GB2023748A

GB2023748A - Liquid flow meter

Info

Publication number: GB2023748A
Application number: GB7920805A
Authority: GB
Original assignee: Valmet Oy
Current assignee: Valmet Oy
Priority date: 1978-06-22
Filing date: 1979-06-14
Publication date: 1980-01-03
Also published as: NO792005L; FR2429416A1; BR7903921A; FI57180B; GB2023748B; FI57180C; AR217521A1; DE2923628A1; SE7905473L; DK262079A

Abstract

The meter comprises a housing 11 including two substantially cup- shaped parts 21 and 22, the inner part 22 being located, with a press fit into a seating at the bottom, inside the outer part 21, which has an entry 12 and exit 13 for liquid. Partly inside the inner part 22 is a measuring mechanism 14 with its jet cup 15, rotor 16 and strainer 17. A cover part 18 and a dial cover are located and sealed by means of a bayonet lock ring 19 and O-ring 20. The entry 12 leads into an entry aperture 25 in the part 21 accommodating a neck 28 on the part 22 with an entry passage 27 and an O-ring 23 to prevent leakage. Liquid leaves the mechanism 14 through one or more outlets, then passes through an exit passage 24 formed by a space between the walls of the parts 21 and 22 to reach an aperture 26 open to the exit 13. <IMAGE>

Description

SPECIFICATION A liquid flow meter This invention relates to a liquid flow meter comprising a housing part, a measuring mechanism, within the housing part, an entry connector for conducting liquid into the flow meter, and an exit connector for conducting the liquid out of the flow meter.

Flow meters of this type, which are commonly used as so-called water meters, have very long been substantially unchanged as to their structural designs. Especially in the case of small water meters, the housing has usually been made of a copper alloy by a casting or hot die pressing procedure. It has lately become necessary to improve the corrosion resistance of the copper alloys considerably by the aid of various additives and by increasing the proportion of copper in the alloy. Particularly in the case of water meters employed in the water and sewer systems of housing estates, good resistance against chemical attack is required, and it has then also been necessary to make the water meters of a material which resists zinc depletion.

Increasing the proportion of copper in the copper alloy materials used for water meters makes machining more difficult, and the material appropriate for water meter housings has become increasingly costly as the world market price of copper rises.

Attempts have been made to eliminate such disadvantages by making the water meter housings or bodies of moulded thermoplastic material. By using suitable plastics materials, better resistance to corrosion is achieved, while the manufacturing costs are reduced at the same time. But the water meter housings of plastics materials have not been generally accepted in use, in the first place owing to the hygroscopic qualities of plastics materials and to their low creeping strength. One more serious impediment to the use of plastics materials is the fact that the strength of plastics materials declines markedly as a function of time and with increasing temperature. The chemical resistance of some plastics materials against the compulsory additives in service water is often not good enough.

The invention is intended to provide an improved flow meter having a housing component which can be resistant to corrosion by warm and cold service water, durable and reliable, suitable to be made so that its manufacturing costs are favourable, and well adapted for large series manufacturing.

According to the invention there is provided a liquid flow meter comprising a housing part, a measuring mechanism within the housing part, an entry connector for conducting liquid into the flow meter, and an exit connector for conducting the liquid out of the flow meter, characterized in that the housing part of the flow meter comprises two cup-shaped parts with different diameters placed one in the other and mutually connected so that a space remaining between the walls of the said cupshaped parts constitutes a flow passage for the liquid entering or leaving the measuring mechanism, and that for the incoming liquid to flow into or out of the measuring mechanism the inner cup-shaped part is provided with an aperture which communicates with an aperture in the outer part for the entry or exit connector.

Various advantages which may be gained by suitable designs and techniques and with the aid of the invention include the following among others: -The manufacturing of the housing component of the flow meter may be accomplished by a shaping process, that is by deep drawing from suitable sheet material.

-The cost of the housing component can be considerably lower than that of a housing component made by casting or hot die pressing.

-The overall size of the housing component of the flow meter can be made smaller and the wall thickness small, whereby the housing component has a light weight and the materials are economically used.

-The materials to be used are selectable in a wide range in view of corrosion resistance.

-The same tools are usable for making housing components of various alloys or materials.

-The manufacturing can be extensively automated, thereby achieving not only economy but also good dimensional accuracy.

-The housing can have smooth surfaces so that impurities do not become adherent to them; the good dimensional accuracy is long maintained, and the risk of cavitation decreases.

How the invention may be put into practice is described in more detail with reference to an advantageous embodiment of the invention illustrated in the accompanying diagrammatic drawings, wherein Figure 1 shows a flow meter according to the invention in top view, and Figure 2 is a sectional view of the flow meter of Fig. 1.

The illustrated flow meter 10 comprises a housing part 11, an entry connector 1 2 for conducting liquid into the flow meter 10, and an exit connector 1 3 for conducting the liquid out of the flow meter 10. Within the housing part 11 is a measuring mechanism 14, which can be any suitable known measuring mechanism. Among other things, the measuring mechanism 14 includes a jet cup 1 5 and an impeller 16.

The housing part 11 consists of two different sized cup-shaped parts 21 and 22, which have been placed one in the other. The outer cup-shaped part 21 has apertures 25 and 26 for the entry connector 1 2 and the exit con nector 1 3 respectively. The inner cup-shaped part 22 has an aperture 27 coinciding with the aperture 25 in the outer cup-shaped part 21.

The flow meter 10 further comprises a pressure-tight cover part 1 8 attached by a socalled bayonet lock with a fixing ring 1 9 to the outer cup-shaped part 21. It is advantageous, with a view to ensuring tight sealing in the attachment of the cover part 18, to use an O-ring packing 20. The bayonet attachment provides for rapid, convenient and positive locking of the pressure-tight cover part 1 8.

The inner cup-shaped part 22 is advantageously attached at the bottom to the outer cupshaped part 21 by press fit. The space between the walls of the cup-shaped parts 21 and 22 serves as exit passage 24 for the liquid leaving the measuring mechanism 14.

The upper edge surface of the inner cupshaped part 22 forms a mounting plane for the measuring mechanism 14, and also forms a sealing face. The aperture 27 in the inner cup-shaped part 22 is advantageously bounded by an outwardly projecting neck 28, around which is an O-ring 23 or an equivalent packing so that the entering liquid cannot bypass the measuring mechanism 1 4. A strainer 1 7 is disposed within the inner cup-shaped part 22.

The cup-shaped parts 21 and 22 of the housing part 11 of the flow meter 10 may be produced by a shaping working process, that is, by deep drawing from sheet metal alloy or other material fitting the purpose. Applicable sheet materials are, for instance, stainless and acid-proof steel, or in certain applications copper or aluminium alloy materials provided with appropriate protective coatings with a view to the conditions of corrosion. The surfaces of the cup-shaped parts 21 and 22 made from sheet material by deep drawing are substantially smoother than the inner surfaces of the housing components of prior art made by a casting process. The smooth surfaces introduce the advantage that impurities carried along by the liquid will not stick to the inner surfaces of the flow meter, and thereby a good accuracy of measurement is maintained.

As a result of the smooth surfaces, the risk of cavitation is also less than in cast housing structures.

The housing part 11 also enables the entry and exit connectors 1 2 and 1 3 to be made separately of a suitable bar material on automatic machines, and they can be fixed to the outer cup-shaped part 21 e.g. by welding, soldering, riveting, or rolling. In that case these connector ends, or the entry and exit connectors 1 2 and 13, are provided with screw-threads, whereby the flow meter 10 is installable in a pipe line with the aid of appropriate connecting members, rapidly and in a simple manner.

Adequate protection against corrosion is easily accomplished because the housing part 11 separates into separate components in those parts which are in contact with the water or other liquid to be metered. In this respect for instance the inner cup-shaped part 21 may also be a pressed plastic product with highly favourable manufacturing costs.

It is obvious that numerous modifications are conceivable within the scope of the Claims, for example the two cup-shaped parts 21 and 22 may be secured together by synthetic plastics adhesive or other bonding techniques, and with a suitable measuring mechanism the meter can be arranged for liquid to enter by the connector 1 3 and leave by the connector 12.

Claims

1. A liquid flow meter (10) comprising a housing part (11), a measuring mechanism (14) within the housing part (11), an entry connector (12) for conducting liquid into the flow meter (10) and an exit connector (13) for conducting the liquid out of the flow meter (10), characterized in that the housing part (11) of the flow meter (10) comprises two cup-shaped parts (21, 22) with different diameters placed one in the other and mutually connected so that a space remaining between the walls of the said cup-shaped parts (21, 22) constitutes a flow passage (24) for the liquid entering or leaving the measuring mechanism (14), and that for the incoming liquid to flow into or out of the measuring mechanism (14) the inner cup-shaped part (22) is provided with an aperture (27) which communicates with an aperture (25) in the outer part (21) for the entry or exit connector (12).

2. A meter according to Claim 1, wherein the cup-shaped parts (21, 22) are attached to each other by press fit.

3. A meter according to Claim 1 or 2, wherein a top edge surface of the inner cupshaped part (22) acts as a mounting plane for the measuring mechanism (14) and as a sealing face.

4. A meter according to Claim 1, 2, or 3, wherein the aperture (27) in the inner cupshaped part (22) is provided with an outwardly projecting neck (28), around which is a packing ring (23).

5. A meter according to any one of Claims 1 to 4, wherein within the inner cup-shaped part (22) is a strainer (17).

6. A meter according to any one of Claims 1 to 5, wherein a cover part (18) is attached to the outer cup-shaped part (21) by means of a "bayonet" or other fixing ring (19).

7. A meter according to any one of Claims 1 to 6, wherein the said entry connector (12) and exit connector (13) are provided with screw-threads.

8. A liquid flow meter constructed and arranged substantially as described with refer ence to and as illustrated in the accompanying drawings.