GB2159921A

GB2159921A - Fluid control valve

Info

Publication number: GB2159921A
Application number: GB08413602A
Authority: GB
Inventors: Gary Stephen Mumford; Rowland Charles Smith
Original assignee: DeVilbiss Co Ltd; DeVilbiss Co
Current assignee: DeVilbiss Co Ltd; DeVilbiss Co
Priority date: 1984-05-29
Filing date: 1984-05-29
Publication date: 1985-12-11
Also published as: GB2159921B; GB8413602D0

Abstract

A valve has a barrel (10) rotating in a body connected to a fluid delivery line (12), a fluid return line (14) and a solvent line (16). The valve controls fluid flow to a hose delivery line (18) and return line (20) leading to hose (27). The barrel (10) is formed with bores (25-26, 28, 29-32) defining three sets of flow paths and the body is formed with fluid flow loops (25-27). In a first position of barrel (10) the fluid supply and return lines (12, 14) are connected to the hose (27) through the angular passages (28, 29). In a second position (Fig. 2) the hose (27) is isolated and fluid from line (12) recirculates through passages (31, 32) to line (14). In a third position (Fig. 3) the solvent line (16) is series connected to the hose through all the passages to the hose (27) for flushing purposes. <IMAGE>

Description

SPECIFICATION Fluid control valve This invention relates to a valve for controlling a recirculating flow of liquid from a supply to a recirculating fluid hose.

Some materials, especially those containing particulate matter such as paints, need to be kept in circulation to maintain the suspension of the particles in the fluid. In many large painting installations for example, paints and finishing materials are pumped from a central mixing and storage area via pipe lines to the point of use and back to the mixing area thus being kept in continual circulation. Such importance is attached to this that standby pumps on loop lines are available so that in the event of failure or maintenance requirement of the pump in use, the standby can be switched in to the system with minimal delay. Also, the systems are continuously operated through weekends, holidays and other closure periods in order to prevent settlement of particulate matter and consequent blockage of the main feed lines.

For several years, recirculation features have been provided on fluid applicators such as paint spray guns such that the material being applied is recirculated back to a return main via double or concentric hoses to minimise settlement of particulate matter. In such cases, a secondary advantage is the maintenance of material consistency or viscosity where such variation would adversely affect the quality of the finish applied. It has also been the case that various methods of control have been installed for coupling these hoses to the main feed lines with the aim of limiting or eliminating static or 'dead' sections of hose or piping in these systems in which settlement, and consequent blockage, could take place.These methods range from a simple system of stop-cock valves so arranged that by switching in a sequence they will create recirculation either through the applicator or spray gun, or through the system only and back to the return line, to a combination of these valves into one, composite control valve.

Not all of these systems have proven to be trouble-free and reliable in use and in every case known to the applicant, can be cleaned only by dismantling all or part of the system and then flushing with a solvent or cleaning agent.

It is an object of the invention to provide an improved design valve in which all functions are controlled by one knob or lever and in which a flushing circuit is provided which will allow this to be done without dismantling any part of the valve, applicator or spray gun and the hoses connecting them to each other.

Broadly stated the invention provides a valve for controlling a recirculating flow of fluid to a recirculating fluid delivery hose, having a first valve position in which a fluid supply line and a fluid return line are connected to feed and return sides of the hose through first flow channel means in said valve and a second position in which the fluid supply line and the fluid return line are connected together through second flow channel means in the valve and the feed and return sides of the recirculating fluid hose are isolated, wherein there is a purge fluid supply line to the valve and a third valve position in which the first and second flow channel means are in series and connect the purge fluid supply line with the feed and return sides of the recirculating fluid hose.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figures 1-3 are diagrams showing a valve according to the invention with its associated fluid delivery and return lines and with a fluid recirculation hose attached thereto; Figures 4,5 and 6 are front, side sectional and side views of a practical embodiment of the valve with the rotor in its "recirculation through valve" position, a cover plate and gasket being removed in Figure 6 to show the fluid flow loops; and Figures 7a-7d, 8a-8d, and 9a-9d are sections of the valve on the lines A-A, B-B, C-C and D--D of Figure 5 with the valve rotor in its "recirculation through hose", "recirculation through valve" and "solvent purge" positions respectively.

In Figures 1-3, a rotating valve barrel 10 rotates in a body to which is connected a fluid delivery line 12, a fluid return line 14 and a solvent line 16.

Leading from the body is a hose delivery line 18 and a hose return line 20 leading to a hose 22 having an inner tube 23 and an outer sleeve 24 by which paint may be recirculated to a spray gun. Also formed in the valve body are three fluid flow loops 25, 26, 27.

The barrel 10 is formed with bores defining three different sets of flow paths. The first set of flow paths is defined by a pair of angular passages 28, 29 that in the barrel position shown in Figure 1 interconnect fluid delivery and return lines 12,14 with hose delivery and return lines 18, 20, the other two flow paths being dormant.

In the barrel position shown in Figure 2 the passages 28, 29 are dormant and a generally Yshaped passage has its stem 30 dormant and its arms 31,32 connecting the fluid delivery and return lines 12, 14through the barrel 10, the flow passage in the third set again being dormant. In the barrel position shown in Figure 3 the fluid delivery and return lines are isolated and solvent is fed through an angular flow passage 35 of the third group to one end of the flow loop 25. The other end of flow loop 25 is connected through passage 28 to one side of flow loop 27 that serves to connect the passages 28 29 of the first group in series. The passage 29 leads to one side of loop 26 whose other side is connected to stem 30 which in turn is connected by arms 31,32 to the hose delivery and return lines.It will be noted that in this arrangement all the loops and passages are connected in series and that there is a parallel flow of solvent into the delivery and return sides 23, 24 of the hose 20. By this means, the valve can be switched from a condition where paint or other fluid circulates through the hose to a condition where paint or other fluid circulates through the valve and further to a condition where the valve and hose are flushed e.g. with solvent.

In Figures 59 the barrel 10 is supported for rotation in a central bore in a valve block 50 where it is an interference fit in a sleeve 51 of polytetrafluoroethylene or similar low friction sealing material. A key 52 (Figure 7b) prevents the sleeve 51 rotating relative to the body 50. The body 50 carries a backplate 54 by which it may be mounted in a wall mounting bracket 55 and a dowel pin 56 locates in a semi-circular slot 57 in the rear end face of the rotor 10 to limit rotation thereof to 180". The working positions of the barrel 10 are defined by a spring-loaded detent 58 that locates in pockets 59 in the rotor. The fluid delivery line 12 is provided with a fluid flow control valve 60 which can be rotated to adjust the rate at which fluid flows. The barrel 10 is connected through front cover plate 61 with a handle 62 by which it may be rotated.It will be noted that part of the loops 25,26 and 27 are formed as open channels formed in a side face of the block 50 and closed off by means of a cover plate 65 and gasket. The valve of the invention is of simple construction but is effective to allow the flow of paint or other fluid to be switched between recirculation involving the delivery hose, recirculation through the valve and solvent purging.

As apparent from Figure 4, the valve is further provided with "Off' positions that close off every port connection and each of the main function and "Off" positions are located by the spring detent 58.

The lever 62 may also be lockable and this is included mainly as a safety measure so that the lever 62 will need to be unlocked from the "recirculation-through-valve" position to be set to any other position. The main hazard would be to flood paint or solvent from the valve if the lever 62 were to be moved without the spray gun or applicator being connected.

As appa rent from Figure 4, the valve is further provided with "Off" positions that ciose off every port connection and each of the main function and "Off" positions are located by the spring detent 58.

The body 50 of the valve can be made in nickel electroless plated on to aluminium or brass with stainless steel being used for high corrosion applications. The rotating valve barrel 10 may be made in stainless steel and a fine finish imparted to ease rotation in the P.T.F.E. bush 51 in which it is designed to have an interference fit. This fit is to provide the sealing necessary between the various ports. The concentric hose outlet from the valve will be connected via the special fittings shown to create a feed 23 through the inner hose, which will be made from nylon or other such mterials, and a return 24 via the outer hose, which will be made from a suitable, flexible, solvent resistant material.

Figure 3 shows very clearly that the solvent flushing or purging is complete within the valve and, because of the branch in the design of this circuit to include both inner and outer h-)se connections 23, 24, then the hoses and the spray gun or applicator can be fully purged without disconnection. The solvent or cleaning fluid can be collected from the spray gun or applicator and discarded or filtered and reclaimed separately.

Although not shown on the circuit, it is possible to connect air or gas under pressure to the solvent purge connection via a 3-way valve so that all free solvent can be expelled from the circuit.

The regulatory valve 60 for control of the volume of fluid allowed to pass to the spray gun or applicator comprsies a simple rotating member with a cross-drilled hole. Rotation is via an internal hexagon in one end which can be operated by inserting a hexagon allen key.

The valve of the invention is designed to be mounted on a wall or flame in multiples side-byside. It can exhibit good corrosion resistance, long life maintenance-free operation due to the materials selected, easy operation by one lever, safety in use by using the lock (or detent) to prevent tampering and unique inclusion of a solvent purging facility.

Claims

1. A valve for controlling a recirculating flow of fluid to a recirculating fluid delivery hose, having a first valve position in which a fluid supply line and a fluid return line are connected to feed and return sides of the hose through first flow channel means in said valve and a second position in which the fluid supply line and the fluid return line are connected together through second flow channel means in the valve and the feed and return sides of the recirculating fluid hose are isolated, wherein there is a purge fluid supply line to the valve and a third valve position in which the first and second flow channel means are in series and connect the purge fluid supply line with the feed and return sides of the recirculating fluid hose.

2. A valve according to Claim 1, comprising a barrel rotatably mounted in a valve block by means of a resilient bearing sleeve of fluid-resistant material said sleeve being in compression to seal against the barrel and said first and second flow channel means being formed in the barrel.

3. A valve according to Claim 2, wherein the valve block has connections for the fluid supply line and fluid return line and the purge fluid supply line on an upper side of the barrel and a connection for the feed and return sides of the delivery hose on a lower side of the barrel, the said connections lying in a common plane passing through the axis of the barrel.

4. A valve according to Claim 3, wherein the first flow means comprises a pair of angular channels in the barrel that in the first valve position lead to a top-opening angular feed passage in the valve block and a bottom opening angular delivery passage in the valve body.

5. A valve according to claims 2,3 or 4, wherein the second flow channel is generally Y-shaped and is arranged such that in the second position its arms communicate the fluid supply and return lines with the stem isolated and in the third position its stem communicates through the arms with the feed and return sides of the hose.

6. A valve according to Claim 5, wherein the block is formed with first, second and third flow loops that are isolated except when the barrel is in the third position, the first loop then communicating through a third angular passage in the barrel to one end of one of the angular flow passages, the second loop communicating the other end of said one flow passage with the other of said flow passages and the third loop communicating said other flow passage with the stem of the Y-shaped passage.

7. A valve according to any preceding claim wherein the block is provided with a stopcock for regulating the flow of fluid from the fluid supply line.