Setting calibration intervals is probably the most important decision to be made by those personnel with responsibility for the calibration system; the length of interval will influence the effectiveness of the calibration operations, and will have a considerable effect on the cost of the calibration process.
When I ask people about the sources of information used to make decisions on their calibration intervals, I get a variety of answers, including some which must be seriously questioned as to their validity and usefulness, such as:
“Our calibration vendor puts a sticker on the instrument with the next due calibration date, and we go by that”, or
“The instrument manufacturer calibrates for us, and we go on their recommendation”, or
“The auditor has pushed us to increase the interval”.
I am not saying you should ignore these sources of advice. However, with the possible and rare exception of the manufacturer of very specialised and unique measuring instruments, these external agencies are not in any position to advise you, and especially not to dictate to you, on your calibration intervals.
The intervals should be based on internal sources of information such as calibration histories, frequency and type of use of the instrument, the technical experience of your own company personnel, etc. This information is not generally available to the external agencies mentioned above, so they are not in a position to specify your calibration intervals.
Learn more about the setting of calibration intervals by attending our Calibration training course. The next scheduled date is 12th March in Dublin.