GB2035515A

GB2035515A - Valve assembly

Info

Publication number: GB2035515A
Application number: GB7936449A
Authority: GB
Original assignee: Biro Fils
Current assignee: Biro Fils
Priority date: 1978-10-23
Filing date: 1979-10-19
Publication date: 1980-06-18
Also published as: FR2439919B1; IT1119459B; IT7969066A0; NL7907796A; JPS5597584A; FR2439919A1; DE2942808A1

Abstract

A tap for closing tanks for storing gas under high pressure comprises a lift valve member 5 of large diameter, with a lift valve member 11 of small diameter controlling a passageway through its centre which is intended to provide for decompression of a chamber 2 within which the first valve member 5 is slidably mounted. The peripheral surface of the lift valve 5 is grooved to permit flow of gas from the tank to the chamber 2, the cross-section of this flow path being smaller than that through the valve member 5. <IMAGE>

Description

SPECIFICATION Tap with a clack valve for tanks for storing gas under high pressure The present invention concerns a tap includ ing a valve for tanks for storing gases under high pressure, in particular CO2. Industry uses gases which are stored in tanks under high pressure, the gas being taken off as required.

Such tanks comprise taps which can be of a barrel type, a flap valve type, a piston type, or a clack valve type. We are only concerned herein with the clack valve type tap which forms the only system which makes it possible to provide for satisfactory sealing over a long period under high pressure.

Generally, in such an arrangement, the clack valve member is disposed on the tank side so that the pressure obtaining in the tank applies the valve member against its seat. In this way, the force applied to the clack valve member increases and the valve member is applied more firmly against its seat, thereby to provide a perfect seal, in proportion as the presssure of the gas stored in the tank rises.

However, this arrangement, while being excellent from the point of view of sealing of the valve, gives rise to difficulties. The most serious is that the force required for lifting the clack valve member in order to open the tank, as is required for discharging the stored gas, is directly proportional to the gas pressure applied to the section of the valve member. It is for this reason that in the present state of the art clack valve type taps which are required to provide for discharging gas which is stored under high pressure in tanks are of a diameter which rarely exceeds 1 2 millimetres.

Other systems have been envisaged, which make it possible to have a greater flow diameter, but these systems do not permit the valve to be closed in the course of operation, after the valve has been opened. Numerous difficulties are encountered if the aim is to produce a tap with a clack valve of large section, which can be opened and closed manually while the gas is flowing therethrough.

Accordingly the present invention provides a tap including a clack valve, for tanks for storing high-pressure liquefied gases, including a clack valve member of large diameter, with, in its centre, a second clack valve member of small diameter, which is intended to provide for decompression of a chamber within which the first clack valve member is displaceably mounted, the opening action acting firstly on the second small-diameter clack valve member in order to produce decompression of the said chamber, and then acting on the first large-diameter clack valve member when decompression of the chamber is effective.

Such a tap has a large section in order to provide a substantial flow rate and the clack valve can be operated with a very low force so that the valve can be actuated manually or mechanically (or pneumatically), with a very small amount of power. The valve may be opened or re-closed as many times as may be required during discharge of the stored gas.

The clack valve type tap of the invention makes use of a decompression phenomenon.

It comprises a cylindrical clack valve member proper, which is of large diameter, which, in its centre, comprises a second clack valve member of small diameter, which is intended to provide for decompression of the chamber within which the clack valve member proper is displaced, in order to permit the clack valve to be opened with a small amount of power, said clack valve members being held in position by coaxial springs; the assembly being controlled by a control rod which acts firstly on the small-diameter clack valve member after decompression of the chamber of the clack valve.

The invention will be better appreciated from the following description and from study of the accompanying single figure drawing which shows a view in cross-section of a clack valve type tap according to the invention.

Referring to the accompanying drawing which shows a view in section of the tap according to the invention, it will be seen that the tap comprises a tap body 1 comprising a cylindrical chamber 2 which communicates with an orifice 3 of the high pressure gas storage tank, and an outlet orifice 4. Disposed within the chamber is a cylindrical piston 5 which forms a clack valve member which is slightly smaller in diameter than the chamber 2, being provided with annular grooves 6 and a sealing gasket means 7 which is intended to co-operate with a clack valve seat 8 which is disposed towards the outlet orifice 4, under the action of a spring 9 which bears against the end 2a of the chamber 2 and against the rearward face 5a of the piston 5.

A cylindrical orifice 10 is tapped within the piston 5, at its centre. The cylindrical orifice 10 receives a second clack valve member 11 of small diameter, comprising a sealing gasket means 1 1 a. The second clack valve member 11 is held against its seat by means of a spring 1 2 which bears against the end of a cylindrical member 1 3 which is screwed into the orifice 10 in the piston 5, the seat of the clack valve member 11 being formed by the end 1 4a of an annular member 1 4 which is screwed to the other end of the orifice 10 in the piston 5, while also serving for securing the sealing gasket means 7 of the piston 5.A control rod 1 5 which bears against the clack valve member 11 is slidable within the member 14; the control rod 1 5 comprises a passage 1 spa in order to communicate the chamber 2 with the outlet orifice 4 and a flat 1 sub which is intended to come into contact with the member 14. The control rod 1 5 is actu ated in known manner by means for example of a trigger member 1 6 or any other arrange ment.

The assembly of this mechanism is dis posed within the tap body 1 in the chamber 2 which is closed by a plug 17, being screwed into the tap body.

In the closed position, the pressure of the stored gas acts by way of the orifice 3, passing into the chamber 2 by way of the grooves or channels 6 on the rear of the piston 5 and the valve member 11, causing them to bear against their respective seats 8 and 14a, with a force which increases as the pressure rises.

The clack valve according to the invention operates in the following manner: By acting on the trigger member 16, a force is applied to the control rod 1 5 which acts on the small-diameter clack valve mem ber 11, moving it away from its seat 1 4a The compressed gas which is in the chamber 2 passes by way of the orifice 1 5a and flows into the outlet orifice 4, causing decompression of the chamber 2, the rod 1 5 continuing its movement under the action of the trigger member 16, so its flat 1 spa comes to bear against the end of the member 14 and causes displacement of the piston 5 and movement thereof away from the seat 8, freeing the gas over the entire section of the clack valve.If the trigger member 1 6 is released, the pressure of the springs 9 and 12, which is added to the pressure of the gas passing through the annular grooves 6, causes the valves 5 and 11 to close.

It will be appreciated that, when the clack valve type tap according to the invention is to be opened, the force is first transmitted to the central small-diameter clack valve member 11 which requires a very small amount of power.

It should be noted however that the flow section of the central valve member 11 is greater than the annular flow section of the piston 5, the effect of which, when the valve is opened, is to decompress the chamber 2, and in consequence no longer to expose the cross-sectional area of the piston 5 to the pressure of the gas, movement of the piston 5 then being produced by a negligible force.

This arrangement can be opened and closed as desired, which is particularly advantageous in particular for using CO2 which is stored under high pressure, for fighting fires.

Claims

1. A tap including a clack valve, for tanks for storing high-pressure liquefied gases, including a clack valve member of large diameter, with, in its centre, a second clack valve member of small diameter, which is intended to provide for decompression of a chamber within which the first clack valve member is displaceably mounted, the opening action acting firstly on the second small-diameter clack valve member in order to produce decompression of the said chamber, and then acting on the first large-diameter clack valve member when decompression of the chamber is effective.

2. A tap according to claim 1, having a chamber which communicates with the pressure gas tank and with an outlet orifice, within which chamber is housed a cylindrical piston of large diameter which forms the clack valve member proper, co-operating with a seat disposed at the gas outlet orifice side, under the action of a spring which bears against the valve member and against the end of the chamber, said clack valve member comprising in its centre a second clack valve member of small section which is actuated by a cylindrical rod having an orifice so as to communicate the chamber of the first clack valve member with the outlet orifice to permit decompression of the assembly, the rod then providing for opening of said large-section clack valve member.

3. A tap according to claim 2, in which the large-diameter clack valve member proper has annular grooves so that the gas under pressure can pass from the front to the rear of said clack valve member and apply it firmly against its seat.

4. A tap according to claim 2, in which the flow section of the second clack valve member is greater than the section of the annular passage of the clack valve member proper.

5. A tap including a clack valve, for tanks for storing high-pressure liquefied gases, substantially as hereinbefore described with reference to the accompanying drawling.