Powder coatings are powdery mixtures of substances, mainly of an organic nature, with a particle size distribution of 0 - 120 µm. Together with air, such products can form an explosive dust/air mixture. A dust explosion may occur when both:
- The concentration of dust in the air is between the Lower Explosive Limit (LEL) and Upper Explosion Limit (UEL).
- A source of ignition of the required energy for the dust cloud is present. Such sources of ignition can include:
(a) hot surfaces or flames
(b) electrical discharges or sparks
(c) electrostatic discharges
A fire may occur when a layer of deposited powder coating or a cloud comes into contact with an ignition source. A fire within a powder coating system may result in a dust explosion if either burning particles are allowed to enter confined sections of equipment, such as dust collectors, or if burning dust deposits are disturbed.
A regular maintenance and cleaning schedule should be introduced to prevent accumulation and build-up of dusts. In the case of electrical equipment, build-up of dusts can result in their ignition through overheating. The maximum temperature of surfaces liable to be exposed to dust, shall not exceed 2/3 of the minimum ignition temperature (= lowest temperature of a hot surface where the most ignitable dust/air mixture is still ignited). Typical powder coatings usually have an ignition temperature of approx. 420-470 °C.
Extract from ‘HSE Reducing risks associated with using coating powders – employers’:
“Practise good housekeeping by keeping work areas around the spray booths clean by using an industrial vacuum cleaner (ATEX compliant and dust tight to IP6X, provided with suitable filtration) rather than sweeping up with a broom.”
The use of compressed air lances, air guns, sweeping and brushing etc are a very old cleaning method that does not reduce risk or exposure to hazardous and explosive dusts. Using these old, dated methods only transfers the dust from one location to another without actually collecting and containing it. ATEX vacuum cleaners are the most efficient way of effectively cleaning and collecting combustible and harmful dusts. They also keep the dusts contained, and then finally, make disposal of the dust safe and easy.
Kerstar’s UK manufactured ATEX certified vacuum cleaners are suitable for ATEX Zone 1, 2, 21 and 22. The Kerstar ATEX range includes the electric powered KEVA series and the compressed air KAV series of industrial vacuum cleaners.
Contact us or your local Kerstar distributor to find out the most suitable vacuum for your needs.