How to prevent powder dust explosion
An explosion can be prevented if both or either of the conditions Explosive Limit and Source of ignition are avoided. Powder coating system should be designed to prevent both conditions occurring ,but due to the difficulty of totally eliminating sources of ignition,more reliance should be placed on the prevention of explosive concentrations of powder. This can be achieved by ensuring that the powder in air concentration is kept below 50% of the Lower Explosive Limit(LEL).
Determined LELs on the range of typical powder coatings lie between 20g/m3 and 70g/m3 dependent on the specific chemical and physical properties.The application unit should be clearly marked with the capacity of the extraction unit and the maximum number and capacity o the spray guns. The configuration of the unit and coating powder usage should be regularly checked against stated values to ensure that airborne concentrations do not exceed 10g/m3.
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 use of compressed air or dry brushing for cleaning up spills for cleaning down equipment should be avoided. Suitably designed dust tight vacuum cleaners or wet brushing are preferred methods.
Smoking should be strictly prohibited and all sources of ignition,such as matches and lighters should be excluded.