Pressure Reducing Valve accessories type CRL & 55L | Cla-Val

Cla-Val CRL & 55L Pressure Control Accessories

The Cla-Val CRL & 55L are auxiliary pressure control devices used in pilot circuits and fire protection systems. Product documentation classifies them as pressure reducing valve accessories, while the 55L technical datasheet specifies it as a direct-acting, spring-loaded, diaphragm type pressure relief valve.

55L Operating Principle

The 55L remains normally closed due to spring force above the diaphragm. When control pressure beneath the diaphragm exceeds the spring setting, the disc lifts off the seat, venting excess pressure to atmosphere. When pressure drops below the setpoint, the spring returns the valve to the closed position.

Technical Data

• Type: Pressure relief valve / pressure relief control
• Operation: Direct acting, spring loaded, diaphragm type
• Sizes (55L): 1/2" and 3/4"
• Connection: Threaded
• Max temperature (water/air): 82 °C
• Body pressure rating: 400 psi
• Set pressure ranges: 0–75 psi, 20–200 psi, 100–300 psi
• Body materials: Low lead bronze or stainless steel (depending on version)
• Elastomer: Buna-N synthetic rubber

Pressure Adjustment

Adjustment is via the set screw. Clockwise rotation increases set pressure. After adjustment, locknut must be secured; cap can be wire-sealed to prevent unauthorized changes.

Typical Applications

• Fire protection systems
• Closed piping systems with overpressure risk
• Cla-Val pilot circuits
• Auxiliary water or air networks
• Systems requiring local pressure relief

Selection and Maintenance Considerations

Selection should be based on set pressure, spring range, media, temperature, and elastomer compatibility. Maintenance includes inspection of diaphragm, seat, spring, control orifices, and removal of deposits that may affect opening pressure.