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RR288 - Development of a ventilator test procedure to take account of external wind conditions

This project investigates the viability of enhancing an existing ventilator test procedure, to account for the presence of a wind across the face of a ventilator.

Test results show considerable variation between vent performance when subjected to crosswind flows across a range of face angles. Many designs exhibited strong variation with face angle, while some exhibited significant effective area reductions when the crosswind was introduced.

The present findings indicate that the maximum bulk wind speed required for an assessment of vent performance is 21 ms-1. Modelling suggests that a vent crossflow speed of up to 31.5 ms-1 be used for the future test procedure.

Measurements should be taken at five face angles of -90°, -45°, 0°, 45° and 90°. However, this should be modified to include additional measurements at face angles 135°,180° and - 135° for asymmetrical cowls.

Some further work should be carried out, in partnership with vent manufacturers, to establish a defined measurement point for the differential pressure in each given ventilator unit.

In conclusion, the test procedure described here should form the basis for the characterisation of vent units with cowls that are currently available, and those that seek British Standards approval in the future.

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Updated 2009-05-05