Valve remains closed during normal usage. Automatically opens on a drop in downstream pressure. Provides fire flow at higher outlet pressure. Trip point and outlet pressure are both adjustable. Valve is manually reset to return to normal flow. Adjustable opening/response speed. Can be maintained without removal from the line. Available sizes: screwed ends - 1¼ - 3", grooved ends - 1½ - 6" and flanged ends -1¼ - 24" (globe) and 1¼ - 16" (angle). Body bonnet is made of ductile iron per ASTM A536, Grade 65-45-12. Ferrous surface is coated with 4 mils of epoxy.