The Model 55L-60 is normally held closed by the force of the compression spring above the diaphragm. When the controlling pressure applied under the diaphragm exceeds the spring setting, the disc is lifted off its seat, permitting flow through the control. When control pressure drops below the spring setting, the spring forces the control back to its normally closed position. The controlling pressure is applied to the chamber beneath the diaphragm through an internal passage. A gauge port is provided for accurate pressure setting.

Pressure adjustment is done by turning the adjusting screw to vary the spring load on the diaphragm. The 55L-60 is available in pressure ranges suited to agency approval tests. To prevent tampering, the adjustment cap can be wire sealed by using the lock wire holes provided in the cap and cover.

Features:

• Sizes 1/2” and 3/4” are UL Listed and FM Approved for use as Fire Pump Casing Relief Valves
•  The 1” model is UL Listed for use as a Fire Pump Casing Relief Valve
•  Direct Acting - Precise Pressure Control
•  Drip Tight Closure
•  No Packing Glands or Stuffing Boxes
•  Globe or Angle configurations available
•  Sensitive to Small Pressure Variations
•  Meets low lead requirements
•  Available in Cast Bronze, 316 Stainless Steel, monel & Super duplex Stainless Steel

Typical applications:

The Model 55L-60 is typically used in a fire protection system to trim water pressure, thus preventing pressure build-up whenever line pressure exceeds the setting of the spring.