This device only prevents the irrigation system from backflow. In Missouri we are required to have these in the lawn irrigation systems , not the house water system.
All manufactures recommend removal of the backflow device in cold winter areas. They also say in the manuals to never blow through the backflow, although every sprinkler company I know of blows through the backflow when winterizing the system. I have had to replace the seals, springs, diaphram , and o-rings twice in the last 5 years and suspect this was caused by the compressed air.
Now I am looking for fittings that would screw on the 1 inch union (male end) and connect to the air compressor hose for blow out.