GB2227687A

GB2227687A - Filter

Info

Publication number: GB2227687A
Application number: GB9001553A
Authority: GB
Inventors: Norman Frank Dewey
Original assignee: Dewey Waters & Co
Current assignee: Dewey Waters & Co
Priority date: 1989-02-06
Filing date: 1990-01-23
Publication date: 1990-08-08
Anticipated expiration: 2010-01-23
Also published as: GB9001553D0; GB8902583D0; GB2227687B

Abstract

An overflow pipe 3 from a water tank 1 includes a filter 6, designed to exclude insects and arranged at an angle across the pipe to present a total open area exceeding the pipe cross-section. The filter is mounted by cutting the pipe and welding the filter between the two halves. <IMAGE>

Description

FILTER The present invention relates to a filter for use in a pipe. It is particularly, but not exclusively, concerned with the case where that pipe is an overflow from a water tank.

Most water tanks have an overflow pipe to permit excess water to escape from the tank. Recent legislation has required that the pipe contain a filter in the form of a mesh for preventing insects climbing the overflow pipe and hence getting into the tank. It is therefore standard that a filter is placed extending generally radially within the pipe.

However, the filter acts as a constriction on the flow through the pipe, which is undesirable.

Furthermore, there may be floating material in the tank which passes down the overflow pipe, and this collects on the filter and, with current designs, rapidly blocks it.

To reduce these problems, it is known to provide a section of the pipe which has a greater diameter than the rest of the pipe, and to position the filter across that large-diameter section. However, this has the disadvantage that the large-diameter section must be made specially, increasing the cost of the overflow pipe.

Therefore, the present invention proposes that the filter be placed in a pipe inclined at an angle relative to the diameter of the pipe. Preferably, the angle of inclination is such that the total open area of the filter (i.e. the area of the holes in the filter) is at least as great as the transverse cross-sectional area of the hollow interior of the pipe. In this way. the effective cross-sectional area at the filter is not reduced, so that water can flow freely through the pipe.

Furthermore, use of an inclined filter has the advantage that floating material which has been carried down the pipe will be washed to the downstream edge of the filter, thereby leaving the remainder of the filter free. This is particularly true if the pipe containing the filter is vertical, but the advantage can also be achieved on horizontal pipes, particularly when the leading edge of the filter is uppermost.

An embodiment of the invention will now be described in detail, by way of example, with reference to the accompanying drawings, in which: Fig. 1 shows a cross-sectional view of a tank and an overflow pipe incorporating the present invention; and Fig. 2 shows a detail of a section of the pipe incorporating the filter.

Referring first to Fig. 1, a tank 1 for liquid 2 has an overflow pipe 3 extending therefrom. The overflow pipe 3 has a pipe section 4 therein, secured to the rest of the pipe 3 by flanges 5. Within that pipe section, a filter 6 is located, which filter 6 is inclined relative to the diameter of the pipe.

The angle of inclination of the filter to the pipe depends on the pore size of the filter. It is proposed that this angle be such that the area defined by the pores (the "open" area of the filter) is at least as great as the cross-sectional area of the pipe. Thus, the filter does not provide a restriction to the pipe area.

The angle of inclination of the filter 6 may then be selected in dependence on its pore size, but, for example, an inclination angle of 65", relative to the diameter of the pipe, has been found entirely satisfactory for a pore size of 0.65 mm.

Fig. 2 shows in more detail the construction of the pipe section 4. That pipe section 4 comprises two parts, 4a,4b which are formed by cutting the pipe section 4 at a suitable inclined angle. The filter 6 is then stuck to one of the pipe sections (e.g. section 4a) and then the other section 4b is stuck to the filter 6. The join is sealed by a weld 7.

Consider now the arrangement of Fig. 1, and suppose that there is floating material on the water 2 in the tank 1. When there is an overflow, the floating material is carried down the overflow pipe 3 and comes to rest on the filter 6. If the filter 6 extended across the diameter of the pipe, it would rapidly become blocked.

However, the use of an inclined filter according to the present invention causes any floating material trapped by the filter 6 to be washed to the leading (downstream) edge of the filter and the floating material collects at that edge, leaving the remainder of the filter 6 free.

This advantage also occurs in a horizontal pipe, such as that shown in Fig. 2, particularly when the leading edge 8 is uppermost (i.e. if the flow is from right to left in Fig. 2), since floating material in the pipe will collect at that upper edge 8.

As was mentioned earlier, the pipe section 4 is provided with flanges 5 receiving e.g. bolts to secure the pipe section 4 to the rest of the pipe 3. This means that, should the filter become clogged, it is relatively easy to remove the pipe section 4 and clean it by causing water to flow through it in the opposite direction to the normal flow, and then replace it in the overflow pipe 3.

Although the present invention has been described with reference to an overflow pipe, it is not limited thereto and can be used in any arrangement in which a filter is needed in a pipe.

Claims

1. A pipe having a filter extending across the interior of the pipe, the filter being located in the pipe at angle inclined relative to the transverse diameter of the pipe.

2. A pipe according to claim 1 wherein the total open area of the filter is at least as great as the transverse cross-sectional area of the interior of the pipe.

3. A pipe, having a filter substantially as herein described with reference to the accompanying drawings.

4. A pipe system for passing liquid in a predetermined direction, the system containing a pipe according to any one of the preceding claims, wherein the part of the filter which is in uppermost is downstream in said predetermined direction relative to the rest of the filter.

5. A method of making a pipe comprising mounting a filter in the pipe so that the filter extends across the interior of the pipe, the filter being located in the pipe at angle inclined relative to the transverse diameter of the pipe.

6. A method of mounting a filter in a pipe comprising cutting a pipe section at an inclined angle thereby forming two portions adhering the filter to the inclined end of one of the portions, adhering the inclined end of the other portion to the filter, and sealing the interface between the two portions.