GAS METER AND METHOD OF ASSEMBLY

Abstract: Difficulty is found in assembly of a one-way valve into a gas-flow tube of a gas meter. This invention provides for assembly of the tube (13) and valve (15) on opposite sides of an interior wall (12). A grommet (22) of carefully chosen dimensions is fitted into an opening in the wall, valve (15) is pushed onto the grommet and thus lightly held, until tube (13) is inserted into the grommet and compresses it to grip more tightly.

Description: This invention relates to the mounting of a one-way valve in a gas meter. It is known from U.K. Patent No. 2 097 937 to mount a one-way valve in a gas-flow tube of a gas meter so as to prevent fraudulent attempts to reverse the direction of gas flow through the meter. The assembly of these meters is an awkward procedure involving putting the valve parts into a location which is difficult for access. According to the invention a method of assembling a gas meter of the kind having a gas-flow tube (13) leading to an opening (21) in a wall (12) and a one-way valve (11) located to affect flow in said gas-­ flow tube is characterized by the steps of placing a compressible grommet (22) having a waisted outer circumference into said opening (21) so that the wall (12) seats in said waist, pushing the one-way valve (11) onto the grommet (22) from one side of the wall so that an opening (16) thereof also seats in said waist and pushing one end of said gas-­ flow tube (13) into the centre opening of the grommet (22) from the other side of the wall whereby to compress the grommet (22) and cause it to increase its grip on the wall (12), the valve (11) and the tube (13). The invention also extends to a gas meter adapted for the method of assembly outlined above. A specific example of the invention is illustrated in the accompanying drawings, in which:- Figure 1 is a top view of a one-way valve, Figure 2 is a side sectional view of a top plate of the valve of Figure 1, Figure 3 is a side view part in section of the valve of Figure 1, and Figure 4 is a partly diagrammatic side view of the valve of Figures 1 to 3 in the process of being mounted in a gas meter. The valve shown is to be used in a gas meter to prevent reverse flow of gas as described in Patent No. 2097937, particularly in a similar manner to that shown in Figure 1 thereof. A one-way flap valve (11) is to be mounted in the gas meter at the conjunction of a valve chamber wall (12) and an exhaust tube (13). Normally gas flowing through the meter leaves by way of the exhaust tube which leads from a valve chamber housing the normal meter valves to an outlet boss. If the meter connections are reversed then gas may be made to flow down the exhaust tube into the valve chamber. To prevent this, one-way valve (11) closes when a reverse flow occurs. The one-way valve as seen in Figures 1 to 3 comprises a top plate (15) having a circular opening (16), and a body member (17). Body member (17) is secured to the top plate and provides an internal gas flow path connected to opening (16) and turning through 90° to an opening (18) in an angled face (19). Face (19) lies at approximately 45° to the vertical. At the top edge of the face is secured the top edge of a flexible valve flap (20) made of reinforced nitrile rubber. The flap is large enough to cover opening (18) and seats on the face (19). There may be support strips (not shown) across the opening to support the flap. Normally gas flows in the direction of arrow A and lifts the flexible flap off the seat, so as to establish a gas flow into opening (16). Because of the angle of the valve seat the flap tends to fall back to the closed position under gravity when there is no flow. Should a reverse gas flow be connected, the gas pressure will tend only to pressure the flap (20) more securely against its seat and support strips (where fitted). Thus there will be no gas flow. Referring to Figure 4 there is shown the top wall (12) of a valve chamber having an opening (21) through which gas normally flows into exhaust tube (13). A compressible rubber grommet (22) has a waisted outer circumference in which the edges of opening (21) seat. Exhaust tube (13) is a tight fit in the inner opening of grommet (22) whereby in known arrangements the tube is both held and sealed. To mount the one-way valve (11) the grommet (22) is first placed in the opening (21). The valve is then pushed onto grommet (22) so that the opening (16) is forced into the same waisted portion as opening (21) in the position shown in the drawing. In this position the valve is only lightly secured to wall (12), but sufficiently so for reasonable handling to take place. The exhaust tube (13) is then pushed down in the direction of arrow B so that it enters the grommet compressing the material of the grommet around the wall (12) and the plate (15) and thus effectively locking and sealing the valve (11) in position. It will be appreciated that by this means the valve is mounted without the need for any further components. All that is required is careful dimensioning of the grommet (22) with respect to the diameter of tube (13) so that insertion of tube (13) into the grommet compresses the grommet to cause it to grip the valve sufficiently well. The mounting of the valve is thus achieved cheaply and quickly without any difficult assembling procedures.

Claims: 1. A method of assembling a gas meter of the kind having a gas-flow tube (13) leading to an opening (21) in a wall (12)and a one-way valve (11) located to affect flow in said gas-flow tube characterized by the steps of placing a compressible grommet (22) having a waisted outer circumference into said opening (21) so that the wall (12) seats in said waist, pushing the one-way valve (11) onto the grommet (22) from one side of the wall so that an opening (16) thereof also seats in said waist and pushing one end of said gas-flow tube (13) into the centre opening of the grommet (22) from the other side of the wall whereby to compress the grommet (22) and cause it to increase its grip on the wall (12), the valve (11) and the tube (13). 2. A method as claimed in claim 1, further characterized by said step of pushing the one-way valve (11) onto the grommet (22) comprising pressing a flat top plate (15) of the valve into contact with the wall (13). 3. A gas meter of the kind having a gas-flow tube (13) leading to an opening (21) in an internal wall (12) and a one-way valve (11) located to affect flow in said gas-flow tube, characterized by being adapted for assembly by the method of claim 1 or claim 2, having the one-way valve (11) mounted on the opposite side of wall (12) from the tube (13) and connected in line with said tube. 4. A gas meter as claimed in claim 3, further characterized by the selection of the dimensions of the grommet (22), tube (13) and openings (21, 16) so that the valve (11) alone is mounted by the grommet on the wall (12) sufficiently for handling to take place, and is secured more firmly in place by compression of the grommet by the insertion of the tube (13). 5. A gas meter as claimed in claim 3or claim 4, further characterized by said one-way valve (11) having an internal gas flow path from its opening connecting with the tube (13) which path turns through an angle to terminate in an angled opening (18) and a flexible valve flap (20) which is capable of covering the angled opening. 6. A gas meter as claimed in claim 5, further characterized by said flap (20) being of nitrile rubber.

Inventors: WICHER, EUGENIUSZ
Applicants: SMITH METERS LIMITED
Application year: 1986
Main classification: G01F15
IPC codes: G01F15