Spring-loaded relief valves should be viewed as supplements and not substitutes for a safety rupture disc as the primary means protecting the vessel and the operator 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 stainless steel and have FKM O-rings. Other valve and O-ring materials are available on special order.
| Relief Valves | ||
| Part No. | Relief Pressure Range psi | Discharge Connection |
| A140VB2PA | 50-150 | 1/4″ NPT (M) |
| A140VB2P1 | 50-150 | 1/4″ NPT (M) |
| A140VB2PB | 150-350 | 1/4″ NPT (M) |
| A140VB2PC | 350-600 | 1/4″ NPT (M) |
| A140VB2PD | 150-350 | 1/4″ NPT (M) |
| A175VB | 750-1500 | 1/4″ NPT (F) |
| A175VB2 | 1500-2250 | 1/4″ NPT (F) |
| A175VB3 | 2250-3000 | 1/4″ NPT (F) |
| A175VB4 | 3000-4000 | 1/4″ NPT (F) |
| A175VB5 | 4000-5000 | 1/4″ NPT (F) |
| A175VB7 | 350-750 | 1/4″ NPT (F) |
| A175VB8 | 50-350 | 1/4″ NPT (F) |