Air Compressor Safety Relief Valves vs. Pressure Relief Valves : Placement, Setpoints, Buying Guide

Posted by IAP on 09/30/2025

Tanks don’t “leak safe,” they fail hard. In compressed air systems, the difference between a safety relief valve (SRV) and a pressure relief valve (PRV) isn’t semantics; it’s fundamental safety. SRVs protect receivers and compressor packages from catastrophic overpressure. PRVs protect piping segments and components from minor excursions. Misapplying one for the other creates real risk.

Below is the compressed-air–specific guide you can hand to maintenance: clear definitions, setpoint logic, where each valve belongs, fast sizing tips, and what to buy.

Quick Links

What Each Valve Actually Does - Compressed Air Only

Safety Relief Valve (SRV)

  • Purpose: Mandatory protection on air receivers (and often on compressor packages) to rapidly vent if pressure exceeds the vessel’s safe design limit, preventing a tank from becoming a projectile.
  • Behavior: “Pop” action opens quickly at the setpoint and re-seats after pressure drops (blowdown).
  • Where: Directly on receivers and package vessels; no shutoff valve between the vessel and SRV.

Pressure Relief Valve (PRV)

  • Purpose: Protects piping segments and components (filters, dryers, heat exchangers, headers) from minor overpressure caused by regulator drift, thermal expansion, or control faults.
  • Behavior: Often modulating/relieving, opens enough to hold pressure near setpoint.
  • Where: On vulnerable segments downstream, not in place of the receiver’s SRV.

Shop Air Compressor Valves

→ Safety Relief Valves

→ Pressure Relief Valves

Safety Relief Valve Setpoints & Behavior 

Safety Relief Valves (SRV) Setpoint - Receivers & Packages

  • Set at or below the vessel’s MAWP (maximum allowable working pressure).
  • Capacity matters: Choose an SRV with relieving capacity greater than the total compressor CFM feeding that vessel so pressure can’t outrun the valve.
  • Blowdown: Needs to be appropriate; too tight can cause chatter; too loose wastes air. Choose reputable SRVs with documented re-seat behavior.

Pressure Relief Valve (PRV) Setpoint - Piping/Components

  • Set slightly above normal operating pressure to avoid nuisance lift, but below the lowest-rated component in that protected segment.

Pro tip: Regulators aren’t relief devices; relief valves aren’t regulators. Use both correctly to avoid hunting and unexpected lifts.

Where Each Valve Belongs (Fast Placement Map)

Safety Relief Valves SRV (Required):

  • On every air receiver.
  • Install vertically, with an unobstructed discharge and no isolation valve between the SRV and vessel nozzle.
  • On packaged compressors, keep the OEM SRV in place and sized for the package’s internal vessel

Pressure Relief Valve PRV (Recommended):

  • At dryer outlets and filter housings (thermal expansion can spike pressure in trapped segments).
  • On isolated headers fed by regulators or controls that can drift.
  • At aftercooler/heat-exchanger outlets, where temperature swings change density and pressure.

Sizing & Selection in Five Minutes

  1. Connection & Capacity
    • Match NPT size to the port
    • For SRVs, confirm nameplate capacity ≥ total compressor CFM feeding the receiver.
  2. Set Pressure
    • SRV: ≤ vessel MAWP
    • PRV: Just above normal operating pressure, but below the weakest rated component in that segment
  3. Materials & Elastomers
    •  Choose for clean, dry air or for environments with condensate/oil carryover and temperature swings
  4. Serviceability & Traceability
    •  Prefer tagged, sealed valves with clear setpoint and date; keep spares on hand for critical assets

Ready to Buy?

→  Safety Relief Valves (1/4"–3" NPT)

→ Pressure Relief Valves (Altec, Atlas Copco, Champion, CompAir, Gardner Denver, Great Lakes Air, Ingersoll Rand, LeRoi, Quincy, Sullair, Van Air)

Want to Speak with an Expert Before Ordering?

→ Contact IAP here or call (414) 422-1717 for product selection help

Inspection & Changeout Habits That Actually Prevent Risk

  • Look For: Weeping/leakage at the outlet, corrosion, missing/damaged tags, tamper-seal issues, or chatter history.
  • Replace If: Unknown age, wrong setpoint for the vessel, evidence of sticking, or after any significant overpressure event.
  • Don’t Isolate SRVs: Never install or close a valve between a receiver and its SRV.
  • Log It: Record setpoint, install date, and last lift/replace date just like any other safety device. Keep relief devices part of your PMs.

Buy with confidence from IAP

When safety is on the line, you want fast, correct parts, not guesswork. For fast SKU matching, search by part number, model, or brand, or get help from IAP product experts. Get Started today:

  • Create an IAP account to centralize purchasing for unmatched pricing, consistent availability, and fast shipping
  • Get the right products
    • Safety Relief Valves (SRV): IAP stocks a complete line from 1/4" to 3" NPT → filter by PSI and size in seconds
    • Pressure Relief Valves (PRV): Multi-brand selection: Altec, Atlas Copco, Champion, CompAir, Gardner Denver, Great Lakes Air, Ingersoll Rand, LeRoi, Quincy, Sullair, and Van Air) → browse here
  • Contact IAP if you have any questions or prefer to speak with one of our experts

    FAQ

    Are SRVs and PRVs interchangeable?

    No. SRVs are rapid-vent safety devices for receivers/packages; PRVs protect piping/components. Use both where appropriate.

    Can I put a shutoff valve under an SRV?

    No. Never isolate an SRV from the vessel it protects.

    Do small/portable receivers need SRVs?

    If it’s a pressure vessel, it needs appropriate overpressure protection. Check the vessel rating and follow OEM guidance.

    Can I muffle/silence a relief valve?

    Use only rated discharge accessories that do not restrict flow. Do not improvise with fittings that could choke relief capacity.

    Next Steps (Choose → Install → Log)

    • Verify your vessel ratings and operating pressures.
    • Select the correct valve type and setpoint for each location.
    • Install per good practice (vertical, unobstructed discharge, no isolation on SRVs).
    • Log setpoints and dates; add relief devices to your PM schedule.

    Prefer to Talk Through What You Need?

    Contact IAP here or call (414) 422-1717 for product selection help

    Streamline Your Complete Compressor System

    → Shop All IAP Products

    Safety Note: Perform all work only after proper lockout/tagout and full depressurization. Use OEM-rated components; never bypass or isolate safety devices. Electrical diagnostics should be handled by qualified personnel.

    Related Articles