This document specifies a method for the calculation of the lower explosion limit of a coating powder, i.e. the minimum concentration of the coating powder in air which will form an explosive mixture. It is based on the measurement of the gross calorific value of the product, as determined by the method described in ISO 1928.
Reliable methods for the measurement of the lower explosion limit or the gross calorific value require the use of special apparatus which may not be readily available.
A method for determining the explosion indices of combustible dusts in air is given in ISO 6184-1. This method is, however, very intricate and requires considerable expertise.
The lower explosion limit can also be estimated by summation of the gross calorific value of the individual constituents of the coating powder. It is an estimation since the gross calorific value of the constituent may not be known or available.
The calculation method leads to lower explosion limits which have been proved in practice to be satisfactory when applied to coating application plants.
NOTE A comparison with a direct method e.g. EN 14034-3 for determining the lower explosion limit is encouraged.