GB2228689A

GB2228689A - Screen unit

Info

Publication number: GB2228689A
Application number: GB8915955A
Authority: GB
Inventors: Norman John Taylor
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-03-01
Filing date: 1989-07-12
Publication date: 1990-09-05
Anticipated expiration: 2009-07-12
Also published as: GB8915955D0; GB2228689B; GB8904683D0

Abstract

A screen unit designed to exclude insects from a water tank, which may be fitted either in the air vent or the overflow pipe, comprises a generally cylindrical housing provided with an inlet (8), an outlet (10) and a removable cover (12) which enables a filter (16) to be placed therein. As shown the filter is urged on to flange (14) by a spring (18). In other constructions the inlet and outlet are axially aligned, and the cover is in the side of the housing. The filter mesh is from 0.2 to 0.8 mms. <IMAGE>

Description

PATENTS ACT 1977 WL/BMCjA 5700 G8 Title: "Improvements relating to tanks" Description of Invention This invention is concerned with improvements relating to tanks, particularly venting or overflow units for tanks.

The invention will be described herein in relation to water tanks, for which the invention has primarily been devised. It is however to be appreciated that the invention may be utilised in tanks other than those intended for water storage.

Water storage tanks must conventionally be open to the atmosphere, either by way of an overflow pipe or by way of an inlet to allow flow of asr into the tanK when water is being drained, or bcth. Particularly where tanks are used to contain water for domestic or personal use, it is ob#ectionabie that insects may enter the tank.

Screen units are known, which may be located across an overflow duct to prevent entry of insects into the tank. However such units as are at present available are difficult to clean. This difficulty tends to result in a reduction in the frequency with which the units are cleaned, which may produce health hazards, but additionally in due course blocks the unit so that the flow rate through the unit is lowered to an unacceptable level.

According to this invention there is provided a screen unit for a tank compr:sing a housing, an inlet extending into the housing, an outlet extending from the housing, and a filter member removably mounted in the housing so as to extend across the housing between the inlet and the outlet.

Preferably the filter member extends substantially completely across the housing, e.g. being located on a flange within the housing, being operative thereby to prevent passage of insects between the inlet and the outlet.

Advantageously the housing comprises a separable cover member, of a size such that, when removed, the filter member may be separated from the housing, conveniently in a manner which does not necessitate movement of the inlet andfor outlet. Thus, where the device is connected at one or both of the inlet and outlet, by removal of the cover member the filter member may be withdrawn and replaced without disturbance to the inlet and/or outlet connections.

Advantageously the filter member is urged (e.g.) by a spring into an operative position, such as against a seating provided by a flange within the housing, conveniently the spring co-acting against the cover member such that when the cover member is removed, the spring, and hence the filter member may be removed from the housing. Alternatively the housing may be provided with a formation (such as a tongue or groove formation) with which a cooperative formation on the filter member (such as a groove or tongue formation: may engage to permit (when the cover member is removed; the filter member to be withdrawn from and replaced into the housing.

Preferably the filter member is in the form of a basket, in which dead insects and other extraneous material may be collected, and removed by lif ins the filter member from the housing and emptying and cleaning.

In this manner tue filter member may be removed from the screen unit for emptying and cleaning easIly and quick#y.

Preferably the housing is generally cylindrical, and the filter member is also generally cylindrical.

The filter member preferably comprises a fine mesh, i.e. a mesh which is sufficiently fine to keep out those insects which it is desired to exclude.

ane of course the mesh size will be dependent upon the required performance.

Thus the holes will not be so small so as to prevent a significant obstruction to flow of water therethrough, nor so large as to permit insects of the kind desired to be excluded from passing therethrough. It is preferred that the holes be in the range 0.1 to 1.0 mm, preferably 0.2 to 0.8 mm; for example a screen of 30 mesh, comprising holes of 0.57 mm may conveniently be used.

In addition desirably the spacing of the holes of the filter member is such as not unduly to impede flow therethough, and desirably the ratio of surface area to hole area is between 60:40 and 40:60, e.g. about 55:45.

Advantageously the construction and arrangement is such that the cross-sectional area of the housing which is available for flow of water from the inlet to the outlet, and the surface area presented by the filter member to the flow of water between the inlet and the outlet, is significantly greater than the cross-sectional area of the pipe through which water is admitted to the housing, preferably being greater by a factor of at least 2, preferably at least 2.5 where the ratio above is 60:40. In this manner, the housing and filter member present no significant obstacle to flow of water though the screeen unit.

There will now be given a detailed description, to be read with reference to the accompanying drawings, of three screen units which are preferred embodiments of this invention, having been selected for the purposes of illustrating the invention by way of example.

In the accompanying drawings: FIGURE 1 is a perspective view of the first embodiment; FIGURE 2 is a vertical sectional view of the first embodiment; FIGURE 3 is a schematic view illustrating the first embodiment in use; FIGURE 4 is a perspective view of the second embodiment; FiGURE 5 is a vertical sectional view of the second embodiment; FIGURE 6 is a perspective view of the third embodiment with a cover member thereof removed; and FIGURE 7 is a vertical sectional view of the third embodiment.

The screen unit which is the first embodiment of this invention is specifically for use with a coid waver tank T, and may be used either as an air vent, or as an overflow unit, or both.

The unit comprises a generally cylindrical housing 6 provided with a generally radially-extending inlet pipe 8 and an axially-extending outlet pipe 10 extending through a base 7 of the housing.

The top of the housing is open, and is closed by a removable cover 12 which may be screw-threaded with the housing, or press-fit thereon, conveniently a sealing gasket 13 being utilised.

Internally of the housing 6, a short distance below the inlet 8, there is provided a circular flange 14 on which a filter unit 16 is located, the filter unit being generally cylindrical, of an outside diameter slightly smaller than the inside diameter of the housing 6, and being provided with an annular lip 15 which may be located on the flange 14.

The filter unit 16 is of a fine mesh, having holes between 0.1 and 1.0 mm, conveniently being of 30 mesh, and having a ratio of surface to hole area of about 55:45.

Extending between the cover 12 and the rim 15, being effective to urge the filter unit 16 against the flange 14, is a compression spring 18.

Figure 3 illustrates two positions of location for the screen unit, in relation to a water tank T. In position A, in which the unit is used as a screen unit for an air inlet, the pipe 10 being connected to the tank, and the pipe 8 being open to the atmosphere. Any insects which crawl through the pipe 8 will be prevented from gaining access to the tank by the filter unit 16. On the ocassion that the filter unit 16 needs to be cleaned, the cover 12 may be removed from the housing 6, allowing the spring 18 to be lifted out, and the mesh basket 16 removed from the housing, emptied, and cleaned before replacing within the housing, and relocating the spring and cover in position.

In the position B the pipe 8 is connected to the tank at an overflow position, the pipe 10 being connected to a waste outlet, water flowing downwardly through the housing 6 under overflow conditions. Similarly.

insects passing upwardly through the pipe 10 will be prevented from entering the tank by the filter member 16.

As is apparent from Figure 2, the cross-sectional area of the housing is significantly greater than the cross-sectional area of the pipe 8 through which water is admitted to the housing, such that the filter member 16 presents no significantly greater resistance by virtue of the cross-sectional area thereof, to flow of water between the inlet and the outlet.

Of course as an alternative to cleaning the filter unit 16, on maintenance of the screen unit a new filter member may be utilised.

The second embodiment of the invention is similar to that above described, and will be described with reference to Figures 4 and 5 of the accompanying drawings, in which similar numerals, with the suffix a, have been utilised to indicate parts corresponding to those of the first embodiment.

Whilst in the first embodiment the pipe 8 is set at right angles to the pipe 10, with the cover 12 in line with the pipe 10 to permit removal of the filter unit 16, in the second embodiment the pipes 8a and 10a are in alignment, an opening being provided in the side of the housing 6a, to provide access to the interior of the housing, for removal of the filter until 16a, said opening being provided with a removable cover 12a.

In addition, in place of the compression spring 18 used in the first embodiment, in the second embodiment the filter until 16a is retained in position by a spring circlip 21, or similar device.

The third embodiment of the invention is similar to that above described, and will be described with reference to Figures 5 and 6 of the accompanying drawings, in which similar numerals, with the suffix b, have been utilised to indicate parts corresponding to those of the first embodiment.

In the third embodiment, the inlet pipe 8b is axially in line with the outlet pipe 10b, the cylindrical housing 6b extending between said inlet and outlet, generally at an axis extending at right angles to the common axis of the inlet and outlet.

Provided at diametrically opposite opositions on the interior of the housing 6b are groove formations 20, with which cooperative tongue formations on the sides of the filter member 16b may be engaged, permitting the filter member to be slid into and out of position between the inlet and the outlet. Subsequently a cover member 12b may be secured over the opening of the housing.

The diameter of the housing 6b is greater than the diameters of the inlet and outlet pipes, such that the surface area presented by the filter member to the flow of water between the inlet and the outlet is significantly greater than the cross-sectional area of the pipe through which water is admitted to the housing, conveniently being approximately 2.5 times said cross-sectional area.

It is to be appreciated that in the above embodiments, access to the filter until is convenient, and may be accomplished without taking the filter device itself out of line, and without disturbance to the inlet and the or outlet pipe.

The features disclosed in the foregoing description, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, or a class or group of substances or compositions, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS:

1. A screen unit for a tank comprising a housing, an inlet extending into the housing, an outlet extending from the housing, and a filter member removably mounted in the housing so as to extend across the housing between the inlet and the outlet.

2. A screen unit according to Claim 1 wherein the filter member extends substantially completely across the housing.

3. A screen unit according to one of Claims 1 and 2 wherein the hcusing comprises a separable cover member of a size such that, when removed, the filter member may be separated from the housing.

4. A screen unit according to any one of the preceding claims wherein the filter member is urged into an operative position.

5. A screen unit according to any one of Claims 1 to 3 wherein the housing is provided with a formation with which a cooperative formation on the filter member may be engaged.

6. A screen unit according to any one of the preceding claims within the filter member is in the form of a basket.

7. A screen unit according to any one of the preceding claims wherein the housing is generally cylindrical.

8. A screen unit according to any one of the preceding claims wherein the filter member comprises fine mesh.

9. A screen unit according to Claim 8 wherein the mesh comprises holes in the range 0.1 to 1.0 mm.

10. A screen unit according to Claim 9 wherein said range is between 0.2 and 0.8 mm.

11. A screen unit according to any one of the preceding claims wherein the spacing of the holes of the filter member is such as not unduly to impede flow therethough.

12. A screen unit according to Claim 11 wherein the ratio of surface area to hole area is between 60:40 and 40:60.

13. A screen unit according to any one of the preceding claims wherein the construction and arrangement is such that the cross-sectional area of the housing is significantly greater than the cross-sectional area of the pipe through which water is admitted to the housing.

14. A screen unit according to Claim 13 wherein the surface area presented by the filter member to flow of water is greater than the cross-sectional area of the pipe through which water is admitted to the housing by a factor of at least 2.

15. A screen unit according to Claim 14 wherein said factor is at least 2.5 when the ratio of surface area to hole area is 60:40.

16. In combination, a water tank having secured to an overflow duct thereof a screen unit according to any one of the preceding claims.

17. A screen unit constructed and arranged substantially as hereinbefore described with reference: (a) to Figures 1 to 3; (b) to Figures 4 and 5; or (c) ztv Figures 6 and 7 of the accompanying drawings.

18. Any novel feature or novel combination of features as hereinbefore described and/or as shown in the accompanying drawings.