During the manufacturing of explosive devices such as munitions, fireworks or flares, uncontrolled static electrical discharge presents a high risk to the combustible materials being processed. By maintaining a humidity of 55%rH static build-up is avoided as the moisture acts as a conductor and dissipates any electrical charge generated by friction.
Thermohygrographs are used to record the temperature and humidity in explosive manufacturing facilities so that the environmental conditions munitions are produced under can be traced back and checked should a defect be identified in the field at a later date.
Both in-room and in-duct humidifiers are used in these environments but they must be ATEX explosion proof and intrinsically safe. JetSpray compressed air and water humidifiers are popular as, unlike steam humidifiers, they do not contain electric heating elements and still provide very close control over the humidity to within +/-1%rH.