Test Procedure Error: Gauge Calibration and Its Effect on Results
A tester is testing a reduced-pressure assembly at a hospital. The tester's differential gauge was last calibrated 18 months ago, and the calibration sticker is faded. During the test, the first check reads 4.8 psi, which is just below the typical minimum of 5.0 psi. The tester is under time pressure because the hospital needs the water back on. The tester considers recording the reading as 5.0 psi to pass the assembly, or using a second gauge that is properly calibrated. The second gauge reads 5.3 psi on the same check. The tester must decide which result to report and how to handle the calibration issue.
1. Which gauge reading should the tester report, and why is the calibration status important?
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The tester should report the reading from the properly calibrated second gauge, which is 5.3 psi, and should not report the 4.8 psi reading from the out-of-calibration gauge. A gauge that has not been calibrated within the required interval cannot be relied upon for a valid test result. The calibration sticker being faded is a warning sign that the gauge may be out of tolerance. The tester should remove the out-of-calibration gauge from service, document the calibration status, and use the calibrated gauge for the test. The report should include the gauge's calibration date and serial number so the result can be traced. Recording a false 5.0 psi to pass the assembly would be falsification and is unacceptable.
2. What should the tester do about the out-of-calibration gauge, and how should the report reflect the situation?
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The tester should tag the out-of-calibration gauge as out of service, remove it from the test kit, and arrange for recalibration before it is used again. The tester should record in the report that a second, calibrated gauge was used and that the first gauge was found to be out of calibration. The report should include the calibration dates and serial numbers of both gauges, the readings obtained with the calibrated gauge, and a statement that the out-of-calibration gauge was not used for the final result. The tester should also notify the employer or supervisor so that the gauge can be recalibrated and the calibration schedule can be reviewed. This protects the tester and the hospital and ensures the test result is defensible.