scope:

This standard encompasses the design and performance requirements for air drying units. In cases where metric sized products are to be examined for Approval, test criteria comparable to the equivalent or nearest nominal inch size shall be used.

Approval Standards are intended to verify that the product described will meet stated conditions of performance, safety and quality useful to the ends of property conservation.

Purpose

This standard states FM Approvals criteria for air drying units for use in dry pipe and refrigerated area sprinkler system piping. They provide compressed air, with reduced humidity, to the sprinkler piping to reduce the possibility of ice formation. 

Approval criteria may include, but are not limited to, performance requirements, marking requirements, examination of manufacturing facility(ies), audit of quality assurance procedures, and a follow-up program.