Class 1, Div 1 Parameters:

(1) Ignitable concentrations of flammable gases or vapors may exist under normal operating conditions; or
(2) Ignitable concentrations of such gases or vapors may exist frequently because of repair or maintenance operations or because of leakage; or
(3) Breakdown or faulty operation of equipment or processes might release ignitable concentrations of flammable gases or vapors, and might also cause simultaneous failure of electric equipment