FEATURE ATEX EQUIPMENT
VENTILATION IN CHEMICAL STORAGE
Ventilation of chemical storage areas is important to ensure clean air and a safe working environment. In this article, Axair Fans discusses the different requirements for chemical storage ventilation, including in ATEX applications
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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.
sunlight. Effective ventilation not only keeps chemicals appropriately cooled but also reduces this build-up of fumes. As a general rule, any ventilation system should
exhaust fume outside into the atmosphere and away from additional sources of ignition, by exhausting away this prevents surrounding rooms and people from inhaling or been affected by the harmful gases. Chemicals can be classed in two categories, flammable and corrosive. ATEX certified industrial fans are designed specifically for use within potentially hazardous or combustible environments and are manufactured with non-sparking components such as copper inlets, in other terms the flammable gases. Corrosive fumes, when in large volumes and
Flammable substances
and liquids are used in most laboratory and industrial
environments, but storage of these materials improperly can pose a great risk to personnel, the public and property. There are a large variety of chemical storage cabinets available on the market, but best practice guidelines for COSSH chemical storage units indicate that a chemical store should be well ventilated. Those available on the market include both ventilated and non-ventilated units so it is useful to understand the importance of effective chemical store ventilation. When choosing a storage unit for the
safekeeping of flammable substances, ventilation should be one of the key points to consider, and if not purchased as a ventilated unit, it is advisable to fit industrial chemical fans suitable for the purpose of ventilating the store. The need for ventilation and more specifically the type of fan that is required is determined by the hazardous nature of each chemical component. Temperature fluctuations in many chemicals can serve to increase vapour emissions and flammability so the need for ventilation becomes ever more apparent especially when a unit is situated in direct
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over long periods, will damage or destroy materials that they come into contact with. Substances containing corrosive bases such as those found in sulphuric or hydrochloric acids will erode the surface of the fan components if not manufactured in suitable material fit for purpose. The extraction of corrosive fumes should be done with chemical fans / corrosion resistant fans, polypropylene is the standard material, which can withstand the nature of the chemical gases that pass through the scroll and the impellers. In this instance the motor should be kept out of the air stream to ensure long lifespan and also to prevent the overheating of the motorised components. The duct work that is attached to the industrial fan should also carry
the same of similar level of protection against corrosion as the fan scroll and impeller itself. In smaller storage units where the materials are non-corrosive and ventilation is more general, an axial fan can be used to ventilate, this should be certified for use in ATEX applications but in these instances the motor that is held within the air stream can withstand the nature of the gases, fumes or mists. It is worth noting that flammable gases are denser than air so they can accumulate at floor level. For this reason the ventilation system should be set up to ensure that these low level potentially hazardous gases can be extracted effectively. 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 Fans
www.axair-fans.co.uk / INDUSTRIALCOMPLIANCE
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