Maintenance & Reliability · PM Procedure

Air Compressor Receiver Tank Moisture Draining And Valve Check

Standard procedure for the safe and effective removal of condensate from stationary air receiver tanks, accompanied by a mandatory functional test of the safety relief valve (SRV) to ensure compliance with CSA B51 and ASME Boiler & Pressure Vessel Code.

Estimated Time

30 min

Difficulty

Intermediate

Regulation

CSA B51 / ASME

Version

2.3

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Purpose

To remove accumulated condensate and particulate from the air receiver tank to prevent downstream corrosion, maintain system air dryness, and ensure the tank's structural integrity. This procedure also verifies the operability and set-point integrity of the associated safety relief valve (SRV), a critical safety device required by code.

Scope

Applies to all stationary industrial compressed air receiver tanks within the facility operating above 103 kPa (15 psig). Covers shift-based manual draining (where auto-drains are absent or backed up) and the monthly SRV manual lift test. Does not cover internal tank inspection or hydrostatic testing.

Safety Precautions

LOTODepressurize the receiver tank completely if performing any work downstream of the isolation valve or on the SRV. For manual draining under pressure, open the drain valve slowly. Rapid opening can cause violent spitting of condensate and debris.
PPEWear CSA Z94.3 safety glasses with side shields. Wear leather work gloves to protect against freeze-burns caused by rapid gas expansion across the drain valve. Hearing protection is required if draining into an open drum.
HOTReceiver tank surfaces can exceed 80°C. Allow components to cool where possible, or wear approved thermal protective gloves.
AIRNever point the drain stream at a person, electrical panel, or unsecured object. Compressed air debris can cause severe injury.

Required Tools & Materials

1/2-inch combination wrench (for manual drain valve packing nut if leaking)
Collection bucket or waste oil drum (10 L minimum capacity)
CSA Z94.3 approved safety glasses and leather work gloves
Flashlight for visual inspection of drained fluid and tank bottom
Lockout/tagout kit (if isolation is required for SRV work)
Soap-and-water solution in a spray bottle (for SRV seat leak check)

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Procedure: Step-by-Step

1 Locate the air receiver tank. Identify the manual drain valve (typically a ball valve or needle valve at the bottom center). Verify the pressure gauge reads normal system operating pressure. Do not proceed if the tank is fully pressurized and the drain valve appears damaged or missing.

2 Position the collection bucket securely under the drain valve outlet. Ensure the bucket is grounded if flammable vapours may be present.

3 Slowly open the manual drain valve 1/4 to 1/2 turn. Listen for the rush of air and condensate. Caution: Rapid opening can cause violent spitting of hot oil, water, and rust particles.

4 Drain until a steady stream of dry air is observed (no visible water droplets). Depending on humidity and system load, this may take 15 to 45 seconds. Close the drain valve hand-tight. Do not overtighten (damage to the valve seat or packing may result).

5 Proceed to the safety relief valve (SRV) located on top of or adjacent to the receiver. Visually inspect the SRV tag for required set pressure (e.g., 150 psi) and the most recent test date. Report any missing tags or outdated inspections.

6 Perform a manual SRV lift test: Slowly lift the ring or lever on the SRV for 2–3 seconds. A loud pop of released air confirms the valve is not seized. Release the lever quickly. Caution: Steam or hot condensate may be discharged during this test.

7 Check for SRV seat leakage after the test. While the system is pressurized, apply soap-and-water solution to the SRV outlet. The absence of continuous bubbling indicates a tight seal. Continuous weepage or bubbling = valve failure. Tag out and schedule replacement immediately.

8 Record the drain time, estimated water volume drained, and SRV test status (Pass / Fail) in the PM logbook or CMMS. If using ServiceGrid, log the reading directly against the asset profile to trigger trend alerts.

Air Compressor Receiver Tank Moisture Draining And Valve Check

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