What is BS EN 13141-9 - Externally mounted humidity controlled air transfer device about? 
BS EN 13141 is a European Standard that discusses the performance testing of components/products for residential ventilation.
BS EN 13141-9 is the ninth part of the series that primarily focuses on testing performance of externally mounted humidity-controlled air transfer devices.
BS EN 13141-9 specifies laboratory methods for testing humidity-controlled air inlets operating under pressure differences.
Note: BS EN 13141-9 does not apply to the evaluation of air filtration, condensation risk and noise production.
Who is BS EN 13141-9 - Externally mounted humidity controlled air transfer device for? 
BS EN 13141-9 on externally mounted humidity controlled air transfer device is relevant to: 
- Ventilation and air-conditioning system manufacturers and designers
- Ventilation product/component manufacturers and designers
- Quality control and testing personnel
- Architects and contractors
- Residential building developers and planners
Why should you use BS EN 13141-9- Externally mounted humidity controlled air transfer device?
Indoor air is kept clean and fresh with proper ventilation systems, that ensure that fresh air enters and bad air exits, such that moisture, smells, gases, dust, and other contaminants are removed. For this reason, it is essential that the exhaust ventilation system be tested for optimal performance and effectiveness, to make living spaces comfortable for its inhabitants.
BS EN 13141-9 provides a test which is useful for measuring several volume flow rates induced through a device controlled by humidity conditions, under an applied static pressure difference, to define the flow rate/humidity characteristic curve.
If you are a manufacturer, BS EN 13141-9-compliant performance testing on externally mounted humidity-controlled air transfer device, can help determine whether your products are fit for purpose and ensure that they play a positive role in the performance of the overall ventilation systems.
