Hydraulic Pressure Control Valves - 50-33 & 650-33 Back Pressure Shutoff Safety Valve with Manual Reset | Cla-Val

Cla-Val 50-33 / 650-33

Hydraulic pressure shut-off safety valve with manual reset. Designed to protect downstream installations when outlet pressure from a primary PRV exceeds the specified limit. Provides positive isolation rather than pressure relief.

Operation

The valve continuously monitors downstream pressure. If the setpoint is exceeded, it closes and remains closed until manually reset. This logic is suitable where pressure relief alone is insufficient and positive network isolation is required for safety or process integrity.

Applications

• Potable water networks downstream of high-capacity PRVs
• Protection of downstream pipelines and fittings
• Fire water distribution systems
• Industrial supply lines where overpressure requires isolation
• Installations with critical operating pressure limits

Variants

• 50-33: Full port, suitable for higher flow rates.
• 650-33: Reduced port, for lower flow applications or where tighter control is required.

Construction

• Connection: Flanged
• Standard: ANSI
• Pressure Classes: 150 lbs, 300 lbs
• Materials: Brass, ASTM A216 WCB, ductile iron

Selection Criteria

Selection is based on upstream PRV set pressure, maximum allowable downstream pressure, flow rate, network hydraulic profile, and reset procedure after trip. Media compatibility and maintenance access should also be considered.

FAQ

Is this a relief valve?
No. It does not vent pressure; it isolates the downstream network upon overpressure.

Does it reset automatically?
No. Manual reset is required after confirming the cause of overpressure has been addressed.