It consists of two parts. Other filters are available that can be used with inorganic vapors and specific chemicals. There are no filters available for use in atmospheres containing fumigants, carbon monoxide, natural gas or against organic vapors which generate high heats of reactions. Be sure the unit that you purchase has this approval. After placing the helmet over the head, the drawstring is tightened to form a seal at the neck.
Some manufacturers have an adapter that attaches the helmet directly to a protective suit.
The airflow speed is selected next, then the visor is closed to seal the unit. In most units the exhaust vents on the helmet can be regulated to obtain the desired positive pressure. To keep the protective helmet system in good operating order the correct storage and maintenance procedures should be followed. After use, the helmet shell should be cleaned with soapy water. Care should be taken not to scratch the face shield.