english 
Vacuum Relief Valve (VRV) Testing Protocol
Proper testing of a vacuum relief valve (VRV) is essential to prevent tank collapse, vapor lock, and hazardous pressure imbalances. Follow this professional testing protocol:
1. Pre-Test Preparations
- Safety First: Work in a well-ventilated area with PPE (gloves, goggles).
- Isolate the Tank: Ensure no gasoline transfer occurs during testing.
- Clean the Valve: Remove debris from the valve seat using a non-sparking brush and solvent-compatible cleaner.
2. Manual Function Test
- Visual Inspection: Check for corrosion, cracked springs, or damaged seals.
- Movement Test: Gently lift the valve diaphragm with a plastic tool—it should move freely without sticking.
- Seal Check: Apply a soap solution to the closed valve; bubbles indicate leaks.
3. Pressure/Vacuum Bench Test
- Test Rig Setup: Connect the VRV to a vacuum pump and pressure gauge.
- Cracking Pressure Test:
- Slowly increase vacuum until the valve opens (typically -0.5 to -1.5 psi for gasoline tanks).
- Verify against the manufacturer’s specs (e.g., ±10% tolerance).
- Reseal Test: Reduce vacuum to confirm the valve fully closes at ≥90% of opening pressure.
4. Field Verification
- Operational Test: During tank refueling, listen for a hissing sound as the valve relieves vacuum.
- Ultrasonic Detector: Use an acoustic leak detector to confirm valve activity.
5. Documentation & Compliance
- NFPA 30 Requirement: Test VRVs annually or per local regulations.
- Record Keeping: Log test dates, pressures, and any replacements.