FEATURE HVAC
THE IMPORTANCE OF CHEMICAL STORAGE VENTILATION
by Andrew Ward, product sales engineer, Axair Fans M
any industries require a number of potentially hazardous
chemicals in day-to-day maintenance, manufacturing, cleaning, sterilisation, testing and operating applications. The safe storage of these chemicals involves a number of considerations in terms of temperature, ignition control, ventilation and segregation. The ventilation of chemical storage
areas is of paramount importance to ensure clean air and a safe working factory environment. Ventilation is needed for chemicals and their containers as they have the potential to release dangerous quantities of vapours or gases that are damaging, flammable, corrosive, irritating or toxic. These vapours quickly accumulate and present a considerable hazard if left unventilated. Well ventilated storage is particularly
key for those substances classed as fuming or highly volatile. It is recommended that such ventilation be by air extraction from the storage room or cupboard to an external exhaust at a safe distance from any openings (windows or doors) back into the building.
14 NOVEMBER 2019 | IRISH MANUFACTURING The fume extraction system needs to
be suitable for handling air that is potentially corrosive, given the nature of the chemical vapours to be carried from the storage area. Axair offers a range of fans designed specifically for extracting corrosive air, due to their polypropylene construction. In addition to standard corrosive fume extraction, Axair also provide polypropylene fans suitable for ATEX Zone 2 applications. These applications will have been assessed by an official ATEX specialist and deemed to have a risk of the accidental presence of explosive fumes. In such chemical fume
extraction systems, it is best practice to site the fan at the end of the ductwork system. The reasoning behind this is to keep the ductwork under negative pressure which means, in the event of a leak, the system would draw in clean air rather than blowing out fumes into the building. This would limit any
Seat fan, pedestal and isolator
damage caused by the leak before it was identified. In order to accurately specify a fan,
there are two key pieces of information required; the airflow rate and the system resistance. Airflow rate is be based on the number of air changes per hour needed in the storage area. From the airflow rate, the size the ductwork is determined and so the system resistance is calculated. There may be a requirement to control the fan with a sensor to switch the fan on and off. This can be achieved with the use of an inverter. The sensor sends a signal to the inverter, which in turn controls the power source to the fan. Please note that if there is a
possibility the installation needs to be ATEX rated, then an expert needs to determine the Zone classification for the area. The information they provide will cover the size of the Zoned area and the standard of equipment to be used in the Zone.
Axair
www.ax-airfans.co.uk
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