GB2190199A

GB2190199A - Measuring gas pressure

Info

Publication number: GB2190199A
Application number: GB08611212A
Authority: GB
Inventors: David John Victor Smith
Original assignee: Graviner Ltd
Current assignee: Graviner Ltd
Priority date: 1986-05-08
Filing date: 1986-05-08
Publication date: 1987-11-11
Also published as: GB8611212D0

Abstract

A pressure vessel stores gas at high pressure within a helically coiled tube 6 connected to feed an outlet 22 through an electrically detonated explosive-actuated valve 18. In order to measure the pressure of gas within the tube 6, a strain gauge 40 is connected to measure the force exerted by the tube 6 which acts like a Bourdon tube and tends to straighten in response to the gas pressure. <IMAGE>

Description

SPECIFICATION Systems and methods of measuring high pressure The invention relates to systems and methods for measuring high pressure. Embodiments of the invention to be described are for measuring gas pressure in pressure vessels. Pressure vessels are used to store gas under pressure for a variety of purposes. In order to enable a large quantity of the gas to be stored in the vessel, it is advantageous to store the gas under substantial pressure, and it is desirable to be able to measure the pressure so as, for example, to detect leakage and thus to be able to determine when the gas stored in the vessel is no longer sufficient or is no longer at sufficient pressure to be useful for the purpose intended.

According to the invention, there is provided a method of measuring gas stored within a pressure vessel in the form of a curved tube containing the gas under pressure and which is connected to an output via a releasable valve, comprising the step of measuring the force exerted by the curved tube in tending to straighten in response to the gas pressure.

According to the invention, there is further provided a system for measuring gas stored within a pressure vessel in the form of a curved tube containing the gas under pressure and which is connected to an output via a releasable valve, comprising means connected to measure the force exerted by the curved tube in tending to straighten in response to the gas pressure.

According to the invention, there is still further provided a pressure vessel storing gas under pressure, for use, comprising a casing, a coiled tube within the casing and containing the gas under pressure, a gas outlet, and a controllable release valve connecting the tube to the outlet for allowing release of the gas when required for use, and including means for measuring the mechanical force exerted by the tube in tending to straighten in response to the gas pressure within it, and means for converting this measured force into an indication of the pressure within the tube.

Pressure measuring arrangements and methods according to the invention, and pressure vessels embodying the invention, will now be described by way of example only and with reference to the accompanying drawings in which: Figure 1 is a longitudinal cross-section through the pressure vessel; and Figure 2 is an end view of the vessel of Fig.

1 As shown in the Figures, the pressure vessel is cylindrical in shape and is in the form of a cylindrical casing 5. Mounted within the casing 5 is a hollow helical tube 6. The end of the tube adjacent the end 10 of the vessel is closed off and the tube is then helically wound towards the end 12 of the vessel. It passes through a charging valve member 14 and terminates in an output valve member 16.

The tube 6 contains the stored gas under very high pressure.

The output valve member 16 has an electrically detonatable explosive-actuated output valve 18 which is normally closed. In response to an electrical signal applied to electrical connections 20 (see Fig. 1), a detonator causes explosive opening of the valve and the tube 6 is thereby connected to an outlet 22, through a pipe 26 and a pressure reducing valve 28.

In operation, therefore, the stored gas is released by applying the appropriate electrical signal to the connections 20 and the gas issues at reduced pressure through the outlet 22.

The tube 6 is initially charged with the high pressure gas via the valve meinber 14 through an inlet 30 and a pipe 32.

In order to be able to monitor that the gas stored within the tube 6 is at the necessary minimum pressure, some form of pressure measurement is required.

In accordance with a feature of the invention, therefore, a suitable form of strain gauge, indicated purely diagrammatically at 40, is mechanically connected between a suitable location on the tube 6 and the casing 5. The strain gauge 40 may be of any suitable type for measuring the force acting between its points of connection. More specifically, the strain gauge 40 is arranged to measure the compressive force acting between the outside surface of one of the coils of the helix and the inside surface of the casing.

In operation, the tube 6 acts as a Bourdon tube. Thus, the high pressure gas within it tends to straighten the tube, and the force produced by this tendency, which is of course resisted by the mechanical construction of the vessel, is a measure of the gas pressure within the tube and is sensed by the strain gauge 40. Advantageously, the strain gauge 40 is of a type which produces a corresponding electrical output signal which can thus be easily extracted from the vessel and arranged to operate a suitable measuring unit. The latter may produce an output indication of the actual pressure and/or may be arranged to produce a warning output if the pressure falls below a predetermined minimum. The electrical output signal from the strain gauge would not normally be used continuously but could be interrogated periodically, on an automatic basis, or by means of a press-to-test function.

It will be appreciated that the various mechanical details of the vessel can be widely varied without departing from the scope of the invention.

Claims

1. A method of measuring the pressure of gas stored within a pressure vessel in the form of a curved tube containing the gas under pressure and which is connected to an output via a releasable valve, comprising the step of measuring the force exerted by the curved tube in tending to straighten in response to the gas pressure.

2. A system for measuring the pressure of gas stored within a pressure vessel in the form of a curved tube containing the gas under pressure and which is connected to an output via a releasable valve, comprising means connected to measure the force exerted by the curved tube in tending to straighten in response to the gas pressure.

3. A pressure vessel storing gas under pressure, for subsequent discharge therefrom, comprising a casing, a coiled tube within the casing and containing the gas under pressure, a gas outlet, and a controllable release valve connecting the tube to the outlet for allowing discharge of the gas, and including means for measuring the mechanical force exerted by the tube in tending to straighten in response to the gas pressure within it, and means for converting this measured force into an indication of the pressure within the tube.

4. A system or a pressure vessel according to claim 2 or 3, in which the force measuring means comprises a strain gauge.

5. A method of measuring pressure within a curved tube storing high pressure gas for use, substantially as described with reference to the accompanying drawings.

6. A system for measuring pressure within a curved tube storing high pressure gas for use, substantially as described with reference to the accompanying drawings.

7. A pressure vessel, substantially as described with reference to the accompanying drawings.