PVB test procedure, step by step.

Before you test: N.I.I.O.

Notify, Identify, Inspect and Observe, in that order, before a hose goes on.

Notify

• Tell the owner or whoever is on site that water past the assembly is about to go off, and for how long.
• Ask what is on the line before you close a valve: anything that cannot lose water or pressure, such as dialysis, boilers, medical or process equipment, livestock waterers or fire protection.
• Notify the water system too, if its program asks for notice before a test.

On a PVB:

• Most PVBs feed irrigation. Ask the owner to keep the controller from starting a zone while you test.
• The air inlet will spill water when it opens. Warn anyone nearby.

Identify

• Copy make, model, size and serial number off the assembly itself, not off last year's report. A swapped assembly is a new record.
• Record where it is on the premises.
• Confirm the assembly type matches the hazard the water system assigned to this connection.
• Confirm it is on the USC Foundation list of approved assemblies for the way it is installed.

On a PVB:

• A PVB protects against backsiphonage only. Confirm nothing downstream can create backpressure.

Inspect

• Inspect before you touch a valve. An assembly that is the wrong type, or installed wrong, fails no matter how it gauges.
• Both shut-off valves operate and hold.
• No visible leaks, cracks or freeze damage.
• Your test kit is in calibration. Most water systems want it calibrated within the last 12 months.

On a PVB:

• Installed vertically and upright.
• At least 12 in. above the highest downstream outlet or point of use.
• Canopy in place, air inlet clear and vent screen intact.
• Both test cocks present, operable and not plugged.

Observe

• Watch the assembly at rest before you start: discharge, drips and noise all tell you something.
• Watch for thermal expansion on a closed system: a water heater downstream of a closed shut-off can spike the pressure.

On a PVB:

• Is water spitting from the air inlet at rest? That points to a dirty or worn air inlet seat.
• Look downstream for anything that could push pressure back: a booster pump, a chemical injector or piping higher than the PVB. Any of these means the wrong assembly.

TC is a test cock. SOV is a shut-off valve. psid is pounds per square inch, differential.

Pressurizing the gauge

1. REMOVE the canopy.
2. FLUSH both test cocks.
3. ATTACH the bleed-off valve arrangement to the #1 TC. Attach the high hose to the #2 TC.
4. PRESSURIZE the gauge by opening the #2 TC. Open the high bleed needle valve to purge air from the gauge, then close the high bleed needle valve.
5. CLOSE shut-off #2.
6. POSITION the gauge with its centerline at the same height as the assembly's air inlet.

Air inlet opening

The air inlet must open before the pressure in the body of the PVB is no less than 1 psi above atmospheric pressure.

7. CLOSE shut-off #1.
8. OPEN the high bleed needle valve no more than ¼ turn. If the gauge will not descend with the valve open ¼ turn, shut-off #1 may be leaking: see troubleshooting.
9. OBSERVE the pressure differential on the gauge at which the air inlet opens.
10. DETACH the gauge hose to let the water drain from the body of the assembly. Observe that the air inlet has fully opened.
    Record the air inlet opening point (must be 1 psid or greater).
11. CLOSE the high bleed needle valve.
12. CLOSE the #2 TC.
13. OPEN shut-off #1.
14. ATTACH the high side hose to the bleed-off valve arrangement on the #1 TC.
15. PRESSURIZE the gauge by opening the #1 TC. Open the high bleed needle valve to purge air from the gauge, then close the high bleed needle valve.
16. POSITION the gauge with its centerline at the same height as the assembly's #2 TC.

Check valve test

The static pressure differential across the check valve must be at least 1 psid.

17. CLOSE shut-off #1.
18. OPEN the #2 TC and wait for the water to stop running. If it does not stop, see troubleshooting: this indicates a shut-off leak.
    Record the static value as the pressure differential across the check valve.
19. CLOSE the TCs, detach the gauge, slowly restore customer service (open SOV #1 first, then slowly open SOV #2), replace the canopy, and complete the test report.

Failure matrix

What can go wrong at each step, what it means, and what goes on the report.

Troubleshooting a PVBA

Many problems are corrected by cleaning the internal components. Carefully observe the condition of the components. Shut-off valves can be re-opened and closed for a better seal. Use lubricants only to help reassemble components, and only non-toxic ones.

Other assemblies

• RPZ test procedure →Reduced-pressure principle backflow assembly (RPBA)
• Double check test procedure →Double check valve assembly (DCVA)
• SVB test procedure →Spill-resistant pressure vacuum breaker assembly (SVBA)

All test procedures →

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