Compressor Relief Valves — Air & Gas Protection
Compressor relief valves prevent dangerous overpressure, protect the compressor from deadheading, and maintain optimal system pressure. Aquatrol’s guide covers sizing for rotary and reciprocating compressors, selecting direct-acting versus pilot-operated designs, and troubleshooting common relief valve failures. Instant sizing recommendations and field-adjustable pressure settings.
Compressor Relief Valve Essentials
Compressors continuously generate high-pressure air or gas. Without proper relief protection, a clogged discharge line, closed downstream valve, or pressure spike can damage the compressor, burst hoses, and create safety hazards. The relief valve senses discharge pressure and opens to exhaust excess air when the system reaches the set pressure, protecting equipment and operators.
Sizing a relief valve requires matching the valve capacity to the compressor displacement at full load. Oversizing causes system deadheading (compressor discharge blocked, excessive heat and noise) and preventable cycling; undersizing fails to relieve pressure adequately. Our sizing calculator uses compressor type, CFM rating, and discharge temperature to recommend the correct series and setting.
Direct-acting valves are simpler and lower-cost for small compressors (under 500 CFM). Pilot-operated designs provide better pressure stability and lower back pressure for larger systems or where constant system pressure is critical. Both respond quickly to pressure spikes and protect the compressor from failure.
| Compressor Type | Displacement | Series | Pressure Range |
|---|---|---|---|
| Rotary screw | 50–500 CFM | 55, 140 | 50–500 PSIG |
| Rotary screw | 500+ CFM | 120, 141 | 100–1,000 PSIG |
| Reciprocating | 5–50 CFM | 89, 140 | 50–400 PSIG |
| Reciprocating | 50+ CFM | 55, 120 | 50–600 PSIG |
| Gas compressor | Any size | 55, 141, 120 | 50–3,000 PSIG |
Common Applications
- Rotary screw compressor outlet relief and protection
- Reciprocating compressor discharge pressure relief
- Gas compressor overpressure and safety limiting
- Compressed air storage tank and receiver protection
- Portable and mobile compressor pressure control
- Air-driven tool and pneumatic system relief
- Compressor unload valve bypass and capacity control
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