Giving foul air the red card

Wavin Plastics has developed valves that help prevent the release of foul air into buildings. The valves ventilate drainage systems and prevent the loss of water seals in traps.

The issue of indoor air quality is high on the agenda. The government has become increasingly concerned with the large number of health problems connected with indoor pollution, which are thought to affect much of the population.

The campaign to limit indoor air pollution is not just limited to the UK. The World Health Organisation has listed the issue as one of the leading environmental health problems it has to tackle, and European governments included the it in their Declaration on Action for Environment and Health in the European Union.

The potential effects of indoor air pollution include unpleasant smells, sensitisation and asthmatic reactions related to biological aerosols in the indoor air and the fatal consequences of exposure to pathogenic organisms or chemicals.

UK guidelines
In the UK, the Department of Health Committee on Medical Effects of Air Pollutants
has released guidelines for manufacturers, architects and engineers involved with building design and services, to assist in the process of reducing foul air.

Growing concern over indoor air quality is also being driven by the new Part L and Part F building regulations. The new regulations will ensure that buildings become much more airtight, forcing designers to consider ventilation rates more carefully.

High on most organisations list of priorities for dealing with indoor air quality is the issue of drains and sanitary pipes. A key issue in preventing the release of foul air into a building from drains or sanitary pipes is the potential for the failure of water seals in traps.

As a result, Wavin Plastics developed the OsmaVent 110 and OsmaVent 40 Air Admittance valves, designed for use within buildings with above-ground drainage systems in accordance with the Building Regulations 1985.

Wavin's range of BBA-certified OsmaVent Air Admittance Valves have a ten-year guarantee, and touted as creating "a new benchmark for versatility, reliability and performance". And the valves meet and exceed the minimum airflow requirements for AAVs as defined by BS EN 12056-2 and have achieved the maximum A1 rating.

The valves provide a means of ventilation to the drainage system and prevent the loss of water seals in traps and consequent release of foul air into the building. The system can be used on branch discharge pipes and on discharge stacks serving up to ten storeys.

The valves admits air under conditions of reduced pressure in the discharge pipes and prevents water seals in the traps from being drawn therefore contributing to the ventilation of the main drain into which the discharge stack incorporating the valve is connected.

The equalisation of the pressure within the system is achieved without the escape of foul air as the valve only admits air and closes against a seal as soon as pressure equalisation occurs.

The OsmaVent system can be used in a wide variety of applications including domestic buildings, such as bungalows, houses, multi-storey flats and halls of residence at universities. The valves are also suitable for non-domestic buildings, such as offices, factories, schools and public buildings, where foul air is a potential issue.

The valves admit sufficient quantities of air into the stack when they are subjected to a reduced pressure and thereby prevent loss of the water seals in appliance traps.

Under conditions of increased pressure in the drainage system, each valve will remain closed thereby preventing the release of foul air into the building.

Furthermore, a pressure increase sufficient to raise the level in the water seal or to cause foul air to bubble up through the seal is an indication that a drain blockage has occurred or that the system is being overloaded or otherwise misused.

Crucially, the OsmaVent system allows access to sanitary pipe work, which is particularly useful for clearing blockages, critical when truing to reduce foul air incidences.

Also, OsmaVent 110 valves reduce the requirement for vent piping and eliminate the need for costly roof penetrations. They can be installed in a loft, duct or room - providing exceptional flexibility for stack layout.

AAVs should be installed in locations that are accessible and permit free movement of air to the valve. When installing in a loft the OsmaVent 110 should be situated at least 150mm above any insulation and the upper half of the insulation packaging should be retained in order to protect the unit from freezing. This facilitates the ability to achieve the operating temperature range from -20ÚC to 60ÚC.

For installations within a duct or room, the OsmaVent 110 should be installed above the flood level of the highest appliance.

Easy fit
OsmaVent valves are made using ABS - a material conventional in drainage systems. The all-plastic construction means that it cannot rust or corrode, and the slimline profile allows an easy fit into pipe ducts.

Additional innovative design features include an integral insect screen that prevents the ingress of insects or vermin, a push-fit connector that removes the requirement for solvent welding and the polystyrene cap as part of the packaging to prevent the valve freezing.

Furthermore, repeated opening and closing will not adversely affect the sealing or operation of the valve, and the valve will have a life expectancy equivalent to that of the drainage system in which it is installed.

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