The differential pressure by-pass valve is used in systems with a fixed speed circulating pump supplying several zones controlled by two way zone valves. This valve ensures that the head pressure of the pump is proportional to the number of two way valves being closed. It will by-pass the differential pressure created by the pump as the zone valves close, thus eliminating water hammer noise. The 519 series is available with conventional NPT and sweat union connections. Also available for size 3/4", the Presscon copper tailpiece with union nut makes installation and maintenance fast, easy and efficient. Special slots in the EPDM O-ring allows fluid to leak during system testing if unpressed and provide a perfect leak proof seal when completely pressed.

Caleffi Differential Pressure By Pass Valve, 519 Model, 3/4 in Nominal, NPT Connection, 9 gal/min, 150 lb/sq-in Maximum Working, 2 - 10 lb/sq-in Adjustable Pressure, Brass Body and Valve Plug, Stainless Steel Spring, EPDM Valve Plug Gasket and O-Ring Seal, NBR Union Seal and ABS Control Knob, 32 - 230 deg F, 5-11/16 in L

• Instruction/Installation Manual https://assets.unilogcorp.com/267/ITEM/DOC/Caleffi_519502A_Manual.pdf
• Specification Sheet https://assets.unilogcorp.com/267/ITEM/DOC/Caleffi_519502A_Specification_Sheet.pdf