The second most common calibration proficiency deficiency for ISO 17025 compliance is related to infractions in ISO 17025 Section 5.5, Equipment. The nature of calibration requires using the proper equipment with known performance, traceability and reliable operation. While this is clearly core to the accurate operation of calibration, ironically, the compliance violations in this area are very common.
As far as complying with the Equipment section 5.5 of ISO17025, a leading deficiency can be as simple as failing to validate the proper operation and results of the calibration equipment/test system anytime after the equipment has been over ranged or abused. The reason for doing this is simple… you just don’t know what may have happened to the equipment without checking it. Prudent operation dictates revalidating the operation and results to ensure quality.
While this revalidation certainly costs time/money, this is an expected cost of doing business, especially if you choose to share equipment between test stations. In startup operations, there is often the need (or is it a temptation?) to share equipment since investment capital is limited, systems are not running anywhere near capacity and many calibration/test systems have common components like volt meters, etc. However, as equipment is shared, the risk in problems typically goes up. Accidental drops, operator error/over-ranging, Electro-Static Discharge (ESD) and even errors in re-cabling the sensor hookups are all suspect when sharing equipment. To ensure control/validity, you can quickly see why most metrology labs move to dedicated equipment per test station as fast as their sales/profitability and cash flow allow.
The same validation is needed if the equipment has left your direct control allowing it to have undergone or even if it's suspected to have undergone misuse, overload or damage. This is especially key in terms of a “suspected” case. Could it have been dropped? Could someone have been adjusting mechanical settings? Could it have experienced an extreme environment in temperature? How about transport vibration? Or even been subjected to ESD? Any or all could have potentially adverse affects to the performance of your calibration or test system. Accordingly, verifying against “the unknown” is a mandatory part of judicious calibration laboratory operation. It's certainly easier in the short run to turn a blind eye to potential problems and just run with the equipment/system “as is”, but in the long run, careful and thorough validation of the system and results ensure that your lab will avoid the pain, the expense, the loss of reputation and the potential lawsuits possible with recalled service work.
Another commonly missed checkpoint is actually starting with new equipment or test systems. As intuitive as it may sound, at the point of commissioning, the equipment must be properly calibrated with system results validated before placing the calibration/test system into service. A solid practice is to have the same validation sensor (or set of sensors) calibrated at your vendor prior to shipping (Factory Acceptance Test – FAT), then calibrated upon system installation at your site (Site Acceptance Test – SAT) and then select one of the sensors as your daily verification sensor to be continually checking and logging the effects of any variance in system, environment or operator. This process, along with keeping precise equipment records, uncertainty calculations, equipment operation manuals and specific test procedures, form the backbone of the reliable operational and proven trust in the methodology and system.
Again, we see the key words of metrology surfacing. Precision, Uncertainty, Reliability, Proof, and Trust… These words should be typical of your calibration program, typical of your people, typical of your choice in sensor and instrumentation supplier and typical of your choice in calibration service provider. Leverage our experience. We’re here to answer your questions, so go ahead and ask! How can we help you?
End note: The inspiration for the content in this month’s article comes from a presentation at a regional meeting of NCSLi. Of particular interest and usefulness, our Calibration Product Group Manager brought back an excellent presentation by Mr. Robert Knake of A2LA addressing the "Most Common Deficiencies" found during the ISO17025 assessment audit process. We thank Mr. Knake and the A2LA organization for the approval to reprint his presentation.