Internationally Approved Product
ULListed
FMApprovedCLA-VAL
A fire pump casing relief valve is a safety valve that relieves a small flow to prevent pressure build-up in the pump casing when the pump runs without water being drawn from the system. Also known as a pump casing relief valve, this accessory has a different function from the main relief valve.
The Cla-Val Model 55L-60 is a direct-acting, spring-loaded, diaphragm-type pressure relief valve. The valve is held normally closed by spring force. When the pressure acting under the diaphragm exceeds the spring setting, the disc lifts off its seat and excess pressure is relieved to atmosphere. When pressure falls below the set point, the spring closes the valve again.
The valve can be installed in any position and opens and closes within close pressure limits. Moving the bottom plug to the inlet converts the flow path to an angle configuration. The adjusting screw can be wire-sealed, and a 1/8″ NPT gauge port allows precise adjustment.
The 1/2″ and 3/4″ sizes are UL listed and FM approved as fire pump casing relief valves; the 1″ size is UL listed. The manufacturer states that the 55L-60 is not suitable for relieving the pump's full rated capacity and that the Model 50B-4KG1 relief valve should be used for that purpose.
| Specification | Value |
|---|---|
| Type | Direct-acting, spring-loaded, diaphragm-type relief valve |
| Size / Connection | 1/2″, 3/4″, 1″ NPT threaded |
| Max. Pressure | 400 psi (bronze and stainless body) |
| Adjustment Ranges | UL: 10–75, 20–200, 20–300, 100–300 psi; FM: 0–75, 20–200, 20–300, 100–300 psi |
| Max. Flow | 1/2″: 25 GPM; 3/4″: 40 GPM; 1″: 65 GPM |
| Max. Temperature | Water, air: 180 °F |
| Material | Body: cast bronze UNS C87850 (standard); trim 303 stainless; Buna-N |
| Approvals | UL 1478A (20150528-EX5218); 1/2″–3/4″ FM Class 1359 |
Technical values are based on manufacturer documents; confirm against the current data sheet before ordering.
Protecting the fire pump casing against overpressure
Pressure trimming in fire protection systems
Fresh water and seawater applications (with suitable body material)Other equipment considered together with the Fire Pump Casing Relief Valve in the fire pump room:
