StamparioBackflow test readings check
On a reduced-pressure (RP) assembly, many utility and CSA-based forms ask for a relief valve opening of at least 2 psid and a buffer of at least 3 psid between the check valve #1 pressure drop (A) and the relief opening (B). Double-check assemblies are commonly held to at least 1 psid per check, and PVB/SVB air inlets and checks to at least 1 psid. Your test procedure manual and water utility decide pass or fail.
| Relief valve opened at (B) | 3.2 | ≥ 2 |
| Buffer C = A − B | 3.2 | ≥ 3 |
| Check valve #1 (A), where a utility prints 5.0 | 6.4 | ≥ 5 |
Where the numbers come from
Canadian municipal forms based on CSA B64.10.1 print the buffer rule directly: relief opening "2 psi or greater" and buffer C = A − B "3 psi or greater" (Toronto; Capital Regional District, BC). Some US utility forms print their own minimums, such as 5.0 psid for check valve #1 on an RP.
What the check doesn’t cover
Closed-tight results, whether the air inlet opened fully, shut-off valve tightness and the test procedure itself. Those stay on the report.
Common questions
Is a buffer below 3 psid a fail?
On forms that print the 3 psid buffer rule, yes. Otherwise follow your procedure manual and utility.
Does Stampario calculate the buffer on the report?
Yes. The Canadian backflow report works out C = A − B for the initial test and the re-test.
Sources
- City of Toronto: backflow prevention device test report (buffer C = A − B)
- Capital Regional District (BC): backflow preventer test report, 2025
- Liberty Utilities: test and maintenance report (5.0 psid CV1 minimum)
Codes change by edition and the authority having jurisdiction (your fire marshal, water purveyor or state agency) decides which rules apply. This page is general information, not legal advice.