US3664363A

US3664363A - Steam trap

Info

Publication number: US3664363A
Application number: US74040A
Authority: US
Inventors: Sentaro Miyawaki
Original assignee: Individual
Current assignee: Individual
Priority date: 1967-09-05
Filing date: 1970-09-21
Publication date: 1972-05-23
Anticipated expiration: 1989-05-23
Also published as: AT287740B; CH479022A; BE720447A; FR1589123A; ES358199A1; JPS5115896B1; NL6812619A; GB1220268A; SE333285B; DE1776008B1

Abstract

A disk type steam trap having a trap unit and a jacket communicating with both an inlet opening of the steam trap and a valve port passage of the trap unit having an intermediate pressure chamber, a condensate reservoir of a suitable internal volume formed below the intermediate pressure chamber, and one or more bleeder passages communicating the intermediate pressure chamber with a discharge passage. The trap unit comprises a valve seat member, a disk placed on the top of the valve seat member, and a cap forming the intermediate pressure chamber at the back of the disk. The valve seat member has an inner annular seat and an outer annular seat. The valve port passage issues from the inside of the inner annular seat and communicates with the inlet opening of the steam trap through the jacket. An annular groove is formed between the inner and outer annular seats, and the discharge passage issues from the annular groove and communicates with an outlet opening of the steam trap.

Description

PILOT VALVE This is a division of application Ser. No. 796,96l, filed Feb.

6, 1969 now US. Pat. No. 3,568,706. The present invention relates to an improved pilot valve for controlling a relief system. This invention is an improvement on the system and structure disclosed in my prior copending application Ser. No. 711,821 filed Feb. 19, 1968 now US. Pat. No. 3,512,560.

SUMMARY An object of the present invention is to provide an improved pressure relieving system in which the outlet of the main valve may be connected into a header with assurance that the main valve will not open to allow reverse flow therethrough when the header pressure exceeds the main valve inlet pressure.

Another object is to provide an improved pilot valve for a pressure relieving system whose setting may be tested with a testing fluid after it has been installed in controlling position on a relief valve without having the testing fluid flow through the pilot fluid supply line.

A further object is to provide an improved pilot valve suita ble for use on liquids and gases which includes a check valve to prevent backflow through the fluid supply line and eliminates the possibility of the inlet valve and check valve both closing and being held closed by pressure of fluid trapped therebetween.

Still another object of the present invention is to provide an improved pressure responsive device adapted to be used with a pressure relieving valve to prevent the valve from opening when the valve is subjected to higher pressures at its outlet than at its inlet.

A still further object is to provide an improved pressure relieving system which may be set for a preselected relieving pressure and also for a preselected blowdown independent of the relieving pressure setting. 7

Another object is to provide as a subcombination in an improved pressure relieving system a pressure responsive device to be used with the pressure relieving system which applies the higher of two fluid pressures to a pressure responsive member in the system.

BRIEF DESCRIPTION OF THE DRAWINGS These and other objects and advantages of the present invention are hereinafter set forth and described with reference to the structure of the present invention illustrated in the drawings wherein:

FIG. 1 is a schematic diagram of the improved relieving system of the present invention.

FIG. 2 is a detailed sectional view of the improved pilot valve of the present invention and schematically illustrating the equipment for testing the pilot valve relief setting.

FIG. 3 is an enlarged detailed sectional view of the improved pilot valve showing the inlet valve member in seated position.

FIG. 4 is a partial sectional view of the improved backflow preventer of the present invention.

FIG. 5 is a sectional view taken along line 55 in FIG. 4 showing the cross-sectional configuration of the pressure responsive member of the improved backflow preventer of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIG. 1, the improved pressure relieving system of the present invention is installed to protect tank T from over-pressure conditions. The main relief valve R is connected to have its inlet in communication with the interior of the tank -T and has its outlet 12 connected to a suitable disposal line L which may be a manifold or header of outlets from several pressure relieving systems (not shown). The main valve R includes a valve member 14 controlling the flow therethrough responsive to the pressure delivered to the pressure responsive member 16. Main valve R may be of any suitable type which includes a pressure responsive means actuating the valve member to control the flow through the main valve.

With valve R pressure on the pressure responsive member 16 is used to hold valve member 14 in closed position andwhen the pressure is vented from member 16, the pressure in inlet 10 causes valve member 14 to open.

The improved pilot valve is supplied with fluid under pressure from the tank T by the line 18 which connects from inlet 10 to the pilot valve P. Control pressure is supplied by pilot valve P through the line 20 and the back flow preventer 22 to the pressure responsive member 16 of main valve R. By controlling the pressure supplied to the pressure responsive member, 16, the pilot valve P controls the venting of tank T through the main valve R. Also, line 24 connects from outlet 12 to the backflow preventer 22 to cause the main valve R to close or remain closed whenever the pressure in the disposal line L rises to a pressure above the pressure at the inlet 10 to thereby prevent flow of fluids through the main valve R in the reverse direction. The pilot valve P is also provided with a vent port 26 through which fluid pressure in pressure responsive member 16 is vented to allow the main valve to open and relieve pressure within tank T.

The pilot valve P is shown in greater detail in FIGS. 2 and 3. Pilot valve P includes the body 28 in which a central bore 30 is formed with a plurality of ports communicating with bore 30 as hereinafter described. The shoulder 32 projecting into the bore 30 receives the valve seat assembly 34 which is held on shoulder 32 by the cage 36 and the bonnet 38. The cage 40 supports the seat insert 42 within the central bore 30 and is adjustable axially of bore 30 as hereinafter described. Communication through the central bore 30 is first through the back check seat 44 defined within the interior of cage 40, the second seat 46 defined by seat insert 42 and the outlet seat 48 defined by the seat assembly 34. The cage 40 is sealed against the walls of bore 30 and provided with ports 50 communicating from the inlet chamber 52 to the inlet seat 44 so that all flow through the pilot valve P is directed through the inlet seat 44 and the second seat 46. The inlet ports 54 and 56 both communicate with the inlet chamber 52, inlet port 54 being provided with a filter screen 58 and inlet port 56 being an alternate communication into inlet chamber 52 and normally closed by the plug 60. Control ports 62 and 64 both communicate with the intermediate chamber 66 between seats 46 and 48. Port 64 is normally closed but is provided to allow testing of the pilot valve P after it has been installed in position controlling the relief valve R as hereinafter explained. Outlet or vent port 68 communicates with outlet chamber 70. Ports 72 and 74 through cage 36 provide communication between the interior of cage 36 and outlet chamber 70. The port 76 extends through cage 36 to provide communication between the interior of bonnet 38 and the interior of cage 36.

The valve member 78 which is slidably mounted within cage 36 controls the flow through valve seat 48 responsive to the pressure forces exerted thereon and the force of the adjustable biasing means (spring 80). Spring 80 is adjustable by the threading of screw 82 through bonnet 38. Lock nut 84 is provided to retain screw 82 in its preselected position and cap 86 engages bonnet 36 and covers the outer end of screw 82 and lock nut 84. When valve member 78 is open allowing flow through valve seat 48 a portion of this flow flows through each of port 74 and port 72. The flow to port 72 is restricted by the flange 88 extending outwardly from valve member 78 and terminating in close spaced relationship to the interior of cage 36. This restricts the flow to cause the valve member 78 to snap to full open position when it first opens by exposing the entire lower side of valve member 78 to the fluid pressure from the intermediate chamber 66.

Flow from the inlet chamber 52 to the intermediate chamber 66 is controlled by valve member 90 which is slidably mounted within bore 92 of cage 40 and movable between seats 44 and 46 responsive to the pressure differential across valve member 90. Valve member 90 is preferably closely spaced with respect to the wall of bore 92 to provide a restriction to the flow of fluid through bore 92 around valve member 90. It has been found that if valve member 90 has a polygonal PATENTEDMAYNIHYZ 3.664.363

sum 5 [IF 6 PATENTEDMAY 23 I972 SHEET 6 BF 6 STEAM TRAP CROSS-REFERENCES TO RELATED APPLICATIONS This application is a continuation-in-part of co-pending application 755,942, filed on Aug. 28, 1968 now abandoned.

1. Field of the Invention This invention relates to a disk type steam trap, and more particularly to a disk type steam trap of such construction that the continuous leakage of pressure in an intermediate chamber at the back of a disk toward a discharge passage through one or more bleeder passages, is used as a factor to open a valve, which steam trap includes a condensate reservoir of a suitable internal volume at the bottom of the intermediate pressure chamber to facilitate the re-evaporation of the condensate therein and a jacket for heating both the condensate reservoir and the intermediate pressure chamber, whereby the interval between a closing of the valve and the succeeding opening of the valve is controlled by the leakage of the pressure of the thus reevaporated steam.

2. Description of the Prior Art A typical known disk type steam trap is disclosed by U.S. Pat. No. 2,817,353, which has been regarded as an epochmaking step in the art of compact steam traps. The known disk type steam trap includes a valve seat member with an inlet passage, and concentric double annular seats, i.e. an inner and an outer annular seats, formed on the upper surface of the valve seat member. The inlet passage is communicated with a port at the center of the inner annular seat at one end thereof, and with an inlet opening of the steam trap for receiving steam and condensate at the opposite end thereof. An annular groove is defined between the inner and the outer annular seats, and the annular groove is communicated with a discharge passage. A disk is placed on the annular seats, so that the lower surface of the disk comes into operative engagement with both the inner and the outer annular seats. In other words, the disk and the annular seats constitute a valve. A cap is mounted on the valve seat member so as to form an intermediate pressure chamber above the disk between the upper surface of the disk and the inner surface of the cap. When a steam system including such steam trap is started up, a large amount of low temperature condensate mixed with air acts to push the disk upwards away from the seats and proceeds into the discharge passage through the annular groove between the inner and the outer annular seats. As the condensate discharge proceeds, the temperature of the condensate at the steam trap increases gradually, and at the same time, the flow rate of the condensate on the lower surface of the disk increases. Accordingly, the pressure at the lower surface of the disk is reduced. On the other hand, toward the end of the discharging process of the initial condensate at the start-up, high temperature condensate fills up the intermediate pressure chamber through a clearance between the periphery of the disk and the inner peripheral surface of the cap. The high temperature condensate in the intermediate pressure chamber re-evaporates and the pressure of the thus re-evaporated steam forces the disk downward to the annular seats to close the valve, or to interrupt the communication between the inlet passage and the discharge passage.

The heat of the high temperature condensate in the intermediate pressure chamber dissipates to the outside through the cap, and accordingly, the temperature of the condensate and the pressure of the re-evaporated steam also decrease. When the pressure of the re-evaporated steam is so reduced as to be surpassed by the pressure of the steam system, the disk is pushed upwards to open the valve to allow the release or discharge of the of the condensate to the discharge passage. Thus, in this known disk type steam trap, the duration of the valve closure with the disk kept in contact with the annular seats depends on the ambient temperature, such as room temperature.

If the intermediate pressure chamber of the aforesaid known steam trap should somehow be filled up with low temperature condensate for some period of time, the pressure in the intermediate pressure chamber does not decrease any more, and as a result of it, the disk urged to the annular seats cannot move upwards to open the valve. Thus, the function of the steam trap cannot be fulfilled. Such conditions are generally referred to as a locking phenomenon."

Such locking phenomenon can be avoided by forming a bleeder passage on the lower surface of the disk so as to communicate the intermediate pressure chamber with the discharge passage therethrough, as disclosed by British Pat. No. 575,490. With such bleeder passage, the pressure of the steam re-evaporated form the condensate in the intermediate pressure chamber continuously leaks to the discharge passage, so that the pressure within the intermediate pressure chamber decreases gradually. Thereby, the pressure of the steam system surpasses the pressure within the intermediate pressure chamber after a certain period of time and forces the disk upwards to open a valve. The disk type steam trap with such bleeder passage has a disadvantage in that the pressure within the intermediate pressure chamber tends to decrease too fast, at least in comparison with that of the preceding steam trap, according to U.S. Pat. No. 2,817,353, and such too fast reduction of the pressure in the intermediate pressure chamber results in excessively frequent operation of the disk to accelerate the wearing thereof. Furthermore, if such steam trap with bleeder passage is applied to a steam system producing only very little condensate, the frequent operation of the disk causes excessive and wasteful discharge of the useful hot condensate and steam.

In order to obviate such difficulties, U.S. Pat. No. 2,945,505 proposed to surround the intermediate pressure chamber with the steam and condensate, instead of directly exposing it to the atmosphere, so that the operating frequency of the disk may not be affected by the difference of the ambient temperature. Accordingly, the duration of the interval between succeeding condensate discharging operations become longer, resulting in the improved durability of various components of the steam trap and elimination of the loss of useful steam and hot condensate due to unnecessarily frequent operations of the disk. However, with the construction of U.S. Pat. No. 2,945,505, the intermediate pressure chamber is continuously surrounded by steam and hot condensate from the steam system, and hence, the chance of decrease in the pressure within the intermediate pressure chamber tends to be suppressed excessively, resulting in too long intervals between succeeding valve opening operations. As a result of it, the condensate in the steam system may not be discharged successfully. In other words, there is a serious danger that condensate is accumulated on the inlet side of the steam trap or within various devices in the steam system, which hampers the smooth operation of the steam system. The steam trap of U.S. Pat. No. 2,945,505 is also liable to the aforesaid locking phenomenon, as in the case of the structure according to U.S. Pat. No. 2,817,353.

The applicant proposed, in his Japanese Pat. No. 314,527, a solution of the difficulties of the aforesaid U.S. and British Patents. More particularly, the applicant disclosed the use of a jacket communicating with the inlet of a steam trap and surrounding an intermediate pressure chamber, in conjunction with a disk having bleeder passages communicating the intermediate pressure chamber with a condensate discharge passage, so as to avoid the direct exposure of the intermediate pressure chamber to the atmosphere to eliminate the dependence of the operating frequency of the disk on the ambient temperature, which disk is interchangeable with a similar disk having bleeder passages of different size, for the sake of attaining the best fluid flow rate from the intermediate pressure chamber to the discharge passage for different conditions of various steam systems. With the steam trap having such jacket and the interchangeable disk, the operating frequency is not affected by the ambient temperature, and in addition, the danger of the locking phenomenon is completely eliminated. In other words, the operating frequency of the steam trap or the rate of pressure decrease in the intermediate pressure chamber, is very little affected by the ambient temperature, and it is determined by the temperature of the fluid in the jacket surrounding the intermediate pressure chamber and the fluid flow rate from the intermediate pressure chamber to the discharge passage through the bleeder passage formed on the disk. Thus, the operation of the disk and the timing of the valve opening operation can be so controlled as to best suit the conditions of each steam system, and at the same time, the danger of the locking phenomenon is completely eliminated.

The control of the pressure in the intermediate pressure chamber of the steam trap according to Japanese Pat. No. 314,527, which is basic to the present invention, will be described in further detail. The condensate in the intermediate pressure chamber is re-evaporated by heating with the steam or hot condensate within the jacket surrounding the intermediate pressure chamber, and at the same time, the steam thus re-evaporated leaks to the discharge passage through the bleeder passage formed on the disk. Thus, the pressure in the intermediate pressure chamber is reduced, to allow the upward movement of the disk for opening the valve. It is necessary to control the timing of the valve opening or the upward movement of the disk, so that the amount of condensate at the inlet of the steam trap can be maintained below a level harmful for various steam devices in the steam system. In the case that the amount of condensate generated in the steam system is small, the operating frequency of the disk should be so controlled as to match the quantity of the condensate. In other words, when the amount of condensate is large, the interval between succeeding valve opening operations should be short, on the other hand, when the quantity of the condensate is small, the interval between the succeeding valve opening operations should be long. In the disk type steam trap of Japanese Pat. No. 314,527, the inner volume of the intermediate pressure chamber is limited, and accordingly, the amount of condensate to be stored therein is also limited. Consequently, the condensate in the intermediate pressure chamber is used up within a very short period of time by the leakage through the bleeder passages. Therefore, the aforesaid disk type steam trap of Japanese Pat. No. 314,521 is not very effective in the case of steam system having an extremely small quantity of condensate generated therein, because the steam trap tends to open the valve too early for such steam system.

As described in the foregoing, there are four major variations in the structure of disk type steam trap.

l. A steam trap with an intermediate pressure chamber whose outer periphery is directly disposed to the outside, for instance U.S. Pat. No. 2,817,353. This is the fundamental structure of disk type steam trap.

2. A steam trap whose intermediate pressure chamber is surrounded and heated by the inlet side steam or condensate, so that the operating frequency of the steam trap may not be directly afiected by the ambient temperature, for instance U.S. Pat. No. 2,945,505.

3. A steam trap having an intermediate pressure chamber, whose outer periphery is directly disposed to the outside atmosphere, and a disk with bleeder passages for allowing leakage of the pressure in the intermediate pressure chamber to the outlet side, for instance British Pat. No. 575,490.

4. A steam trap having a jacket for heating the intermediate pressure chamber, in a manner similar to that of the aforesaid steam trap of item 2, and a disk with bleeder passages, of which operating frequency is adjustable, for instance Japanese Pat. No. 314,527.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to obviate the difiiculties of the disk type steam traps of the aforesaid prior art by providing a novel steam trap having an intermediate pressure chamber, an annular condensate reservoir formed at the lower end of the intermediate pressure chamber, for holding a large amount of condensate therein each time the condensate is discharged through the steam trap, a jacket communicated with the inlet of the steam trap and surrounding said intermediate pressure chamber, so as to continuously surround and heat the intermediate pressure chamber with the inlet side steam and hot condensate for effecting reevaporation of the condensate in both the condensate reservoir and the intermediate pressure chamber to maintain the valve closing force and to lengthen the valve closing period, and a disk with one or more bleeder passages for controlling the pressure in the intermediate pressure chamber by allowing the continuous leakage of the pressure in the intermediate pressure chamber to the discharge side, whereby the optimum operating frequency of the steam trap can be achieved under any conditions. The feature of the present invention is in that the condensate reservoir of a suitable inner volume is formed at the lower end of the intermediate pressure chamber, so as to insure that a certain amount of condensate is held in the condensate reservoir as the source of the reevaporated steam in the intermediate pressure chamber.

For a better understanding of the invention, reference is made to the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are sectional views, illustrating different known disk type steam traps;

FIG. 3 is a vertical sectional view of a disk type steam trap embodying the present invention;

FIGS. 4a to 40 are a vertical sectional view of another disk type steam trap according to the present invention, having fillers selectively fitted in the condensate reservoir, and a plan view and a sectional view of the filler, respectively;

FIG. 5 is a vertical sectional view of another disk type steam trap according to the present invention having a plate-like strainer disposed at the top of a flow guide cylinder;

FIGS. 6a to 6d are diagrammatic illustrations of a steel inner cap, usable in the steam trap according to the present invention', and

FIG. 7 is a sectional view of another steam trap according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Like parts are designated by like numerals and symbols throughout the drawings.

FIG. 1 shows the essential structure of a known type steam trap, disclosed by U.S. Pat. No. 2,817,353, in a vertical sectional view. A base body 1 has an inlet 2 and an outlet 3. An inner annular seat r1 and an outer annular seat r2 are formed at the top of the base body 1, and a disk 8 is placed on the annular seats r1 and an outer annular seat r2. A cap 10 is mounted on a valve seat member 9 of the base body I, so as to define an intermediate pressure chamber 21 above the disk 8. An inlet passage or a valve port passage 17 is formed through the base body 1 in such fashion that one end of the valve port passage 17 communicates with the center of the inner annular seat r1, while the opposite end of the valve port passage 17 communicates with the inlet 2. An annular groove 18 formed between the inner and the outer annular seats communicates with one end of a discharge passage 19. The other end of the discharge passage 19 communicates with the outlet 3. Thus, the inner annular seat rl is disposed at the boundary between the valve port passage 17 and the discharge passage 19, so that the valve port passage 17 is communicated with and interrupted from the discharge passage 19 depending on whether the disk 8 engages the inner annular seat r1 or not. An annular clearance 23 is provided between the outer periphery of the disk 8 and the inner cylindrical surface of the cap 10. As described in the foregoing, the steam trap of this structure has a disadvantage in that the locking phenomenon may take place if the intermediate pressure chamber 21 is filled with low temperature condensate while the disk 8 engages the annular seats r1 and r2.

FIG. 2 shows a vertical sectional view of a steam trap disclosed by Japanese Pat. No. 314,270. A cover 14 is mounted on a base body 1, so as to cover a cap and to define a jacket 16 between the cap 10 and the cover 14. One or more bleeder passages S1 are formed between an outer annular seat r2 and a disk 8. The steam trap of this structure has an undesirable tendency that the condensate held in an intermediate pressure chamber 23 is used up in a very short period of time. Accordingly, the steam trap of FIG. 2 is not applicable to some steam systems having only a very limited amount of condensate produced therein.

FIG. 7 is a vertical sectional view, showing the essential structure of a steam trap according to the present invention. A base body 1 has an inlet 2 and an outlet 3. The inlet 2 communicates with a charging passage 6 through a strainer chamber 5 having a strainer 4 disposed therein. The outlet 3 communicates with a mounting hole 7 of the base body 1. A trap unit 11, which consists of a valve seat member 9, a cap 10 secured to the valve seat member, and a disk 8 fitted therebetween, is mounted on the base body by screwing the threaded lower end portion of the valve seat member 9 to the tapped mounting hole 7.

A cover 14, enclosing the trap unit 11, is fastened to the base body 1 by bolts 15. The space between the cover 14 and the trap unit 11 defines a jacket 16, which communicates with the inlet 2 through the charging passage 6 to receive steam and hot condensate therefrom. The steam and hot condensate thus received surround and heat the trap unit 11.

In the trap unit 11, an inner annular seat r1 and outer annular seat r2 are formed at the top of the valve seat member 9 in a concentric fashion, and the disk 8 selectively engages the annular valve seats, so that the lower surface of the disk 8 comes into direct and tight contact with the upper surface of the annular seats. A valve port passage 17 formed within the valve seat member 9 communicates with a valve port located inside the inner annular seat r1 at one end thereof and with the jacket 16 at the opposite end thereof, as depicted in FIG. 7. An annular groove 18 is formed between the inner and the outer annular seats r1, r2, and a discharge passage 19 issues from the annular groove 18 and extends to the mounting hole 7 of the base body 1, so as to communicate with the outlet opening 3 of the steam trap. In other words, a valve is formed by the annular seats r1, r2 and the disk 8, which opens and closes depending on whether the disk 8 engages the annular seats r1, r2, so as to complete and interrupt the communication between the valve port passage 17 and the discharge passage 19, respectively.

In this particular embodiment of the present invention, very fine grooves or bleeder passages S1 and S2 of different widths and depths are formed on the upper and lower surfaces of the disk 8, respectively, in the radial direction emanating from the center of the disk surface. ln the figure, the bleeder passage S1 acts to provide a limited communication from an intermediate pressure chamber 21, formed between the disk 8 and the cap 10, to the discharge passage 19 through the annular groove 18. Thereby, the pressure within the intermediate pressure chamber 21 is allowed to continuously leak to the outside of the steam trap through the discharge passage 19 and the outlet 3. The inner surface of the top portion of the cap 10 acts as a stopper 20 to limit the movement of the disk 8, and as described above, the intermediate pressure chamber 21 is formed between the upper surface of the disk 8 and the inner surface of the cap 10. The lower end of the intermediate pressure chamber is enlarged so as to form an annular condensate reservoir 22 of a certain internal volume.

Fine clearance 23 is provided between the outer periphery of the disk 8 and the inner cylindrical surface of the cap 10, and the intermediate pressure chamber 21 and the condensate reservoir 22 are communicated with each other through the clearance 23.

In the disk type steam trap of the aforesaid construction, according to the present invention, when a steam system including the steam trap is started up, the condensate of the steam system reaches the inlet 2 and flows into the jacket 16 through the strainer 4 and the charging passage 6. Thereafter, the condensate enters the valve port passage 17 and pushes up the disk 8. A part of the condensate fills up the intermediate pressure chamber 21 and the condensate reservoir 22, while the remaining portion, or the major portion, of the condensate rushes into the discharge passage 19 through the annular groove 18 between the inner and the outer annular seats r1, r2, and flows out of the steam trap through the outlet 3 integrally formed on the base body 1.

The design of the trap unit 11 is such that the pressure at the lower surface of the disk 8 is kept higher than at the upper surface thereof, as long as the low temperature condensate flows out of the steam trap. Toward the end of a condensate discharging operation, the temperature of the condensate discharging operation, the temperature of the condensate becomes higher, and accordingly the re-evaporation of the condensate is activated at various portions of the steam trap. Especially, the fluid acting on the disk 8 from the valve port passage 17, so as to push up the disk, becomes a mixture of steam and condensate rather than liquid phase condensate alone. The percentage of steam in the fluid through the valve port passage 17 increases as the condensate discharging operation approaches to its end. In other words, the specific volume of the fluid being discharged becomes larger toward the end of the condensate discharging operation. Generally speaking, if a fluid flows through a certain passage with a certain pressure difference across the passage, it is apparent that the velocity of the fluid therethrough becomes higher as the specific volume of the fluid increases. According to the Bernoullis theorem, the static pressure of the fluid becomes smaller as its velocity increases. Thus, the pressure at the lower surface of the disk 8 becomes smaller as the condensate discharging operation approaches to its end. In addition, due to the temperature rise and other reasons, the pressure within the intermediate pressure chamber increases at the end of the condensate discharging operation. Consequently, the disk 8 is forced downwards and comes into contact with the annular seats r1 and r2, to close the valve and interrupt the communication between the valve port passage 17 and the discharge passage 19.

It should be noted here that hot condensate available at the end of the condensate discharging operation is stored in the intermediate pressure chamber 21 as well as in the condensate reservoir 22, when the condensate discharging operation ceases, so that the pressure in the intermediate pressure chamber 21 is smoothly controlled by the balance between the reevaporation of the hot condensate by heating with the steam or hot condensate in the jacket 16 and the leakage of the pressure through the bleeder passage S1. Thus, the proper duration of the valve closing period, or the interval between the succeeding condensate discharging operations, can be insured at a certain preselected value.

It is essential in the present invention that the internal volume of the condensate reservoir 22 should be large enough to store a sufficient amount of condensate for making up for the pressure leakage through the bleeder passage S1 by the reevaporation of the thus stored condensate for the desired duration of the aforesaid valve closing period.

An important feature of the steam trap of the present invention is in that a proper duration of the valve closing period, or the interval between succeeding condensate discharging operations, can be selected at will by controlling the rate of the pressure leakage from the intermediate pressure chamber through the bleeder passage, so as to match with any operative conditions required for the steam trap. For instance, in FIG. 7, if the disk 8 is turned over to bring the bleeder passage S2, which is different from the passage S1 in size, into contact with the outer annular seat r2, then the rate of pressure leakage therethrough is modified. Therefore, the danger of harmful accumulation of a large amount of condensate at the inlet 2 and on the inlet side of the steam trap can be completely avoided, together with the danger of too fast valve opening operation causing wasteful discharge of steam and hot condensate.

Furthermore, it is an important feature of the steam trap of the present invention that the possibility of the aforesaid locking phenomenon at the time of start-up is completely eliminated by the use of the bleeder passage S1 or S2.

Consequently, the dimensions of the valve port passage 17, the discharge passage 19, the disk 8, and the annular groove 18 can be comparatively freely selected in a wide range. In the case of conventional disk type steam traps, the dimensions of the aforesaid parts have heretofore been limited to a very narrow range and there has not been any room left for free choice. As a result of it, the range of the operative characteristics of the disk type steam trap has been expanded and a wide variety of performance characteristics of the steam trap have become available.

More particularly, with conventional disk type steam traps, the dimensions and sectional areas of the valve port passage 17, the discharge passage 19, the disk 8, and the annulargroove 18 have been determined by experiments, and the deviation of the dimensions from the experimentally determined values has been the possible cause of sustained blow-E of steam and the aforesaid locking phenomenon at the time of start-up, as well as numerous other operational troubles. In other words, with conventional disk type steam traps, satisfactory stable operation thereof cannot be expected unless the experimentally determined dimensions of various parts are strictly adopted. On the other hand, in the disk type steam trap according to the present invention, the availability of the valve closing pressure in the intermediate pressure chamber is continuously maintained by providing a condensate reservoir, acting as a resource for the re-evaporated steam, so as to counterbalance the leakage of the pressure through the bleeder passage. With the use of the condensate reservoir according to the present invention, it is made possible by proper modification of the aforesaid dimensions to open the valve or to start the condensate discharging operation when the temperature of the condensate is at a desired value, such as the saturation temperature or a temperature considerably below the saturation temperature. In other words, according to the present invention, as long as the dimensions of various parts satisfy the conditions for closing the valve, or for forcing the disk 8 downwards, the generation of the force for opening the valve, or for forcing the disk upwards, is guaranteed by the use of the bleeder passage.

The inventor found that the introduction of the selectivity of a variety of performance characteristics of the disk type steam traps, which is made available by the present invention, is a significant contribution to the art.

In the known steam trap of FIG. 2, the disk valve 8 is prone to chattering. The condensate delivered to the intermediate chamber 21 at the moment of the closure of the disk valve 8 is heated by the inlet steam in the jacket 16, so as to evaporate the condensate in the intermediate chamber 21 for maintaining a comparitively high steam pressure therein for keeping the disk valve 8 closed. On the other hand, the disk valve 8 is provided with bleeder passages S1 for allowing the leakage of the steam pressure from the intermediate chamber 21 to the outlet 19. As a result, the pressure in the intermediate chamber 21 may be reduced below the inlet steam pressure after a certain time interval, for allowing the upward movement or the opening of the disk valve 8. With the construction of FIG. 2, it is extremely difficult to provide a sufficiently long time interval from the closure of the disk valve 8 to the succeeding opening thereof. Accordingly, the valve disk 8 is subjected to frequent chattering.

Theoretically, such chattering may be avoided by reducing the cross sectional size of the bleeder passages. However, in practice, it is impossible to make bleeder passages smaller than several microns in width and depth. In the present invention, a series of test was conducted on such small passages. When the inlet pressure is about 15 psi or higher, the disk valve stays as closed only for a few seconds and continuous chattering of the disk valve was noticed. Consequently, the seating surface of the disk valve was worn out so quickly that the service life of the steam trap of such construction was rather short and the steam trap proved to be rather impractical. On the other hand, when the pressure was low, e.g., less than about 15 psi, water membranes were formed on the bleeder passages, due to the surface tension of the condensate, and the bleeder passage is blocked and disabled. Thus, the steam trap with such extremely small bleeder passages is also impractical for such low pressure applications. In other words, the bleeder passages must be larger than a certain minimum size, so as to ensure proper function thereof.

The present invention successfully solves such difiiculties by using the condensate reservoir 22, having a volume available for temporary storage of condensate that is large enough for generating a sufficient amount of steam for keeping the disk valve open for a reasonable period of time without causing any chattering. In a preferred embodiment of the present invention, the minimum size of the bleeder passage S1 is about 0.2 mm (about 200 microns) in width and about 0.3 mm (about 300 microns in depth. However, with applicants Japanese Pat. No. 314,527, bleeder passages are too small, and the condensate in the intermediate pressure chamber is exhausted too quickly due to the lack of the condensate reservoir, so that the disk valve 8 is prone to chattering.

Thus, the condensate reservoir of the present invention is clearly different from the annular space radially outward of I the outer annular seat r2 of FIG. 2 in construction, purpose, and function.

Furthermore, as determined in the present invention, in order to ensure proper intervals between successive closures of the disk 8, the free space formed in the condensate reservoir 22 below the contact surface between the disk 8 and the annular seats r1, r2 must not be smaller than the free space formed in the intermediate chamber 21 above the last mentioned contact surface. The free space of the condensate reservoir 22 in the embodiment of FIG. 7 is equivalent to the volume of the annular cavity between the outer surface of the seat r2 and the inner surface of the enlarged portion of the narrow gap between the intermediate pressure chamber 21 and the condensate reservoir 22 which is below the aforesaid contact surface. Such free space of the condensate reservoir 22 is available for the temporary storage of the condensate. The free space of the intermediate pressure chamber 21 is given as a difference between the inside volume of the top portion of the cap 10 above the aforesaid contact surface and the solid volume of the disk 8.

In the embodiment of FIG. 7, the condensate reservoir 22 is made by enlarging a part of the cap 10, but it is also possible to form it by contracting the valve seat member 9. The shape of the condensate reservoir 22 is not restricted to an annular form, as depicted in the figure. For instance, one or more suitable cavities may be formed on the outer peripheral surface ofthe valve seat member 9 or the cap 10, so as to communicate with the narrow gap between the seat member and the cap 10, while providing space for temporary storage of the condensate.

FIG. 3 illustrates another embodiment of the invention. The embodiment of FIG. 3 is substantially the same as that of FIG. 7, except that a flow guide cylinder 12 is mounted on a base body 1, so as to surround a trap unit 11, and overflow holes 13 are bored at the upper edge of the cylinder 12. In operation of the steam trap of FIG. 3, the condensate from the strainer 4 enters into the outside of the flow guide cylinder 12, and then overflows through the overflow holes 13 at the upper edge of the flow guide cylinder 12 and proceeds along the flow guide cylinder 12, so as to heat the trap unit 11.

In the embodiments of FIGS. 3 and 7, the bleeder passage S1 or S2 is fabricated in the form of a fine groove radially bored on the surface of the disk 8, so that the bleeder passage extends across the upper surface of the outer annular seat r2 when the disk 8 engages the annular seats. However, the form of the bleeder passage is not limited to such fine groove on the disk 8, but many other different forms can be used. For instance, the bleeder passage can take the form of a small hole or an orifice bored through the disk 8 so as to communicate the intermediate pressure chamber 21 with the annular groove 18, or fine grooves bored on the upper surface of the outer annular seat r2, or a small hole or an orifice bored through the wall of the outer annular seat r2 so as to communicate the intermediate pressure chamber 21 with the annular groove 18. If a small hole or an orifice through the disk 8 is used, it is possible to taper or vary the diameter of the hole or the orifice from one side to the opposite side of the disk, so that the resistance against fluid flow therethrough in one direction is different from that in the opposite direction. Thereby, the conditions for pressure leakage from the intermediate pressure chamber 21 to the discharge passage 19 can be changed simply by turning over the disk 8, so as to meet different requirements of the steam system on the steam trap.

Besides, the number of the bleeder passage is not limited to one, but any number of bleeder passages can be used to achieve the optimum performance characteristics of the steam trap.

Moreover, the structures of FIGS. 3 and 7 have an advantage in that the replacement of the trap unit 11 can be carried out simply by removing the cover 14 and turning around the trap unit to remove the trap unit from the mounting hole 7, followed by mounting a new trap unit on the mounting hole 7 and re-mounting the cover 14 on the casing 1. Thus, the wearing of the various parts of the trap unit can be very easily dealt with by replacing the old trap unit with a new one.

FIG. 4a shows a disk type steam trap similar to that of FIG. 3, except that fillers are placed in the condensate reservoir 22. Some steam systems, such as a syphon drainage system, require rather frequent condensate discharging operations with short valve closing periods. For such systems, a suitable number of fillers 24, e.g. two ring fillers as depicted in FIGS. 4b and 4c, can be placed in the condensate reservoir 22 in order to reduce the effective internal volume of the reservoir 22. It is apparent to those skilled in the art that the interval between succeeding discharging operations can be shortened by reducing the amount of the condensate stored in the condensate reservoir 22, which reduction can be effected by decreasing the effective internal volume of the condensate reservoir 22 by placing fillers therein. It should be noted here that the intervals between the successive condensate discharging operations can be controlled more accurately by selecting proper dimensions of the bleeder passages, such as S1 and S2, in conjunction with the application of the ring fillers.

FIG. 5 shows a modification of the steam trap of FIG. 3 by replacing the cylindrical strainer 4 of FIG. 3 with a disk-shape strainer disposed at the top of a flow guide cylinder. In FIG. 5, a disk-shape strainer 25 is disposed at the top of a flow guide cylinder 12, so that hot condensate can be distributed uniformly over a cap defining the outer periphery of an intermediate pressure chamber 21. Thus, the heating effects of the fluid within the intermediate pressure chamber 21 can be improved. A spring 26 is secured to the upper side of the diskshape strainer 25, so that the operative engagement among the cylinder 12, the strainer 25, and a base body 1 can be completed in one step at the time of mounting the cover 14 on the base body 1.

FIG. 6a is a vertical sectional view of a cap 10 defining an intermediate pressure chamber 21. According to conventional designs, the entire cap 10 is made of stainless steel having a comparatively high hardness, while forming a valve seat member 9 with the similar stainless steel, in order to minimize the wearing of the inner surface of the cap 10 by a disk 8 reciprocating vertically within the intermediate pressure chamber 21 defined by the inner surface of the cap 10 and the disk 8. As described above, in a preferred embodiment of the present invention, the cap 10 is mounted on the valve seat member 9 by screwing to form a trap unit, and when the trap unit 11 is exposed to steam and hot condensate for an extended period of time, the tapped portion of the cap 10 tends to be seized to the threaded portion of the valve seat member 9. Thus, sometimes the cap 10 becomes inseparable from the valve seat member 9, due to such seizure. In order to avoid such seizure, the cap 10 of FIG. 6a is made of metallic material which is hardly seizable to stainless steel, e.g. copper alloys. To prevent wearing of the inner surface of the cap 10 made of a copper alloy, an inner cap 27 (FIGS. 6b and 6c) made of stainless steel is fitted on the inside surface thereof, and a snap ring 28 (FIG. 6d) is so fitted in an annular groove formed on the inner surface of the cap 10 at the lower end of the inner cap 27 so as to hold the inner cap 27 in position. It has been proved that the interchangeability of the cap 10 is greatly improved by the use of the construction including a copper alloy cap and a stainless steel inner cap fitted therein, as depicted in FIGS. 6a to 6d. Referring to FIG. 60 the outer diameter of a stopper 20 is selected to be slightly smaller than the outer diameter of the annular groove 18 (FIG. 5) cooperating with a disk 8 (FIG. 5) to be stopped by the stopper 20, while the inner diameter of the stopper 20 is larger than the inner diameter of the annular groove 18. In other words, the width of the stopper 20 in the radial direction is smaller than the corresponding width of the annular groove 18. Thereby when the disk 8 is turned over for some reasons, scratches made on one side surface of the disk 8 by the stopping action of the stopper 20 do not engage with the upper surface of annular seats r1 and r2 (FIG. 5), so as to insure the steam tight contact between the seats and the disk.

The construction of the cap 10 of FIGS. 6a to 6d has another advantage in that when the inner cap 27 is worn out, it can be easily replaced with a new inner cap 27, so as to insure accurate operation of the steam trap for a long period of service time.

The conditions for closing the valve, or for forcing the disk downwards, have been described in detail in the foregoing. As regards the conditions for opening the valve, or for pushing the disk upwards, there are the following three factors affecting the closing of the valve.

a. The natural heat dissipation from the outer surface of the jacket 16, formed between the cover 14 and the trap unit 11, which cools down the condensate in the jacket 16, and accordingly, reduces the temperature in the intermediate pressure chamber 21 of the trap unit 11. The leakage of the pressure in the intermediate pressure chamber 21 through one or more bleeder passages, e.g. S1 or S2. The intervals between succeeding condensate discharging operations can be controlled by properly selecting the number and the size (e.g. width and depth) of such bleeder passages.

c. The exhaustion of the condensate in the annular condensate reservoir 22. The exhaustion of the condensate interrupts the supply of the re-evaporated steam to the intermediate pressure chamber 21, and thereby, forces the opening of the valve, or the upward movement of the disk 8. It is also possible to control the intervals between the succeeding condensate discharging operations by changing the amount of the condensate storable in the condensate reservoir 22.

Among the aforesaid three factors, the factor (a) affects the longest interval between the discharging operations, while the combination of the factors (b) and (c) enables the choice of any desired intervals between the succeeding discharging operations.

I claim:

1. A disk type steam trap comprising:

a base body having an inlet opening and an outlet opening, a trap unit consisting of a valve seat member secured to the base body and having an inner and an outer annular seat formed on the top surface of the member, a valve port passage bored through the seat member and communicating with the inside of said inner annular seat at one end thereof and with said inlet opening at the opposite end thereof, an annular groove formed between said inner and outer annular seats, and a discharge passage bored through the valve seat member and communicating with said outlet opening at one end thereof and with said annular groove at the opposite end thereof, a disk operatively engageable with said inner and outer seats for acting as a valve between the valve port passage and the annular groove, a cap secured to the valve seat member so as to enclose the disk with a suitable spacing therefrom, an intermediate pressure chamber formed within the inside of the cap above the contact surface between the annular seats and the disk, the pressure in the intermediate pressure chamber acting on the top surface of the valve for causing the disk to come in contact with the annular seats and move away from the annular seats depending on the balance of the pressure in the intermediate pressure chamber and the inlet pressure at the valve port passage, at least one bleeder passage communicating said intermediate pressure chamber with said discharge passage, and a condensate reservoir formed within the inside of said cap below said contact surface and communicating with said intermediate pressure chamber, the volume of the condensate reservoir below said contact surface of the disk being not smaller than the volume of the intermediate pressure chamber above said contact surface, and a cover secured to the base body so as to enclose the trap unit with a spacing therefrom, the spacing between the cover and the trap unit forming a jacket which surrounds the trap unit and providing an intermediate passage between the inlet opening of the base body and the valve port passage.

2. A disk type steam trap according to claim I, wherein the condensate reservoir consists of an enlarged portion of the cap.

3. A disk type steam trap according to claim 1, wherein the condensate reservoir consists of contracted portions of the valve seat member surrounded by the cap.

4. A disk type steam trap according to claim 1, wherein the condensate reservoir consists of a plurality of cavities formed between the cap and the valve seat member below the top surface of the annular seats engageable with the disk.

5. A disk type steam trap according to claim 1, wherein the condensate reservoir is an annular cavity defined between the inner stu'face of the cap and the outer surface of the valve seat member.

6. A disk type steam trap according to claim 1 and further comprising a flow guide cylinder having overflow holes formed at the upper edge thereof and disposed in said jacket so as to surround said trap unit wherein the outside of said flow guide cylinder communicates with said inlet while communicating the inside of said flow guide cylinder with said valve port passage, whereby the fluid from said inlet overflows through said overflow holes and enters into said valve port passage.

7. A disk type steam trap according to claim 1 and further comprising at least one filler replaceably fitted in said condensate reservoir, so as to modify the internal volume of said condensate reservoir.

8. A disk type steam trap according to claim 6 and further comprising a disk-shape strainer so disposed as to cover the top of said flow guide cylinder.

9. A disk type steam trap according to claim 1, wherein said cap is made of a metallic material hardly seizable to said valve seat member and has an inner cap made of anti-abrasive material and fitted on the inside of said cap so as to cover the inside surface of the top and the cylindrical side wall thereof.

10. A disk type steam trap according to claim 9, wherein said cap is made of brass and said inner cap is made of steel.

Claims

1. A disk type steam trap comprising: a base body having an inlet opening and an outlet opening, a trap unit consisting of a valve seat member secured to the base body and having an inner and an outer annular seat formed on the top surface of the member, a valve port passage bored through the seat member and communicating with the inside of said inner annular seat at one end thereof and with said inlet opening at the opposite end thereof, an annular groove formed between said inner and outer annular seats, and a discharge passage bored through the valve seat member and communicating with sAid outlet opening at one end thereof and with said annular groove at the opposite end thereof, a disk operatively engageable with said inner and outer seats for acting as a valve between the valve port passage and the annular groove, a cap secured to the valve seat member so as to enclose the disk with a suitable spacing therefrom, an intermediate pressure chamber formed within the inside of the cap above the contact surface between the annular seats and the disk, the pressure in the intermediate pressure chamber acting on the top surface of the valve for causing the disk to come in contact with the annular seats and move away from the annular seats depending on the balance of the pressure in the intermediate pressure chamber and the inlet pressure at the valve port passage, at least one bleeder passage communicating said intermediate pressure chamber with said discharge passage, and a condensate reservoir formed within the inside of said cap below said contact surface and communicating with said intermediate pressure chamber, the volume of the condensate reservoir below said contact surface of the disk being not smaller than the volume of the intermediate pressure chamber above said contact surface, and a cover secured to the base body so as to enclose the trap unit with a spacing therefrom, the spacing between the cover and the trap unit forming a jacket which surrounds the trap unit and providing an intermediate passage between the inlet opening of the base body and the valve port passage.

2. A disk type steam trap according to claim 1, wherein the condensate reservoir consists of an enlarged portion of the cap.

5. A disk type steam trap according to claim 1, wherein the condensate reservoir is an annular cavity defined between the inner surface of the cap and the outer surface of the valve seat member.