AU775408B2 - Outlet pressure limiting valve - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicant: Actual Inventor: Address for Service: Invention Title: Details of Associated Parent Application: Trevor Thomas ESPLIN and Patricia Anne ESPLIN Trevor Thomas ESPLIN FRASER OLD SOH-N Patent Attorneys Level 6, 118 Alfred Street MILSONS POINT NSW 2061 "Outlet Pressure Limiting Valve" 37634/97 Ah f1ollo1WIng stLatLcm-cntL is a ftull L101-1 CALsnvn~n n ;n the bes't meto of performing it known to us: 4 S 0* 5555

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OUTLET PRESSURE LIMITING VALVE.

In a variety of different situations, fluid is often required to be delivered at a flow rate within a particular range of flow rates and at a pressure less than or equal to a maximum set pressure regardless of the dynamic or static supply pressure of the fluid supply. In the majority of such cases, pressure regulators are normally required to be installed in order to provide the required fluid flow parameters for these specific applications. However, there are occasions when normal fluid regulators are too expensive. For 10 example, conventional diaphragm type regulators are both expensive and bulky. Also they do not provide any method of indicating the presence of a system failure. Similarly, conventional plunger type regulators are also expensive and bulky and rely heavily on an adjustable spring mechanism to provide the level of required performance. The present invention relates 15 particularly to providing an inexpensive arrangement for the control of fluids for certain domestic and commercial uses, whereby the amount of fluid that flows through the device and the pressure of that fluid can be kept within certain defined limits notwithstanding changes in the supply system's pressure.

BACKGROUND OF THE INVENTION.

One particular application for the present invention relates to the flow of water from a town water supply or similar, into water conditioning apparatus such as water filtration devices and reverse osmosis units as well as commercial or domestic hot water heaters. It has been found that for the cartridge type filters which are the plumbed in under sink variety for the plumbed in reverse osmosis units, and for hot water cylinder type capacity heaters, an uncontrolled or unmonitored connection to a town water supply can introduce a variety of unwanted complications to the end user of these devices. These complications can range from the annoying to the dangerous.

Many water supply authorities around the world require that once water has passed into the various filtration chambers of water conditioning apparatus, an effective method be provided in order to prevent any back feeding of the residual sludge into the drinking water supply line. To meet this requirement, single or dual check valves are normally installed between the S town supply and the filtration cartridges. However, it has been found that providing a set-up of this nature leads to annoying failures whereby mains pressure water is allowed to be vented in an uncontrolled manner. This causes flood type damage to the property's internal areas.

15 This venting is caused by the fact that when water hammer occurs the housings which encapsulate the various filtration members momentarily become pressurised by the shock wave which caused the water hammer to occnr.r. As th pr nresure i n the-e hnousing ri e the non-rethrn valve(s) prevent the pressure from being discharged back down the mains supply line. Therefore, sustained water hammer in the system can cause a pressure build up within the housings which exceed their designed pressure ratings.

Once these housings (or their seals) fail, water is vented to the atmosphere in an uncontrolled manner. This normally results in much inconvenience to the householder as well as various insurance claims in order to rectify the resulting damage.

The present invention seeks to overcome these problems by providing a pressure limiting device which will limit the maximum pressure which these units will experience.

SUMMARY OF THE INVENTION.

In accordance with a first aspect of the present invention, there is disclosed a pressure limiting device comprising a tube having an inlet end and an outlet end, a nonreturn valve biased towards the closed position and located within said tube adjacent said inlet end, a piston having a fluid passageway there through and being mounted for reciprocal motion within said tube, the outlet end of said piston having a larger area exposed to fluid pressure in said outlet than the corresponding area of the inlet end of said piston, first bias means to bias said piston towards said outlet, and said non-return valve being closable by movement of said piston towards said inlet end.

In accordance with a second aspect of the present invention there is disclosed a method of operating a pressure limiting device, said method being substantially as herein described with reference to the drawings.

The term "comprising" (and its grammatical variations) as used herein is used in the inclusive sense of"having" or "including" and not in the exclusive sense of"consisting only of'.

oooo oooO BRIEF DESCRIPTION OF THE DRAWINGS Three embodiments of the present invention will now be described with reference to the drawings in which: Fig 1 is a longitudinal cross-sectional view of a pressure and flow control device of a first embodiment, suitable for use with water supply filters and other similar water conditioning devices, Fig 2 is a similar view ofa device ofa second embodiment suitable for controlling "30 the supply of water to hot water systems and the like, an oo 000002 Fig 3 is a view similar to Fig 1 but of a device of a third embodiment suitable for use with water supply filters and other similar water conditioning devices.

DETAILED DESCRIPTION The fluid flow and pressure control valve 1 illustrated in Fig 1 takes the form of a body 101 which has an inlet end 103 which contains an inlet orifice 104 and an outlet end 105 which contains an outlet orifice 106. The outlet orifice 106 is internally threaded at 139. The orifices 104 and 106 are 10 joined by an interconnecting passageway 107. The interconnecting passageway 107 takes the form of at least two boreholes which are in a stepped relationship with each other wherein the outlet side borehole 108 is of a larger diameter than the smaller diameter inlet side borehole 109 and the central axes of both the different diameter boreholes are substantially 15 coaxial. An inlet passageway 110 connects the inlet orifice 104 to the smaller diameter bore 109.

Within the arrangement of stepped boreholes is located a stepped piston 111 which makes a sliding and sealing contact with both internal surfaces of the major and minor diameters of the stepped boreholes by means of 0-rings 112 and 113. Between the inlet side of the larger diameter of the stepped piston and the outlet side of the end of the smaller diameter of the stepped borehole is formed a controlling chamber 114, the volume of which varies according to the position of the stepped piston 111 within the stepped boreholes 108, 109. It should be noted that an intermediate borehole 115 can be included for ease of manufacture.

Located near the outlet end of the major diameter borehole 108 is a retaining means 116 which limits the travel of the stepped piston 111 in a direction away from the inlet end 103. Located within the stepped piston 111 is a coaxial flow control passageway 117. Located on the stepped piston 111 and in co-operation with the flow control passageway 117 is a valve seat component which in this case is an O-ring 118 which is positioned within a recess 119 on the inlet end of the stepped piston 111. The inlet end of the body section contains an external thread 120 for screw threaded connection to other fluid transport mechanisms. Between the sliding and sealing 10 contacts of the major and minor diameters of the stepped piston 111 is a bleed hole 121 in the body section 102 which leads from the controlling chamber 114 to the outside of the body section 102. Located in conjunction with the bleed hole 121 is a sealing device 125 which can totally block the movement of fluids from the pressure chamber flowing through the exit orifice 122 of the bleed hole 121 to the outside of the body section 102.

Located on either side of the exit orifice 122 of the bleed hole 121 on the S" surface of the body section 102 are two sealing grooves which are axially aligned with the central axis of the hody section and within each of which is contained an O-ring 123 and 124. A safety ring 125 is positioned such that 20 it makes a sliding and sealing contact with the O-rings 123, 124 in the two sealing grooves.

In one preferred embodiment shown here, the body section has an external step 126 whereby the outer diameters of the two sealing grooves are of different sizes. The internal section of the safety ring 125 has two matching stepped diameters 127 and 128 which allow the safety ring 12 to make a sealing contact with each of the sealing O-rings 123, 124. When the safety ring 125 is in its sealing position the stepped sections provide a stop position 129 for the safety ring. There is an indicator 130 present on the body section 102 whereby when the safety ring 125 is in its stop position, the indicator 130 is concealed. Any substantial build up of fluid pressure in the bleed tube causes the safety ring 125 to move away from the stop position due to the different diameters of the sealing O-rings and the indicator 130 is revealed. There is a safety ring stop 131 attached to the external surface of the body section 102 to limit the amount of travel of the safety ring when the indicator 130 is exposed.

In another preferred embodiment wherein the two sealing 0-rings 124, 125 are the same size, should any fluid discharge occur from the bleed hole 121 when any substantial external manual movement of the safety ring 125 happens which is sufficient enough to expose one of the two sealing O-rings, 15 the valve mechanism can be determined to have failed. In this case, there is a stepped projection 132 on the external part of the body section 102 wherein when the safety ring 125 comes to rest in a home position it is prevented from anv fuirther Iongnhidinal movement and it effectively "prevents fluid in the bleed hole from communicating freely with the atmosphere.

Located within the inlet is a controlling ingress orifice 133 which limits the amount of fluid flowing through the device. It should be noted that in this preferred embodiment, of all of the various internal fluid passageways within this device, the controlling ingress orifice 133 is the smallest in diameter and effectively limits the dynamic flow of fluid through the device.

Also, contained within the inlet is a ball and spring which constitute a non- 8 return valve 134. A fluid termination pin 135 is located within the inlet and projects into the smaller borehole 109. The fluid termination pin 135 has an internal passageway 136 which allows fluid to flow from the inlet passageway to the smaller stepped borehole 109. The fluid termination pin 135 is co-axially aligned with the central axis of the device. The fluid termination pin 135 is positioned so that it may come into contact with the valve seat component 118 on the stepped piston 111. The stepped piston 111 is biased towards the outlet end 105 of the body 102 by means of a spring 137. Preferably the spring is a conical compression spring whereby 10 the rate of compression of the spring varies as the spring moves through its range of compression When an increase in fluid pressure at the outlet side of the stepped piston 111 occurs above the combined pressure of the fluid and the pressure of the 15 biasing means 137 on the inlet side of the stepped piston, the stepped piston 111 moves towards the inlet 104 of the body section 102. As the stepped S' piston 111 moves fully to the inlet 104 of the body section 102, the fluid termination pin 135 comes into engaging contact xith the valve seat component 118 as is shown below the centre line in Fig 1. This closes the non-return valv 3 The section of stepped piston 111 above the centre line in Fig 1 shows the open position of the device with the non-return valve 138 in an open position as would be the case if fluid were flowing through the device.

In Fig 2 an alternative embodiment is illustrated which is basically similar to Fig 1 and therefore only the differences will be discussed. In Fig 2 the flow control passageway is stepped and has within its length at least two different size diameters 201 and 202. The flow control passageway valve shaft 203 can protrude proud from either end of the flow control passageway. The valve shaft contains a valve seat O-ring 204 which can make a sealing contact with the valve seat component. The valve shaft 203 is biased away from the valve seat component by a spring 205. An increase of fluid pressure on the outlet side of the stepped piston above the pressure of fluid combined with the pressure of the biasing means on the inlet side of the stepped piston causes the stepped piston to move towards the inlet side of S: 10 the body section. When the stepped piston moves towards the inlet side of its limit of travel, the valve shaft comes into an interfering contact with an inlet stop component 206 such as a mesh screen. When the valve shaft comes into an interfering contact with the inlet stop component 206 and the stepped piston continues to move towards the inlet side of the body section, oei the valve shaft's valve seat O-ring 204 makes a sealing contact with the valve seat component 207. On the outlet side of the stepped piston's flow control passageway is a restriction orifice 208 through which projects the outlet end of the valve shaft 203.

S 20 When the fluid pressure on the outlet side of the stepped piston is less than the pressure of the fluid combined with the pressure of the biasing means on the inlet side of the stepped piston, this causes the stepped piston to move towards the outlet side of the body section. As the stepped piston moves towards the outlet end of the body section, the outlet end of the valve shaft comes into interfering contact with an outlet stop component 209 such as a mesh screen. As the stepped piston arrives at its limit of travel at the outlet end of the body section, the outlet end of the valve shaft's interfering contact with the outlet stop component ensures that the seal between the valve seat O-ring 204 and the valve seat component is broken as is shown above the centre line. This device can be installed between a town water supply and a water conditioning apparatus in order to limit the maximum static water pressure experienced by such an apparatus.

Turning now to Fig 3, another embodiment similar to Fig 1 is illustrated.

The same numbering system as used in Fig 1 is utilized in Fig 3 save that all numbers are increased by 200. The main difference between Figs 1 and 3 is S: 10 that fluid termination pin 135 is replaced by a fluid termination shaft 335.

The fluid termination shaft 335 is located within the inlet passageway and projects towards the inlet passageway non-return valve 334. The fluid termination shaft 335 has an internal passageway 336. The fluid termination shaft 335 is positioned so that it is able to come into contact with the inlet passageway non-return valve 334. The stepped piston 311 is biased towards the outlet end 305 of the body by means of a spring 337. When an increase ,C mae,#r at, nnpt nictnn I II of fluid pressure on ti outlet slude U t lart1 ui.e s1C rr-- rICU-- occurs above the combined pressure of the fluid and the pressure of the S" 20 biasing means on the inlet side of the smaller diameter of the stepped piston 311 and the fluid pressure on the inlet side of the inlet passageway nonreturn valve 334, the stepped piston 311 moves towards the inlet 304 of the body section. As the stepped piston moves fully to the inlet of the body section, the fluid termination shaft 335 comes into engaging contact with the inlet passageway non-return valve 334 and forces it to its closed position as is shown below the centre line in Fig 3.

11 Contained within the flow control passageway of the movable piston 311 is a second non-return valve 338 which again utilizes a ball or sphere. The ball 338 is biased towards the inlet by a spring. The end of the spring not in contact with the ball 338 is retained by a washer (not illustrated) adjacent the outlet end of the piston 311 and abutting the stops 316. The section of stepped piston 311 illustrated above the centre line in Fig 3 shows the open position with the non-return valve 338 in an open position as would be the case if fluid were flowing through the device.

o 10 In operation, where the inlet pressure is below a predetermined pressure, water (or a fluid) can flow through the inlet orifice 133, 333 and thus through the device as a whole. The size of the inlet orifice substantially controls the flow rate. In the event of an increase in pressure at the inlet, due to water hammer for example, this pressure increase is applied to the outlet 15 but is throttled by the size of the inlet orifice 133, 333. As the pressure at the outlet rises, the inlet non-return valve 134, 204, 334 is operated thereby closing off the inlet. In addition the safety ring 125, 325 is operated so that the indicator 130. 330 is revealed. This explains to the user why the flow has stopped. The user is then able to lower the outlet pressure (for example by drawing water from the filter appliance down downstream from the outlet 106, 306). This has the effect of re-setting the device since the piston 111, 311 moves towards the outlet to thereby allow the inlet valve 134, 334 to reopen.

Thus, if the high inlet pressure is only transitory, as in the case of a water hammer, the device substantially re-sets itself automatically. However, the downstream device has been shielded from the high inlet pressure.

12 If the high inlet pressure is sustained, the inlet valve 134, 334 is again closed and no flow is permitted. Again the downstream appliance is protected and the indicator 130,330 indicates the cause of the problem.

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Claims (14)

1. A pressure limiting device comprising a tube having an inlet end and an outlet end, a non-return valve biased towards the closed position and located within said tube adjacent said inlet end, a piston having a fluid passageway there through and being mounted for reciprocal motion within said tube, the outlet end of said piston having a larger area exposed to fluid pressure in said outlet than the corresponding area of the inlet end of said piston, first bias means to bias said piston towards said outlet, and said non- return valve being closable by movement of said piston towards said inlet end.

2. The device as claimed in claim 1 wherein said piston inlet end has a first sealing means to seal same against the interior of said tube, said piston outlet end has a second sealing means to seal same against said tube interior, said first and second sealing means and said tube interior defining a volume of adjustable size, said volume being in fluid communication with a pressui-e indicating device observable from the exterior of said tube wherein said 20 pressure indicator device indicates the position of said piston within said tube.

3. The device as claimed in claim 2 wherein said pressure indicating device comprises a sleeve reciprocably slidably mounted on the exterior of said tube, having third and fourth sealing means spaced to either side of a port providing said fluid communication, said sleeve and tube exterior being :o °i ooo.o* 14 shaped to permit said tube to slide along said tube interior in response to the pressure within said adjustable volume.

4. The device as claimed in claim 3 wherein the position of said sleeve constitutes said pressure indicating device.

The device as claimed in claim 4 wherein said tube includes an indicium occluded or revealed by movement of said sleeve.

6. The device as claimed in any one of claims 3 5 wherein stop means are provided on said tube to limit the sliding extent of said sleeve.

7. The device as claimed in any one of claims 1 6 wherein a valve controller is interposed between said non-return valve and said piston and is movable by said piston to close said non-return valve.

8. The device as claimed in any one of claims i 7 wherein said non- return valve comprises a ball within said tube, and biasing means to urge o• .20 said ball against the flow direction towards a valve seat orifice.

9. The device as claimed in any one of claims 1 7 wherein said non- return valve incorporates an O-ring engageable with said piston. .e

10. The device as claimed in any one of claims 1-7 wherein stop means are provided in said tube to limit the extent of movement of said piston. .oe°.o

11. The device as claimed in any one of claims 1-8 wherein said piston incorporates a second non-return valve.

12. The device as claimed in any one of claims 1-11 wherein said inlet end has a small orifice to limit flow through said device.

13. A pressure limiting device substantially as herein described with reference to any one of the drawings. 0

14. A method of pressure limiting, said method being substantially as herein described with reference to the drawings. Dated the 10th day of May, 2004. T. T. P. A. ESPLIN 0 S. *SSS S FRASER OLD SOHN Patent Attorneys for the Applicant 3226B