The Only Line of Defence

Why the quality of AAVs must be high

The water trap seal is the only barrier between the drainage system and the living and/or Quality Air Admittance Valvesworking space; it is therefore essential that this is maintained at all times. The loss of a trap seal results in unwanted smells, noise and, importantly, the risk of pathogens spreading from the drainage system into the inhabited space. Whilst these are unpleasant in a domestic environment, there are serious health and safety concerns in a commercial environment, where the building owners and/or occupiers have a duty of care.

An Air Admittance Valve (AAV) is a thin but very effectual line of defence. It balances pressure in the drainage system, opening to allow fresh air in but sealing tight to keep nasties in their place.

Critical aspects of an AAV’s operation are:
• The need to respond quickly to changes in pressure, every time.
• The necessity to seal completely tight with no leakage whatsoever.
• Longevity of operation; as long as the drainage system itself.

Various standards exist across the world to “police” the performance and installation of AAVs. However, the implementation of these standards varies widely, with some countries having no relevant standards or approvals. Studor has been instrumental in working with various standards bodies, worldwide.

There is such a risk from the drainage system that there really should be standards in place to ensure that poor quality AAVs cannot be installed. With events such as the tragic SARS outbreak in the Amoy Gardens complex in Hong Kong, where it was proven that defective water trap seals had been a major contributor to the spread of disease, comes an increasing awareness and knowledge of the ever-increasing risks from drainage systems.

Quality Air Admittance ValvesUnfortunately, there are many poor quality AAVs produced around the world and a number of these have severely damaged the reputation of AAVs in many countries, often where standards did not exist, or false claims of compliance were made. All Studor AAVs are manufactured to the highest standards and because of our commitment to quality manufacture, all Studor products carry a “lifetime of system” warranty, which guarantees that all products will be defect free. It is our ethos to strive to exceed the statutory minimum requirements, not merely comply with them.

In Europe, EN12380 requires a “System 4” assessment of conformity, which means that no independent involvement is required to comply with the standard. However, unlike many other AAV manufacturers, rather than just relying on the CE mark, and the basic requirements to comply with this standard, and Studor has gone the extra mile to obtain KEYMARK approval.


The KEYMARK is a European quality mark and product certification scheme issued by Quality Air Admittance Valvesthe European Standard Organisation CEN (similar to the Kitemark issued in the UK by the BSI) and empowered by DIN CERTCO – the certification organisation of DIN, the German Institute for Standardisation. It proves that the Studor products fully comply with EN 12380:2002 through DIN CERTCO’s independent auditing and further reinforces the emphasis Studor places on quality.

In accordance with the KEYMARK regulations, Studor’s factories receive annual unannounced audits by NSF International and our products are tested by BRE, an independent testing institute, every two years.

Quality Air Admittance ValvesDuring the production process, every Studor valve is tested twice. In addition, a percentage from each production batch is randomly selected and submitted from the factories to our head office for additional in-house testing by our dedicated Product Engineer.

Studor products are developed not only to comply with international standards, but in many cases to exceed them. One example of this is in relation to the opening pressure of Studor AAVs. Each valve incorporates a Studor patented diaphragm. The quality of an AAV is determined by the material used for the diaphragm, as they need to be precisely engineered to prevent short-term failure. Very tight tolerances are required. Whilst EN12380 requires an opening pressure between 0 Pa and -150 Pa, the Studor AAVs open at -70 Pa, well within the specified limit.

A further example is in relation to the Maxi-Vent AAV. This is rated AI in accordance Quality Air Admittance Valveswith EN12380, which means that it can be installed below the flood level of the appliance to which it is connected and can be installed in extreme temperatures (from -20°C to +60°C). However, Studor guarantees that the Maxi-Vent will operate correctly, with no loss of function whatsoever, at a temperature of -40°C; ideal for areas such as Scandinavia, where the Maxi-Vent AAV can be installed in non-thermally insulated areas.

In the USA, standards ASSE1050 and ASSE1051 include high and low temperature endurance tests, which includes the valves being subjected to -40°F (-40°C) for eight hours before being returned to a laboratory controlled temperature of 73.4°F ± 3.6°F (23.0°C ± 2.0°C) and then being pressure tested. This is a material test, to ensure that the valves will continue to function if the material is exposed to low air temperatures. The same standards include endurance tests of 500,000 cycles in total, which is an aspect not considered within the European EN12380, as yet.

Quality Air Admittance ValvesBy contrast, the testing carried out to exceed the requirements of EN12380 is a functional test, with the testing being carried out whilst the valves are maintained at -40°C (-40°F), ensuring that the valves will operate correctly when they are installed in locations which may drop to this temperature. To the best of our knowledge, there is no one else in the market that is prepared to offer this extensive operating temperature range.

In addition to external installations, as the Maxi-Vent is often installed in roof spaces and voids where temperature can drop significantly (especially as the building insulation is often below the position of the Maxi-Vent), this adds to the product’s versatility. Even in climates where significant low temperatures are not an issue, the performance of the Maxi-Vent in exceeding this standard further confirms the quality of the product and the durability of the diaphragm. This guarantee is supported by an independent test report from BRE, which verifies that the Studor Maxi-Vent fully functions at -40°C.
For further information please refer to www.studor .net.

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