I would like to have an opinion regarding the test/calibration of test equipment that are used in preventive maintenance of medical equipment.
Let's say for example I am doing PPM on a patient monitor. A suggestion of our ISO consultant is that instead of sending test equipment yearly for calibration, we should set aside a "reference monitor" as the basis for calibration.This reference monitor will be unused say for 3 years.
Logically there is a sense to this idea but I am not very comfortable with it.
My question is-if an equipment is unused(i.e. kept in the cabinet) would it be right to assume that the calibration can be extended to more than 1 year? Also can said equipment be used for reference?

My experience with using 'secondary standards' as calibrated references is that you must prove them first. That is you need to select several items and repeatably check them over a period of time and select the one with the best stability. you then need to back this one piece of equipment up with another stable reference to be used when you suspect that the first of giving an unexpected result. Even then you can not be absoluteley sure of your calibration. I would only normally recommend doing this when direct calibration against standards is not possible.

Strange, our consultant said that we should not use non certified equipment for "Calibration", however we can use some other types of equipment for Go/No Go type checks or for general indication.

We do use some devices for "indication / reference only" that we could check against one of our calibrated devices.

As an example, we do have some calibrated multimeters, however the majority are for reference only (to save costs).

I would discourage against general non-calibration of test equipment, particularly if you are calibrating against it, however sense and logic allows you to single out individual devices that may be markered as "reference only".

Regards
Joe

IS it then a strict rule that test equipment used for calibration should be factory calibrated yearly?
Of course there are ways of calibrating it ourselves but then there is again an issue of "traceability". The standards that we will be using are subject to calibration too.

Yep, during quality audits of our dept, the assessor will pick up pick up various pieces of test equipment, if not marked as reference only she will request the paperwork to show that it has been calibrated to national standards.

It has been quite a flesh giver over the past couple of years, but finally we can put it to bed as it is all fully documented now. Once they know you have corrected your ways they wont ask so often.

.... but whats next

If you want to calibrate test equipment (like multimeters) you can buy a calibration standard (which you must then have calibrated regularly) and check all your meters against it.

Unless you've got a lot of meters it's cheaper to just send them off to a local calibration lab !

As for checking the calibration of medical equipment, I wouldn't trust a piece of equipment which had been sat in a cupboard for a couple of years to be an accurate "standard" to do comparrisons against. That also sounds like a very expensive way of achieving the desired result - or not, as the case may be !

Just thought i would revive, and slightly extend this topic.

As the general consensus appears to be that we do send test equipment away for calibration, and require the provision of the all important certificates traceable to "national standards" (obviously only talking about the UK here, so how this issue is dealt with in the majority of the world would also be interesting to hear).

Which companies do you all find provide an efficient / reliable and of course "competetively priced" service.

Hopefully, we might learn about some gems out there that could save us all money!

The general consensus amongst those funded by the taxpayer, perhaps?

Those who dwell in the Real World have to minimise expenses by, for example, applying a bit of what we might call nous.

For example:- although we know that it's working just fine, and even suspect that it's well within spec, test equipment item No.1 gets sent away to gain its (expensive) seal of approval.

When at long last we see it again (after being bounced - and, most likely, chucked and kicked - about in various vans), we assume that it's now "perfect", especially as it now carries that all-important feature ... a piece of paper.

But (cunning folk that we are), we now compare (and, if necessary - but it seemingly never is - re-calibrate ... as in "adjust") test equipment No.2 ... No.100 against No.1. Traceable to "national standards"? Yes, why not (just as long as it's documented ... as in "noted, signed and dated in the test equipment log book")?

You are fishing for gems? OK, here's the first one:- you just need to be thoughtful about which bits of test kit you select for "sending away". Send the one(s) with "all the features". Whilst also bearing in mind that some things matter more than others. For instance, what sort of tolerance is good enough on a multi-meter? Or, for that matter an electrical safety tester?

And here's another:- check all your test kit yourself, then only send away the ones that fail that most stringent of the Laws of Physics. You know, the one attributed (quite rightly) to Herr Georg Ohm.

Joe has already mentioned "Indication - for Reference Only", but I would extend this even further by suggesting that such instruments (if you know them, and feel confident about using them) are entirely adequate for the vast amount of testing (checking, fault finding) work carried out in the workshop.

So there's the final "gem":- get some suitable stickers made!

Unless, of course, you work for the NHS ... when you might as well send away the whole lot, and then let them sit prettily on the shelf for yet another year!

Are you sure - or is it a case of maximising profit....

Come Geoff give the NHS workers a day off from your vitriol. This is a valid question about people trying to do the right thing.
My world is real - trust me!

Yes, it's a valid enough question.

So where are the (your) valid answers?