For example, the procedure used for deciding the calibration cycle should be documented with the calibration data recorded for future use, and the person experienced with measurements on similar instruments should make the final decision regarding the calibration interval. The process of time interval estimation between calibrations is a dynamic one. Once a calibration schedule has been established it must be fine-tuned to balance the risks and calibration cost.
There could be many reasons for this, the instrument may be less reliable, the severity of use may differ, and limited calibration may be enough compared to full calibration.
As previously stated, before an optimal calibration cycle can be established, the time interval between calibrations needs to be continually reviewed. The process to finding the best calibration will depend on various factors such as the availability of historical calibration data for the instrument, type of instability in the instrument, whether or not the instruments undergo an adjustment, and if the instrument exceeded the calibration by drift over time or by usage. The following considerations will help you determine the best calibration cycle for your equipment:.
Obviously performing calibrations consumes time and money, doing it too often is a waste of resources. Instrument calibration is one of the most basic of maintenance procedures. The consequences of not calibrating adequately will cost much more than maintaining a good calibration management process. All Rights Reserved. Continue Continue Privacy Notice. Calibration and Calibration Certificates Support.
When should you calibrate your equipment? What does a calibration certificate look like? How Often Is Calibration required? I agree with you Rachel, no quick and easy answer. Here is a good article by Pylon that covers more aspects of the importance of calibration.
Calibration Cycle: General Guidelines Unfortunately, there are no quick answers in figuring out the best calibration cycle. Calibration Cycle: Important Considerations As previously stated, before an optimal calibration cycle can be established, the time interval between calibrations needs to be continually reviewed.
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Close this box to accept cookies whilst browsing our site. Apprenticeships for Learners Apprenticeships for Employers. Gatwick Coventry Leeds Warrington. Blog How often should you calibrate your test equipment? How often should you calibrate your test equipment? How important is Calibration The calibration process compares a measuring instrument with a measurement standard to establish the relationship between the values indicated by the instrument and those of the standard.
Before you start a major critical measuring project - If you have a project that requires highly accurate measurements, firstly decide which instruments you will use and then send them for calibration, then lock them down in storage until testing begins to ensure you get absolutely accurate results.
After a major critical measuring project ends - After a major critical measuring project you should send the same equipment for calibration.
When you get the results back you can confirm the accuracy of your testing results for that project. Per project requirements - Each job regardless of the project size will have a different calibration requirement.
Also, manufacturers often have specified a typical long-term stability for a given time, like for one year. Of course, over time, you should follow the stability of the device and adjust the calibration interval accordingly.
I mean that if the reference standard has a very good accuracy compared to your needs, you may calibrate it less often.
Even if it fails to stay within its specifications, it may not be that critical to you. Also, the other way around — if the reference standard is on the limit of being accurate enough for you, you may want to calibrate it more often than the manufacturer recommends, as you may want to keep it in tighter tolerance than the manufacturer's specifications are. The stability history of any measurement device is very precious information.
You should always follow the stability of your measurement devices. In case the device needs to be adjusted during a recalibration, you should always save the calibration results before As Found and after As Left adjustment.
If you only adjust the instrument and make a new calibration certificate, it will look like the instrument was very stable and there was drift, although that is not the truth. If you send your instrument out for recalibration, make sure you get the calibration results before and after adjustment, if an adjustment was made. Also, make sure you know if it was adjusted. After you acquire a longer stability history of the measurement device, you may start making changes to the calibration period.
If the instrument drifts too much and often fails to meet the tolerance in recalibration, then you naturally need to make the calibration period shorter. Also, if it clearly meets the tolerance limit in every recalibration, without any need for adjustment, you can consider making the calibration period longer. You should have an accepted, written procedure in your quality system for changing calibration periods, and also defined responsibilities.
Typically, if the stability of an instrument looks good in the first recalibration, you should still wait for a few recalibrations before making the period longer. If you plan on making the period longer , the costs for a failed recalibration should be also considered. On the other hand, if a recalibration fails, you should shorten the calibration period immediately.
Naturally, that also depends on how much it fails and how critical it is. If you use the Beamex CMX Calibration Manager software , it will generate you history trend graphics automatically with a push of a button. In the previous chapter, the stability history was discussed as an important consideration. Sometimes you already have previous experience with the stability of the instrument type that you need to set the calibration period for.
Often the same types of instruments have similarities in their stability and long-term drift. So, the past experience of similar measuring instruments should be taken into account.
Similar types of instruments can have similar calibration periods, but this is not always true, as different measurement locations have different criticality, different needs for accuracy and may also have different environmental conditions.
For certain industry measurements, there can be regulatory requirements, based on a standard or regulation, that stipulate the accepted length of the calibration period.
It is difficult to argue with that one. I've heard customers say that it is difficult to change the calibration period as it is written in their quality system. It should, of course, be possible for you to change your quality system if needed. A proper risk analysis should be performed when determining the calibration period of instruments. One thing to consider when deciding on a calibration period of any instrument is the cost and consequences if the calibration fails.
It is to find a good balance between the costs of the calibration program versus the costs of not calibrating enough. If it is the case of a non-critical application and a fail in recalibration is not that important, then it is ok that the calibration fails from time to time.
Sure, you should still adjust the instrument during the calibration to measure it correctly and to have more room for drift before the next recalibration. In the worst case, it may result in a warning letter from a regulatory body like the FDA in the pharmaceutical industry , loss of license to produce a product, negative reputation, loss of customer confidence, physical injury to persons on the job or to those who receive a bad end product and so on.
Also, one really alarming consequence is if you need to recall delivered products from the market because of an error found in calibration. For many industries, this kind of product recall is obviously a very big issue. An erroneous heat treatment can cause very severe consequences. Certainly, pharmaceutical and food industries will also face huge consequences if poor quality products are delivered because of poor calibration or lack of calibration.
Finally, a couple of vital things you should remember with any calibration are traceability and uncertainty. Shortly said, traceability means that all your calibrations measurement instruments must have a valid traceability to relevant national standards. Whenever you make a measurement, you should be aware of the uncertainty related to that measurement. If the traceability and uncertainty are not considered, the measurement does not have much value.
For more detailed information on traceability and uncertainty, please take a look at the below-mentioned blog posts:.
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