Readings That Do Not Add Up
A tester submits a report for a 2-inch RPZ at a car wash. Readings: static supply pressure 78 psi; check valve No. 1 differential 4.2 psi; check valve No. 2 differential 0.8 psi; relief valve opening point recorded as 3.5 psi below the No. 1 check differential. The tester marked the assembly 'PASS.' The gauge calibration sticker is dated 20 months earlier. The report shows the same serial number for a second assembly at the same address, and the tester's signature appears on both reports, timed four minutes apart at addresses 6 miles apart. The program requires annual testing, a 5.0 psi minimum for the No. 1 check, 1.0 psi for the No. 2 check, and relief opening at least 2.0 psi below the No. 1 differential.
1. Evaluate each reading against the program criteria and state the correct test result with your reasoning.
Read the worked answer
No. 1 check: 4.2 psi. Below the 5.0 psi minimum, so it does not hold the required differential - fail. Likely a worn disc, debris on the seat, or a damaged seat. No. 2 check: 0.8 psi. Below the 1.0 psi minimum - fail, marginal but out of criteria. Relief valve. The report says it opens 3.5 psi below the No. 1 differential, which is 4.2 - 3.5 = 0.7 psi absolute opening point. The relief must not open below 2.0 psi, and it must open at least 2.0 psi below a 4.2 psi check differential, that is, at 2.2 psi or lower - but not as low as 0.7 psi. An opening at 0.7 psi means it opens far too easily: fouled or damaged seat or disc, debris, or a damaged sensing passage. Fail.
Overall: the assembly fails on all three elements, and 'PASS' is unsupportable on the face of the numbers. Correct action is a failed report, notification of the customer and the utility, repair by qualified personnel using OEM parts, and retest before the assembly is relied on.
2. Address the gauge calibration and the conflicting entries. What should the program administrator do?
Read the worked answer
Reject the report outright. A test conducted with a gauge 20 months past calibration is not a valid test, because every differential in it is unverified; the numbers cannot be relied on even where they might have passed. The instrument requirement exists so that a 5.0 psi threshold is meaningful.
The duplicate serial number and the four-minute, six-mile interval are worse than a paperwork error. Either the reports are fabricated, or assemblies are unlabeled and the tester guessed, or the same assembly was tested twice and one report was copied. Any of those puts the public supply at risk and undermines the entire program, so treat it as an enforcement matter:
- Require retest of both assemblies by a different certified tester, with the utility present.
- Pull that tester's last 12 months of reports and look for patterns: identical readings, sequential serial numbers, impossible travel times.
- Notify each affected customer in writing.
- Refer to the certification body with the documented basis, and suspend acceptance of the tester's reports pending review, following the program's due process.
Keep the rejected report in the file with the disposition noted; do not delete it.
3. The assembly passes a retest with a different tester six days later. What goes in the record, and does the earlier failure disappear?
Read the worked answer
Nothing disappears. The record shows an initial invalid test, a failed assessment, a repair or adjustment, and a passing retest - that sequence is the compliance history and is exactly what an auditor or a claims investigator will ask for later.
The file should hold: the rejected report and the reason (instrument out of calibration, conflicting entries); the enforcement correspondence; the repair invoice listing parts and the technician; the retest report with gauge calibration date, tester certification number, and all measured values including the No. 1 and No. 2 differentials and relief opening point; and the next annual due date, calculated from the retest, not from the original test.
The earlier 'PASS' should be superseded in the database but retained as an attachment. If the utility tracks compliance status, mark the assembly as having been out of compliance from the original test date until the retest, and note that the site was a health hazard served without verified protection for that interval.