AU2007203037A1 - Relief valve - Google Patents

Description

POOl Section 29 Regulation 3.2(2)

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: Invention Title: Relief valve The following statement is a full description of this invention, including the best method of performing it known to me: RELIEF VALVE TECHNICAL FIELD The present invention relates to temperature, pressure and expansion relief valves, and in particular, to such relief valves for cold water and hot water systems.

BACKGROUND OF THE INVENTION Home and industrial water distribution systems distribute water to various fixtures, for example, sinks, bathtubs, showers, dishwashers and washing machines, that are located throughout the house, commercial or industrial building. A typical water distribution system delivers water from a water storage or delivery source, such as a solar heated water storage system, gas heated water storage system, instantaneous (combination) hot water supply system or cold water storage system.

Typically there will be provided at least a water pressure relief valve, but often a temperature and pressure relief valve (PTRV) or, for a cold water system, a cold water expansion control valve (ECV), between the hot/cold water unit and the various fixtures in the property.

A pressure relief valve is a safety device on a water heater or boiler or pressure tank. When the pressure in the water system builds to the point of being unsafe, the valve opens and allows steam or water to escape. Without this safety device, a tank or storage device could explode. A pressure relief valve will operate when the pressure becomes too high, perhaps due to an interruption if the water supply or a faulty thermostat. A pressure relief valve does not detect temperature increases.

Pressure and temperature relief valves, also called PTR valves are emergency safety limit devices that will prevent or relieve overheated water and pressure. Without a relief valve during an unsafe condition, the pressure inside the water supply unit, such as a tank or heated water storage device would rise to the point that the tanks/storage device may rupture or explode, this would cause potential damage to both people and property. Typically a PTR valve is designed to open when the pressure inside the tank/storage device exceeds the vessels nominated working pressure e.g. 150 psi, allowing pressure to vent safely. A PTR valve will also open if the water temperature reaches approximately 1000 C (approximately 2100 The valve will remain open allowing cold water into the tank/storage device until the unsafe condition is relieved.

Such relief valves, either PTRV or ECV relief valves are commonly mounted to the hot water/cold water unit or placed in line in piping close to the outlet from such a unit. In the case of a PTRV this safety valve releases water (and thus relieves pressure) if either the temperature or the pressure on the supply side gets too high. These valves are very important. Water heaters can become dangerous if the pressure gets too high and no valve is fitted or the valve fails to work. It is uncommon for such valves, especially older valves, to get stuck in the open position when tested using the test release mechanism used to deliberately open the valve under test. Also, such valves may weep or leak water if the valve does not close correctly or high pressure lifts the valve slightly.

These valves are typically made with a metal body, commonly brass, bronze or cast iron machined with an internal valve seat and arranged to receive a valve stem and sealing means for engagement with the machined seat. A significant problem has been identified with these valves when requiring repair or replacement. Typically, a faulty or worn valve is replaced entirely in order to ensure the correct pressure rating is achieved. This is because it is generally easier to replace the whole valve with one of a correct preset pressure rating than to take apart the original valve, replace or repair components and expect to reassemble the valve to the correct pressure rating. Complete replacement valves are pre-tested to the correct pressure rating and therefore it is generally seen to be easier to replace the whole valve. However, replacing the whole valve requires removal of the metal (brass) body or housing from the piping, which requires the gas or electricity and cold water supply to the heater unit to be turned off. Also, the fittings attaching the PTRV to the piping can oft-times be difficult to remove or may require replacing to effect a fresh seal.

Such prior art pressure relief valves are relatively expensive to manufacture, requiring casting or machining of the metal body, typically brass, bronze or cast iron, with an accurately machined valve seat and some means for aligning the valve stem or seal with the seat, which would typically be a screw thread or cylindrical receiving port also machined within the metal body. With the increasing costs of the raw metal materials, increasing production costs in machining the metal components, and not at least the time required to machine such parts, such valve bodies become increasingly expensive.

In addition, such prior art pressure relief valves and temperature and pressure relief valves are manufactured as discrete units and calibrated to a preset pressure relief point. If the valve becomes defective or fails, the entire valve is typically replaced including the metal housing. Given that the metal housing would be typically either attached directly to the water storage unit, e.g., a pressurized water heater, or less typically in the piping immediately after the storage unit, a considerable amount of disassembly and downtime of the system is required to replace the entire valve.

In the light of the above, it will be advantageous to provide a device that addresses one or more of these problems.

Reference to any prior art in the specification, whether in background section or otherwise, is not, and should not be taken as an acknowledgement or any form of admission that the prior art forms part of the common general knowledge in Australia.

SUMMARY OF THE INVENTION With the aforementioned in mind, in one aspect the present invention provides a pressure relief valve insert for a housing of a pressure relief valve for a water storage and delivery system, the valve insert including a sealing means for sealing with a cooperating member when the valve is closed and a pressure relief means for unsealing from the cooperating member when exposed to excess pressure.

A further aspect of the present invention provides a pressure relief valve insert for housing of a pressure relief valve for water storage and delivery systems, the valve insert including a valve seat and a valve seal for sealing in corporation with the seat, wherein the cartridge is configured to be removably received in the housing as a discrete unit.

Thus, advantageously, the pressure relief valve insert allows for the body or housing of the pressure relief valve to remain in situ whilst the internal valve seal and pressure relief mechanism may be removed and replaced.

Where pressure relief valves are referred to in regard to the present invention, it will be appreciated that expansion control valves (ECVs) for water systems are considered to be encompassed by and within the scope of the invention.

Preferably, the insert may include means for adjusting a pressure relief set point, which advantageously provides for adjustability of the required pressure relief point or correction of that point if the valve there is incorrectly set. However, it will be appreciated that the insert may be preset to a preselected pressure relief set point such that the cartridge can be inserted into the housing with a precalibrated pressure relief point.

A further embodiment of the present invention may provide means for opening the valve dependent upon a temperature sense to be above a predetermined temperature set point. Thus, advantageously, the insert may provide for pressure relief due to over temperature, overheating of the water resulting in over pressure. Such opening means may include a device including wax which is arranged to melt at a predetermined temperature thereby allowing the valve to open. Resolidifying of the wax may consequently close the valve once the temperature drops below a predetermined set point. The opening and closing temperature set points may differ.

Preferably, the valve insert may include means for sensing temperature, which, advantageously, allows the unitary valve cartridge to include temperature sensing as a discrete unit. However, it will be appreciated that remote temperature sensing may be utilized.

Preferably the valve insert may include a valve seal in cooperation with a valve seat, such that the cartridge does not require provision of a seal or seat on the housing. More preferably the insert may include the seal, seat and pressure relief biasing means a spring and or wax bulb, within the discrete unit.

Further embodiments of the present invention may include sealing means external of the insert such that the insert may effect a seal within a housing or body. Such sealing may be provide din the form of one or more O rings, which may reside in one or more annular or circumferential grooves around an external perimeter of a portion of the insert.

Preferably the insert may be provided as a unitary cartridge device.

0 Preferably the insert may be receivably removable from a valve body or housing. The housing or body may be permanently or removably mounted to a water system, or may be provided for fitting in piping.

More preferably the insert may be formed including plastics materials. This may help to reduce heat loss or heat transfer otherwise experienced with metal components. In addition, the valve body may be formed of plastics materials.

A further aspect of the present invention provides a pressure relief valve for a water delivery system, the pressure relief valve including a relief valve insert, the insert including a valve seal and means for biasing the seal to a closed C 10 position when the valve is closed but allowing the seal to open when the biasing means is overcome by excess water pressure within the system.

Preferably, the valve body for one or more forms of the invention may be thermally lagged or insulated by a thermal layer, coating or cover applied to the valve. Alternatively or in addition, the valve may be insulated by mounting between an outer casing/panel and the storage vessel of the water system.

Preferably the cartridge or insert may be a discrete item eg for replacement in a ready provided valve body, or may be provided within a body or housing as a complete valve. For example, a seat may be pre-provided in a water heater system, into which the cartridge fits.

Preferably, the insert or complete valve assembly may be installed between an inner water holding container eg hot water cylinder and an outer casing. Thus, advantageously, the valve may be provided with additional thermal insulation by being positioned between the cylinder and outer casing, thus helping to reduce excess heat loss through the valve body.

Preferably, the internal components of the valve insert may be removed from the housing as a unit or separately for replacement or repair etc. This can leave the escutcheon/face or mounting plate in place.

The invention will be more readily understood from the following description upon practical arrangement of various embodiments of the present invention as illustrated with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a pressure relief valve insert according to an embodiment of the present invention.

Figure 2 shows a pressure relief valve insert according to an embodiment of the present invention including a temperature sensing probe.

Figure 3 shows an exploded view of a temperature and pressure relief valve including a pressure relief valve insert according to an embodiment of the present invention.

Figure 4a shows a side view of a pressure relief valve assembly according to an embodiment of the present invention including an adjustable pressure relief set point.

Figure 4b shows a sectional view of the pressure relief valve assembly of Figure 4a with a sectioned along line B-B.

Figure 5 shows a cross-sectional view through a pressure relief valve incorporating a pressure relief valve insert according to an embodiment of the present invention and mounted to a housing attached to a water heater system.

The pressure relief valve is shown in the closed position.

Figure 6 shows a cross-sectional view of the embodiment shown in Figure though with the pressure relief shown in an open position.

DESCRIPTION OF PREFERRED EMBODIMENT Referring now to Figure 1, a pressure relief valve cartridge 10 according to a particular embodiment of the present invention can be seen. The cartridge is arranged to be inserted within a body or housing (not shown) of a pressure relief valve entire. The cartridge includes a cartridge body 11, a valve seat arrangement 12, a spring and piston arrangement 13, a pressure adjustment screw mechanism 14, and a valve easing pin The cartridge body 11 includes a circumferential groove 16 for receiving an O ring seal (not shown). Similarly, the valve seat arrangement 12 includes an annular circumferential groove 17 for receiving an O ring seal (not shown). The cartridge body 11 and valve seat arrangement 12 are connected via members 18.

The cartridge 10 is inserted into a receiving housing of the pressure relief valve (not shown) such that the O ring seals provide a water and pressure tight seal within the housing. The cartridge 10 can be retained within the valve housing by a cover or other retaining means such as a spring clip or circlip or retaining nut.

For example, a circlip may be applied to an annular groove on an internal surface of the housing immediately after insertion of the cartridge into the housing, such that the circlip bears onto the top surface 19 of the cartridge body 11 and consequently retains the cartridge 10 within the housing. Other arrangements for retaining the cartridge within the housing are envisaged to fall within the spirit and scope of the invention.

A spring and piston arrangement 13 is provided between the cartridge body and valve seat arrangement. A seal 20 is provided at a distal end thereof which engages with the valve seat to effect a seal. The spring is arranged to bias the seal 20 against the valve seat 12a such that pressure on an underside of the valve seat arrangement 12 must overcome the spring biasing pressure to lift the seal 20 to thereby provide pressure relief. In the arrangement shown, the piston is connected to the seal 20 and the piston extends through an aperture in the cartridge body 11 to provide a valve easing pin 15. Consequently, should the pressure relief valve cartridge require manual release, for testing purposes, the valve easing pin 15 can be pulled in a direction away from the cartridge body to effect lifting of the piston and seal. Alternative arrangements allow for a rotary operated easing mechanism. On release, the valve easing pin, piston and seal, are biased to a closed position via the spring. In the arrangement shown, the cartridge includes a pressure adjustment screw mechanism which is arranged to rotate to adjust preload of the biasing spring 13. In this way, a pressure release set point can be set. However, it will be appreciated that the spring may be provided to give a desire calibrated preload and consequently the pressure adjustment screw mechanism can be optional.

Figure 2 shows a similar arrangement to the embodiment shown in Figure 1. However, in this embodiment the cartridge includes a temperature sensing probe 21. When water temperature exceeds a predetermined value, the temperature sensing probe 21 sends a signal to a pressure relief mechanism, a wax cell, which effects opening of the pressure relief valve to release excess pressure caused by an expected temperature rise above a set point. It will be appreciated that the temperature set point may also be adjustable.

Figure 3 shows an exploded view of a temperature pressure and relief valve incorporating a temperature and pressure relief cartridge according to an embodiment of the present invention. The valve 30 includes a valve housing 31 for attachment to a hot water system (not shown) via a base portion 32, the housing includes an aperture 33 for receiving the cartridge assembly 34, a drain outlet 35 for excess water relieved during operation of the pressure relief valve.

The embodiment of the cartridge 34 shown in Figure 3 includes an option temperature probe 36 for sensing water temperature; the cartridge 34 is inserted into the housing 31 via the aperture 33 and retained in place by a retaining circlip 36. The cartridge includes a valve easing pin 37 and a pressure adjustment mechanism 38. Once retained in place by the circlip 36, a cylinder casing escutcheon 39 is placed over the outside end of the cartridge against the flange of the housing. A valve easing twist knob 40 is then placed over the valve easing pin 37 and attached via a washer and clip 41. If required, an information disc or cap 42 can be used to cover the washer and clip 41 and provide information or data on the pressure relief characteristics of the valve, such as pressure and temperature relief parameters and required set points.

In operation, excess pressure from the hot water system and outlet from the system to an aperture at the base 32 of the housing 31 causes the seal of the cartridge to lift and compress the biasing spring. This allows water to escape via the drain 35 until pressure is relieved to the point that the biasing spring overcomes pressure in the system and returns the seal to the seat of the cartridge. In the event an excess temperature, above 930 C (approx 2000 F) and by 990 C (2120 a wax bulb within the cartridge may be caused to melt and cause the valve to unseat, thereby also effecting pressure release caused by high temperature. In the arrangement shown, preload of the spring may be adjusted such that the required temperature and/or pressure at which the valve opens and/or closes may be adjusted.

Should the cartridge require replacement, the escutcheon and valve easing know can be removed, the circlip 36 removed from the housing and the cartridge pulled from the housing. Reassembly with a replacement fresh cartridge is a reversal of the removal procedure, without requiring special tools to remove the entire housing, and the consequential downtime of the system. If necessary or required, special tools may be needed for removal/replacement of the insert. In this way, a single housing can be fitted to each water system and a preselected cartridge inserted with a pre-calibrated opening and closing parameters for a particular hot water pressure and temperature application.

0 Thus, a manufacturer can utilize a single housing for various applications and readily insert a chosen cartridge of particular calibration for a required application.

;This alleviates the need for a variety of ratings of pressure release valves or temperature and pressure release valves as currently required.

Alternatively, the escutcheon or face plate, or mounting plate, can remain in place on the system when the cartridge insert is removed for repair or replacement.

Figure 4a shows a side view of an alternative embodiment of the present invention. The unitary cartridge 50 includes a cartridge body 51 incorporating the C 10 cartridge mechanism. A valve easing cover 52 is provided for operating the valve easing mechanism to lift the seal e.g. during testing. The cartridge 50 is arranged to be fitted into a receiving housing (not shown) of a water system. The housing may include the valve seat allowing the cartridge to be fitted to housings having a seat, or the valve seat may be included in the unitary cartridge and the cartridge received into a housing without a valve seat.

Figure 4b shows a section through line B-B of Figure 4a. This figure shows the valve seal 54, pressure spring 55, valve easing pin 56 and pressure adjustment mechanism 57. In operation, the valve seal 54 seats against a valve seat 53 of a housing when in a closed position. Excess pressure underneath the valve seat, (shown as arrow A) will lift the valve seal if the excess pressure exceeds the biasing pressure of the spring 55. This allows water to drain until the pressure drops to a point where the biasing spring can return the seal to shut the valve. Adjustment of the pressure adjustment mechanism 57 allows a preload force to be applied or released from a distal end of the spring 55 such that a chosen working pressure can be set for the valve. For example, adjusting the mechanism to compress the spring will apply an increased preload to the spring thereby requiring greater water pressure to lift the seal. Adjusting the pressure adjustment mechanism in the opposite direction will remove some preload pressure on the spring thereby allowing a reduced water pressure to lift the seal.

However, it will be appreciate that a pre-calibrated cartridge can be provided whereby a known biasing spring can be fitted, which may or may not be adjustable. The valve easing pin 56 is connected at one end thereof to the valve seal 54, which in this particular arrangement, the valve easing pin 56 has a flanged head 58 arranged to engage with a rubber or plastics material (polymer) valve seal 54. A central insert 59 sits within an end of the spring 55, and the spring 55 sits within a lower end of the cartridge body 60. The central insert helps to centralise and stabilise the spring with respect to the lower end of the cartridge body 60. The cartridge upper body 61 receives the pressure adjustment mechanism and the valve seal arrangement of the lower end of the body The lower end 60 is slidably movable relative to the upper body 61. Sealing between these components can be effected by an O ring seal, which can be provided to reside in annular groove 62. At a distal end of the valve easing pin 56 is attached the valve easing pin cover 52. In this arrangement, pulling on the valve easing pin cover 52 in a direction away from the valve seat and seal will lift the valve bucket seal 59 to allow manual release of water and/or pressure for testing purposes.

Figure 5 shows a sectional view of the embodiment of Figures 4a and 4b mounted between an outer wall 71 of a hot water storage tank 72 and an outer wall 73 of a casing 74. The valve 70 has the cartridge valve 70b within a valve body or housing 70a. The valve is shown in a closed position with the valve seal in contact with the valve seat 76.

Figure 6 shows the same pressure relief valve 70 with the cartridge open. The valve seal 75 is lifted from the valve seat 76 due to excess water pressure within the tank 72. Water then drains through drain aperture 77 until sufficient pressure is relieved and the valve can close under the action of spring 78.

Heat loss is a concern in water heater systems. Consequently, it would be beneficial to thermally insulate the valve. In Figures 5 and 6, the outer casing 73 provides thermal insulation for the valve by having the valve mounted within the casing i.e. on the storage vessel side of the casing wall. The valve may be additionally insulated by covering or coating the valve with a thermal layer or lagging. It will be appreciated that the valve may be mounted externally of the casing, in which case, the valve may also be thermally insulated eg by additional thermal lagging or coating or addition of a thermal cover. Alternatively or in addition, the valve may be positioned between an inner water vessel (cylinder) and an outer casing to beneficially provide additional thermal insulation by 11 reducing heat loss from the valve body or housing positioned within the outer casing. This advantageously helps reduce heating costs and allows the valve to be mounted directly or close to the cylinder. Also, in zero or sub-zero temperatures, the valve is protected from extreme cold conditions and potential failure or seizing.

Claims (12)

1. A pressure relief valve insert for a housing of a pressure relief valve for a water storage and delivery system, the valve insert including a sealing means for sealing with a cooperating member when the valve is closed and a pressure relief means for unsealing from the cooperating member when exposed to excess pressure.

2. A pressure relief valve insert for a housing of a pressure relief valve for water storage and delivery systems, the valve insert including a valve seat and a valve seal for sealing in corporation with the seat, wherein the cartridge is configured to be removably received in the housing as a discrete unit.

3. A valve insert as claimed in claim 1 or 2, wherein the insert is configured to be removably received in the housing as a discrete unit.

4. A valve insert as claimed in any one of the preceding claims, wherein the valve insert includes means for adjusting a pressure relief point setting.

5. A valve insert as claimed in any one of the preceding claims, wherein the valve insert further includes means for opening the valve dependent upon a temperature sensed to be above a predetermined temperature set point.

6. A valve insert as claimed in any one of the preceding claims, wherein the valve insert further includes means for sensing temperature.

7. A valve insert as claimed in claim 5, further including means for adjusting the temperature relief set point.

8. A valve insert as claimed in any one of the preceding claims provided as a unitary cartridge device.

9. A pressure relief valve including a pressure valve insert according to any one of the preceding claims. 1 A pressure and temperature relief valve including a pressure relief valve insert according to any one of the preceding claims.

11. A valve as claimed in any one of claims 9 or 10 including a unitary cartridge insert.

12. A valve insert as claimed in any one of claims 1 to 8 arranged to be mounted between an inner vessel and an outer casing of a water storage vessel.

13. A valve as claimed in claim 9 or 10, arranged to be mounted between an inner vessel and an outer casing of a water storage vessel. DATED this 28 th day of June 2007 PETER JOHN MORRIS WATERMARK PATENT TRADE MARK ATTORNEYS GPO BOX 2512 PERTH WA 6001 AUSTRALIA P26652AU00