Definition of Calibration Frequency - Dispute during Audit

[Brian C]

Does the term calibration frequency mean the period of time something is in calibration or is it the ongoing "required" periods by which you must calibrate? If our equipment has a one year calibration frequency and it is stored away and during the storage period its calibration expires. At the moment it expires (still in storage) is this an audit finding because we have failed to follow our own determined calibration frequency?

Additional information; There is no record showing we stored it away. It was not found in use or on a workbench by the auditor. We had removed it from storage and sent it in for calibration so we could use it again. A gap was created between the old calibration period and the new one. The auditor looks at the two calibration certificates and notes the gap between the two and assumes we must have been using the equipment out of calibration but there is no evidence of usage. Since there is no evidence of usage he then determines that we still failed to calibrate at our on determined annual interval and quotes ISO 7.6 as evidence to that fact.

In ISO 7.6 Control of monitoring and measuring devices section a) states; be calibrated or verified at specified intervals, or prior to use, against measurement standards traceable to international or national measurement standards; where no such standards exist, the basis used for calibration or verification shall be recorded;

My contention is that the calibration interval is the period of time "we" determine that the equipment calibration is likely to remain stable. (one year in our case) If the calibration period ends and the equipment becomes out of cal, but in storage we would simply be required to calibrate it again prior to use. The auditors contention was that when it expired in storage, regardless of usage we were out of compliance since we could not show evidence that it had been moved to storage and we had failed to follow our own determined interval of calibration of one year.

 

[howste]

Hi Brian, welcome to The Cove!

The calibration frequency is what your organization determines it to be. ISO 9001 uses the term "planned intervals" to describe this, and your organization is the one that determines the plan. If your plan (procedure, work instruction, calibration software, etc.) says it will be calibrated annually regardless of use, then it's a nonconformity. If your plan gives you more flexibility then it may not be. What does your plan say?

Realistically speaking though, your documentation shouldn't "paint you into a corner." If it requires you to do something that doesn't make sense, then change it to make sense. ISO 9001 also says in that paragraph "Where necessary to ensure valid results..." Don't say you'll do something that isn't necessary.

 

[BradM]

The calibration frequency, IMHO, is a nominal approach to managing your calibration program. Saying, if your frequency is one year, then it's going to be very difficult to hit exactly 365 days. It's more of "the last calibration was performed in March; so next March it needs to be sent in again"; if 1 year is your interval. Otherwise, one can run in circles to meet exactly matching the days. Do you pick the date it went in? The date on the calibration certificate? The date it was put back into use? and so on. That's why I suggest having your calibration interval nominal.

Now... I would also suggest you be sure annual is proper for your entire program. Based on your calibration data, it might be too frequent; or more realistically, not frequent enough. Let your data (and your risk) help you determine your frequency.

My contention is that the calibration interval is the period of time "we" determine that the equipment calibration is likely to remain stable. (one year in our case) If the calibration period ends and the equipment becomes out of cal, but in storage we would simply be required to calibrate it again prior to use.

I agree. The more important question is not what the calibration interval is, but is the one you have effective. If you have a large number of failures on your current interval, then you probably need to tighten the interval.

The auditors contention was that when it expired in storage, regardless of usage we were out of compliance since we could not show evidence that it had been moved to storage and we had failed to follow our own determined interval of calibration of one year.

Part of this is a reasonable opportunity for improvement, and part of it is... well... less reasonable, IMHO. When an instrument is past due for calibration, it needs to be segregated where it's clear no one can use it. Was storage locked up? Could someone access it and use it? If yes, then something to consider improving. If no, then there is no way it could have been used. Thus, not an issue.

It would be a tremendous waste of time and money running 100 mph just to assure a calibration is performed within a 365 day window. There is no value in that. Your value is assuring that you manage your program effectively. Do make sure that you have made demonstrated assurances that no one can use a past due calibration instrument. Just make sure the language in your documentation reflects that the calibration interval is 1 year; and not that calibration will be performed within 1 year. Make sense? They are two different things.

 

[Hershal]

Frequency refers to period of calibration action. Increased frequency means shorter time of the item being within calibration dates.

As for storage, I would suggest that if the item goes into storage, place a "Calibrate before use" sticker on it.

 

[Jeff Frost]

As I follow the discussion to this point it appears that the following has occurred with your 7.6 process.

1) Your process does not address extension of calibration based on review of records of calibration/verification or when removing calibration items from ready to use storage.
2) Your records do not reflect that the measurement devise was calibrated and then placed in storage and then removed for use thus extending the calibration beyond 1 year.
3) Your current system may address 7.6 requirements but it is not a complete system.

I have said this in other calibration posts on the Cove but the requirements in ISO 9001 Clause 7.6 is just a framework of a calibration system but you need to fill in the frame by adding the requirements from ISO 10012, "Measurement management systems – Requirements for measurement processes and measuring equipment" and then plug the remaining holes with ANSI/NCSL Z540.3 "Requirements for the Calibration of Measuring and Test Equipment". By using ISO 9001, ISO 10012 and Z540.3 together you will have a fully functioning calibration process that meets the ISO 9001 standard and customer requirements.

 

[AndyN]

Your auditor is arguing based on a partial knowledge of the issue. What should have been looked at is the calibration data - as found and as left. Had that been brought into the audit, the whole discussion about dates goes away. Some items of equipment are very stable but the auditor didn't know enough to look into that - and I'd suggest that, next time, you pull up the data and nip that line of inquiry in the bud...

 

[Al Dyer]

Does the term calibration frequency mean the period of time something is in calibration or is it the ongoing "required" periods by which you must calibrate?

(me)-----The latter, as determined by you.

If our equipment has a one year calibration frequency and it is stored away and during the storage period its calibration expires. At the moment it expires (still in storage) is this an audit finding because we have failed to follow our own determined calibration frequency?

(me)-----Yes, because you have determined the frequency of calibration.


Additional information; There is no record showing we stored it away.

(Me)-----Why?

It was not found in use or on a workbench by the auditor. We had removed it from storage and sent it in for calibration so we could use it again.

(Me)-----Therefore you have verifiable system that allows you to remove and reintroduce it to use. Is there a reason an auditor should find it in or out of use and have a concern?

A gap was created between the old calibration period and the new one.

(Me)-----Could you further explain why there would be a gap?

The auditor looks at the two calibration certificates and notes the gap between the two and assumes we must have been using the equipment out of calibration but there is no evidence of usage.

(Me)-----In your process you state the calibration requirements. There is no reason for a N/C because you exceed your stated minimums. Time to take it up a notch to the auditors "boss". Make sure the language in documentation is acceptable.

Since there is no evidence of usage he then determines that we still failed to calibrate at our on determined annual interval and quotes ISO 7.6 as evidence to that fact.

(Me)-----Always know that we are the customers, pay the bills, and requested that a service be performed. As quality professionals we must always stand up for ourselves as well as our employers.

Great question Brian!!!

Al...

 

[PaulGr]

Good discussion!

One thing I miss in the discussion is that calibration is not only intended to ensure future measurements are accurate, but also to validate previous measurements (See ISO9001, 7.6, below bullet e). An equipment needing readjusting as part of the calibration triggers correction, corrective and or preventive action.

Cheers, Paul

 

[Jim Wynne]

Good discussion!

One thing I miss in the discussion is that calibration is not only intended to ensure future measurements are accurate, but also to validate previous measurements (See ISO9001, 7.6, below bullet e). An equipment needing readjusting as part of the calibration triggers correction, corrective and or preventive action.

Cheers, Paul

It doesn't necessarily trigger any of those things. What's required is for the organization to "...assess and record the validity of the previous measurement results when the equipment is found to not conform to requirements." If the the device is found to be nonconforming, "The organization shall take appropriate action on the equipment and any product affected."

If the assessment reveals that product previously measured wasn't affected by the out-of-tolerance measuring device, no further action is required beyond recording the results of the assessment.

 

[BradM]

Good discussion!

One thing I miss in the discussion is that calibration is not only intended to ensure future measurements are accurate, but also to validate previous measurements (See ISO9001, 7.6, below bullet e). An equipment needing readjusting as part of the calibration triggers correction, corrective and or preventive action.

Cheers, Paul

Just to kind of add on to what Jim posted.

An equipment needing readjusting as part of the calibration

All instruments will have some error. I'm not sure I have ever seen a "perfect" instrument reading. I have seen gauges (particularly analog pressure gauges) that may not have adequate resolution to display the error. Those instruments with adequate resolution will always display some error. The deal is, the error is most of the time insignificant to the task at hand.

Some calibration providers always adjust the instrument for maximum accuracy; some only adjust when it reaches a certain percent or whatever.

Hence the reason to have a stated tolerance for a calibration. As long as the instrument's error is within that tolerance, it would be considered to be operating normally and require no further investigation.

Only when it exceeds tolerance is an impact investigation required.