GB2306179A

GB2306179A - Air vent valve

Info

Publication number: GB2306179A
Application number: GB9520781A
Authority: GB
Inventors: Gregory John Mcdougall
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-10-11
Filing date: 1995-10-11
Publication date: 1997-04-30
Also published as: GB9520781D0

Abstract

An air vent valve for a domestic mains system comprises a cap 10 with apertures 13 arranged to be closed by a flexible inverted conically shaped seal 14. Inner surfaces of the cap between the apertures 13 support the seal 14 when pressure in a drain pipe 12 is above atmospheric pressure.

Description

AIR VENT VALVES The invention relates to air vent valves: The invention relates particularly although not exclusively to air vent valves for domestic and commercial drain systems. It is a general requirement to enable good flow of soiled water or sewerage in a drain system that the system should be well-ventilated to prevent stoppages caused by vacuums. However. the systems are preferably or generally sealed locally to reduce or prevent gases or odours escaping into the atmosphere especially near living quarters. The systems are also sealed in effect by the provision of "U-bends" that are normally provided in the system adjacent each basin, bath and toilet. The U-bends remain filled with a quantity of water to seal the drain system from the atmosphere.To meet the requirement of preventing any local vacuums in the system, it is useful to have an air vent, that is a one-way air valve, associated with each U-bend say, to allow air to enter the system beyond the U-bend when required. Such air vents are known but suffer one or more of the following disadvantages. There are relatively bulky, relatively expensive, require servicing or adjustment.

It is an object of the invention to overcome or at least reduce the above disadvantages.

According to the invention there is provided an air vent valve for domestic drain system comprising an apertured circular cap arranged to sealingly fit to an air vent hole, and a flexible inverted conically shaped seal supported centrally inside the cap which is arranged to allow air to enter the system and to close off the apertures automatically to prevent air escaping from the system.

The cap is preferably integrally formed with internal surfaces that support the seal from behind when the air pressure inside the system is greater than atmospheric pressure.

The cap may be formed with an array of apertures extending around inside the cap and behind the seal.

The seal may be formed of synthetic rubber material.

The seal may be supported by a central plug that fits through the seal and into the top of the cap.

An air vent valve according to the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a sectional side view of the valve; and Figure 2 is an exploded view of valve.

Referring to the drawings, the valve comprises a circular cap 10 open at its lower end and arranged to sealing fit to an air vent hole formed by a spur 11 formed in the side of a domestic drain pipe 12. The upper end of the cap is formed with a number of apertures 13 that can be sealed off by a conical shaped seal 14. The seal 14, which is formed of synthetic rubber, is supported inside the cap by a plug 15 that fits through a small hole in the seal and into the top of the cap 10. A protective lid 16 fits over the cap and is formed with a circular ridge 17 that press fits into a cooperating groove in the top of the cap to hold the lid in position.

It will be noted that the cap 10 is formed with the apertures 13 in such a manner that internal surfaces between the apertures that support the seal 14 from behind when the pressure inside the drain pipe 12 is greater than atmospheric pressure. Thus, the seal 14 does not have to be, to any real extent, self-supporting. As such, the seal 14 can be very flexible and inherently provide a very good seal to the inside surfaces of the cap as required.

Also, the seal will very rapidly fall away, and well away, from those inside surfaces whenever the pressure inside the drain pipe 12 drops below atmosphere pressure. This has the extra advantage that any debris or dust lying on top of the seal is easily 'flushed" by in-going air directly into the drain system; the seal therefore requires no cleaning or maintenance for the whole of its normal service life.

It will also be noted in the described embodiment that the seal can collapse to provide an effective "open" area equal almost to the area of the spur 11. The total area of the apertures 13 have or can have a total or gross surface area equal to or greater than the surface area of the spur 11. Broadly stated, embodiments of the invention are restricted in air flow capacity only by the diameter of the spur and so can deliver a flow of air when required rapidly and virtually without limit or hindrance. It is a requirement for example for some sewerage systems that venting air must be delivered at at least 800 litres per minute and often at short notice due to rapid movement of traffic in some sewerage pipes. especially in high rise buildings. If the seal does not respond rapidly, water may be sucked out of any nearby U-bends. In the described air vent for example with a spur of, say, 56 mm diameter is capable of delivering well in excess of 800 litres per minute and yet the air vent itself is not bulky and has overall dimensions of only about 60 x 60 x 60 mm.

Air vents enable sewerage down pipes to be generally sealed and there is no longer any need to provide a high rising exhaust or vent pipe extending up to the top of a building. This saves considerable costs especially for high rise buildings.

Claims

1. An air vent valve for domestic drain system comprising an apertured circular cap arranged to sealingly fit to an air vent hole, and a flexible inverted conically shaped seal supported centrally inside the cap which is arranged allow air to enter the system and to close off the apertures automatically to prevent air escaping from the system.

2. An air vent valve according to claim 1, in which the cap is integrally formed with internal surfaces that support the seal from behind when the air pressure inside the system is greater than atmospheric pressure.

3. An air vent valve according to claim 1 or 2, in which the cap is formed with an array of apertures extending around inside the cap and behind the seal.

4. An air vent valve according to any one of claims 1 to 3, in which the seal is formed of synthetic rubber material.

5. An air vent valve according to any one of claims l to 4, in which the seal is supported by a central plug that fits through the seal and into the top of the cap.

6. An air vent valve substantially as herein described with reference to the accompanying drawings.