an inlet and the other compartment being provided with an outlet, said partition being provided with a plurality of orifices, a valve for each orifice a single thermostatic bellows mounted in said chamber said orifices lying in a common plane and spaced transversely from the longitudinal axis of said thermostatic bellows, (flexible) means extending transversely from said thermostatic bellows connecting said valves therewith so that relatively small movement of said thermostatic bellows will open said valves sufficiently to result in full flow through said orifices.

6. A thermostatic steam trap comprising a housing having a chamber therein, a partition dividing said chamber into two compartments, one compartment being provided with an inlet and the other compartment being provided with an outlet, a single thermostatic bellows mounted in said chamber, a multiplicity of discharge valves, a cantilever-armed beam mounted on the upper end of the bellows and operating as a bridge between the bellows and the valves to operate said valves, said bridge being flexible and thereby adapted to prevent a permanent deformation of the bellows from stress beyond the elastic limit of the bellows metal.

7. A steam trap according to claim 6, in which there is an included angle in the valves of not over 60 degrees, the majority of the lift of the valves, and the expansion of the bellows, being on the extension side of the bellows'' free length, whereby the number of convolutions of the bellows and the lift of the valves for full opening of the trap discharge are reduced.

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