Good day,
I am trying to create a procedure for Intermediate Checking of our Reference Standard.

Based in ISO/IEC 17025:2005 under

5.6.3.3 Intermediate Checks
"Checks needed to maintain confidence in the calibration status of reference, primary, transfer or working standards and reference materials shall be carried out according to defined procedures and schedules."

In my understanding, one main reason for this Intermediate Check is to verify the Reference Standard's drifting if it needs to shorten the calibration interval or other technical reasons. One of our calibration provider (which is ISO/IEC 17025 accredited) told me that the accuracy ratio should be a minimum of 1:2.

My question is this,

"Is it possible to use a micrometer for the Gauge Block Intermediate Checking?"

In my opinion, accuracy ratio is not the basis in the Intermediate Checking but understanding the status or drifting of the equipment to maintain the confidence of the whole calibration process.

Good day,
I am trying to create a procedure for Intermediate Checking of our Reference Standard.

Based in ISO/IEC 17025:2005 under

5.6.3.3 Intermediate Checks
"Checks needed to maintain confidence in the calibration status of reference, primary, transfer or working standards and reference materials shall be carried out according to defined procedures and schedules."

In my understanding, one main reason for this Intermediate Check is to verify the Reference Standard's drifting if it needs to shorten the calibration interval or other technical reasons. One of our calibration provider (which is ISO/IEC 17025 accredited) told me that the accuracy ratio should be a minimum of 1:2.

My question is this,

"Is it possible to use a micrometer for the Gauge Block Intermediate Checking?"

In my opinion, accuracy ratio is not the basis in the Intermediate Checking but understanding the status or drifting of the equipment to maintain the confidence of the whole calibration process.

You could use a micrometer, however the results will not tell you anything of value and in fact will likely be misleading, so it is better not to. The micrometer will NOT give you a 2:1 or 4:1 ratio; rather you will have a 1:4 ratio instead.

The best thing is to send reference standards out for calibration at an accredited lab, get the uncertainty, and use the uncertainty and measured values from the accredited lab to track the gage blocks. Use the same concept for any reference standards you own.

Hope this helps.

Good day,
Thank you for your input. I'm just conducting some evaluation regarding this matter. Although the accuracy ratio is not met by using micrometer, I can still see some deviation in my measurement by using the analog measurement of micrometer and using several measurement readings. One of my analysis is that there is a difference between using the analog and digital display of a micrometer. It's better to use the analog display. As of now, I'm using our CMM to monitor the drifting/performance of the Gauge Block and we send the Gauge Block to Accredited External Calibration Lab annually.

The down side is that if you are seeing a drift using mics to check gage blocks.....I would be more likely to accept the gage blocks.....the mic may drift.....gage blocks, even accounting for temperature variance and so forth.....drift is not usually an issue.....except over a several year period.....

Trust the REFERENCE standards, NOT the working devices.....

Thank you for your the reminder. The purpose of the evaluation that I have just made is to justify some process control in our lab. I do appreciate your inputs.

Thanks:applause::thanx:

Calibration & intermediate checks of equipment are always an issues for labs I guess.

Last audit we have findings like equipment transportation & how do we maintain the calibration of equipment during storage & transportation?