GB2225089A - Pressure switch safety valve - Google Patents

Abstract

In systems for supplying combustible gases and other fluids, a safety valve is used of the type comprising a membrane pressure switch 13-16, a stem 21 arranged in a chamber 5 and provided with a shutter 23 which is actuated by a spring 25 and latched open under the control of the membrane 14, and a labyrinth passage 7 for the gas flow having a port 11 adapted to be closed by the shutter 23. The chamber 5 with its associated stem 21 and the labyrinth passage 7 are accommodated in a single body 4. Such a valve can be produced at low cost without using gaskets which are susceptible to leaks. <IMAGE>

Description

"Pressure Switch Safety Valve" This invention relates to a pressure switch safety valve, and is concerned more particularly, but not exclusively, with such a valve for systems for supplying or distributing combustible gases or other fluids, the combination and configuration of the parts of which provide the valve with particularly useful characteristics.

As is known, in combustible gas and the like supply systems the combustible gas or other fluid must be supplied to the user devices at a pressure within preset pressure limits, which can vary depending on requirements.

To that end, valves are conventionally used which are coupled to a pressure adjusting/reducing unit including a bottom chamber which is coupled, through a small pipe, to the valve central body, said valve being associated with a closing piston for closing the gas or other fluid supplying duct. In other words, there is usually provided a pressure adjusting/reducing unit associated with the valve having a chamber through which said gas or other fluid flows. As the pressure in said chamber increases, the pressure switch membrane and a piston coupled to this membrane are raised.

ss the piston is raised, the valve is actuated to shut off, by means of a spring member, the gas or other fluid supply duct.

Renown devices tor the above mentioned application comprise two different parts and,more specifically,a first part which rorms the pressure switch proper and a second part which forms the valve ant to which there are coupled the inlet and outlet for the gas being controlled.

These knom devices have a very complex and expensive structure because,inter alia,of the need or properly assembling the two mentioned parts.

Zhe main object or the present invention is to provide such a safety valve,of the pressure switch type, in particular for combustible gas or other fluid supply systems, which is so designed and arranged as to overcome the above mentioned drawbacks.

This and other objects of the invention will become more apparent hereinafter to those skilled in the art from the following disclosure.

Ihe safety valve,in particular for cotbustible gas or other fluid supply systems, according to the invention, is of the type comprising a membrane pressure switch,a stem with shutter,affected by a spring,arranged in a chamber and controlled by said membrane,and a gas flow labyrinth passage,having a port to be closed by said stem shutter, and being essentially characterized in that said chamber and related stem and said labyrinth passage are held in a single body.

More specifically, the axis of the stem is perpendicular to the gas passage and the port associated with the labyrinth is parallel to the shutter of said stem.

According to a further characteristic,the axis of the stem chamber is parallel to the laying plane of the membrane.

The invention is illustrated by the sole crosssectional enclosed view.

With reference to the figure, the valve according to the invention, indicated generally at the reference number l,is coupled to a conventional pressure adjusting unit, generally indicated at 2, through a small tube 3.

The valve 1 essentially comprises a body 4 deflning,in an integral unit,an inner chamber 5 which can be closed at the top by a threaded ring nut 6 and perpendicular to the longitudinal axis of a gas passage or duct, indicated generally at 7,having an inlet 8 coupled to the source of said gas and an outlet c communicating with said pressure adJusting unit,2.

The duct or passage 7 is provided with a parting element 10 which defines a labyrinth including a port 11.

As shown in the figure, the right portion of the body 4 is provided with a coupling member 12 and a passage 12' for coupling the small tube 3, whereas the left portion of said bod 4 is provided 'with an outer chamber 13 delimited by a membrane 14 held in position by a cover 15 restraining a spring 16 for calibrating, through a screw 17,said membrane 14.

With the membrane 14 surface facing the chamber 13 there is rigid a rod 18 passing through an opening 19 and entering the chamber 5.A passage 20 communicates the chamber 13 and 5 with one another.

Inside the chamber 5 there is axially arranged a stem 21 which is tightly guided at the top by the ring nut 6 and is tightly guided at the bottom by a sealing ring nut 22. The bottom end portion of the stem 21 bears a shutter member 23 provided for cooperating with the port or opening ll;with the middle of the stem 21 there is rigid a ring body 24 counterbiassed by a spring 25 arranged between said body 24 and ring nut 6. The top end of the stem 21, outside or the ring nut 6,has a male thread 26 the pitch of which corresponds to the pitch of the female thread of a closing or sealing member 28 for said ring nut 6.

At a nominal oFeration position the stem 21 is held in the shown raised position because of the engagement of the rod 18 with the bottom portion of the ring body 24 and the spring 25 is therefore compressed. Within the chambers 5 and 13 will be present a pressure,from the adjusting unit 2 through the small tube 3, within the calibrating limits of the spring 16.

If the pressure increases beyond a provided limit value, then the membrane 14 will be displaced aga'nst the counterbiassing sprinr lb and the rnd 15 withdrawn to cause the stem a1 to shut off, through the spring 25 and stem shutter 23,the port 11, so as to interrupt the gas flow.

Then, after having adjusted the pressure again, the stem 21 will be re-energized by turning the closing member 28,screw engaging the threads 26 and 27 and raising said stem so as to affect the rod 18 to restrain again said stem in its energized condition through the spring 16.

broom the above disclosure it should be apparent that the body 4 and passage 7 form an integral unit, with a great reduction of the cost and without the need of using gaskets which, as is known, would be easily susceptible to leaks.

Claims (8)

1. A safety valve of the type comprising a membrane pressure switch, a stem arranged in a chamber and provided with a shutter which is actuated by a spring under the control of the membrane, and a labyrinth passage for the gas flow having a port adapted to be closed by said shutter, wherein said chamber with its associated stem and said labyrinth passage are accommodated in a single body.

2. A valve according to claim 1, wherein said stem has an axis perpendicular to the labyrinth passage, and said port is parallel to the shutter of said stem.

3. A valve according to claim 1 or 2, wherein the axis of the chamber with its associated stem is parallel to the peripheral plane of said membrane.

4. A valve according to the preceding claim, wherein the membrane chamber is integral with said body.

5. A valve according to any preceding claim, wherein said stem is provided with a lug cooperating with a rod rigid with said membrane, said rod penetrating said chamber containing said stem.

6. A valve according to any preceding claim, wherein the end of said stem opposite to said shutter is provided with a gripping member for energising said stem.

7. A valve according to claim 5 or claim 6 when appended to claim 5, wherein said stem is guided in said chamber by a top sealing ring and a bottom sealing ring, a spring being arranged between said top sealing ring and said lug.

8. A safety valve substantially as hereinbefore described with reference to the accompanying drawing.