Pressure Relief Valves

A175VB Relief Valve
A175VB Relief Valve
A140VB2 Relief Valve
A140VB2 Relief Valve

Spring-loaded relief valves should be viewed as supplements and not substitutes for a safety rupture disc. The rupture disc is the primary means for protection of the operator and the vessel in case of accidental over-pressure. Spring-loaded relief valves can be added to a reactor or vessel to:

  • Relieve pressures near the maximum operating pressure.
  • Reseal once excess pressure has been relieved.
  • Protect low pressure components at pressures below available rupture disc ranges.

The relief valves listed below can be installed on any Parr vessel. These relief valves are constructed of stainless steel and have FKM O-rings. Other valve and O-ring materials are available on special order. Relief valves with CE Certification are also available.

Pressure Relief Valves for Low Pressures
Part No. Preset psi Adjustable psi Bar Discharge
A140VB2PA 100 50-150 3.45-10.3 1/4″ NPT (M)
A140VB2P1 150 50-150 3.45-10.3 1/4″ NPT (M)
A140VB2P2 145 50-150 3.45-10.3 1/4″ NPT (M)
A140VB2PB 200 150-350 10.3-24.1 1/4″ NPT (M)
A140VB2PC 600 350-600 24.1-41.4 1/4″ NPT (M)
A140VB2PD 300 150-350 10.3-24.1 1/4″ NPT (M)


Pressure Relief Valves for High Pressures
Part No. Relief Pressure
Range, psi
Bar Discharge
A175VB 750-1500 52-103 1/4″ NPT (F)
A175VB2 1500-2250 103-155 1/4″ NPT (F)
A175VB3 2250-3000 155-207 1/4″ NPT (F)
A175VB4 3000-4000 207-276 1/4″ NPT (F)
A175VB5 4000-5000 276-345 1/4″ NPT (F)
A175VB7 350-750 24-52 1/4″ NPT (F)
A175VB7CH (Hast C) 350-750 24-52 1/4″ NPT (F)
A175VB8 50-350 3.4-24.1 1/4″ NPT (F)
A175VB8CH (Hast C) 50-350 3.4-24.1 1/4″ NPT (F)

 *Note: When ordering any of the above relief valves, the user may specify a desired set pressure.

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