When a Calibrated Leak's Certificate Expires Mid-Project
A leak-testing lab's helium leak detector is calibrated daily with a calibrated leak certified at 1×10⁻⁷ atm·cc/s. The certificate for the calibrated leak expires in three days. A production lot of 40 components must be tested and shipped within two days, and each component's acceptance depends on the detector reading being traceable to a valid calibration. A replacement calibrated leak is on order but will not arrive for a week. The lab supervisor asks the Level III whether the lot can be tested and shipped using the current calibrated leak before its certificate expires.
1. What is the correct disposition, and why?
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The lot can be tested and shipped only if every test is completed and the detector calibration is valid at the time of each test - i.e., the calibrated leak certificate has not expired. Testing within the two-day window while the certificate is still valid is acceptable, provided: (1) the daily calibration is performed and documented with the still-valid leak; (2) the detector's calibration is verified before and after the lot (bracketing) to demonstrate stability; (3) records show the certificate was valid on the test date. Shipping is a separate question: the test results are valid if obtained under valid calibration. The lab should not extend or backdate the certificate, and should not test after expiry without a valid replacement or an approved alternative traceable standard.
2. What if a component fails and must be retested after the certificate expires?
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The retest cannot rely on the expired calibrated leak. Options: (1) obtain another traceable standard (a loaner calibrated leak, a certified flow standard, or a reference leak cross-checked against a traceable standard); (2) send the component to a lab with valid calibration; (3) if the procedure permits, use an alternative method with its own valid calibration. The failed component's original result remains valid (obtained under valid calibration), but the retest must be performed under valid calibration or the result is not traceable and cannot be used for acceptance. Document the calibration status on the retest record.