ISO 9001:2000 Calibration Procedures for DMM/Oscilloscopes/Power Supplies

[GrantP]

My organization is attempting to become ISO 9001 certified. We are currently implementing calibration procedures for our test equipment. It’s basically my job to come up with procedures to do this. In the machine shop things are pretty much finished, but the electrical shop is something that I am relatively new to. I would like to know how you calibrate digital multimeters, oscilloscopes, and power supplies. I know that Fluke does offer calibrators for this type of thing, but they are expensive. Are there any other similar products on the market? Also, I would like to know the names of some organizations that perform calibration services for higher frequency oscilloscopes.

I appreciate any help you can give.

Grant Parr

 

[Graeme]

Welcome! Dive in, the water's great!

My organization is attempting to become ISO 9001 certified. ... I would like to know how you calibrate digital multimeters, oscilloscopes, and power supplies. I know that Fluke does offer calibrators for this type of thing, but they are expensive. Are there any other similar products on the market? Also, I would like to know the names of some organizations that perform calibration services for higher frequency oscilloscopes.
Grant Parr

Welcome to the Cove, Grant!

You did not give any indication of the number of items you are talking about. If you have a small electronic calibration workload it may be most cost-effective, at least in the short term, to send the work out so a qualified supplier. In addition to the big national chains (GE Industrial, Sypris, Simco and others) there may be smaller outfits local to you.

If you have a large workload and do NOT have qualified electronic technicians with calibration experience, then consider that all of those organization, plus Agilent and a few others, also provide on-site service.

Calibration standards and other considerations -

• For a small shop with a diverse workload, one of the best standards I have seen is the Fluke (formerly Wavetek) 9100 Universal Calibrator. Fully loaded with all options, it will handle most electronic test equipment - digital multimeters, current clamp meters, oscilloscopes to 650 MHz, digital thermometers and a lot more. The lab I work with has two and they are both more than 80% utilized.
• For power supplies you will need a couple of good digital multimeters, calibrated current shunts, and preferably an electronic load.
• Other types of standards are available from TEGAM. For oscilloscopes, they now manufacture a line of manual calibrators that were discontinued by Tektronix a long time ago. They also make standard resistors (formerly ESI), and RF/microwave measurement systems (formerly Weinschel). If you see listings for standards manufactured by GenRad (or General Radio), look at QuadTech and IET Labs for their successors.
• For ideas on calibration methods and techniques, look at the online papers at all of these manufacturers and other places. Agilent has a very extensive library of application notes -- consider that they used to be Hewlett-Packard before the computer geeks ran off & took the name with them. Agilent also has an online metrology forum that is almost as good as the information here at The Cove but without the real-time discussion capability.
• If your company has or supports a US Government contract, get the information on the program and contract number and sign up for access to the GIDEP database (www.gidep.org). They have most unclassified government calibration procedures available, and many from participating companies as well -- as well as a wealth of other resources.
• Training is essential. Introductory calibration classes are given regularly by Fluke and other companies. Check with your Fluke representative to see if their book Calibration: Philosophy in Practice (published in 1994) is still available - it's worth it if you can get it.
• Some organizations have very good computer-based training available.
• Look at the NCSL International web site and see if it would be worthwhile to join that organization (www.ncsli.org). Their series of reccomended practices, for example, is quite extensive. They also have a list of training resources.
• If you are a member of ASQ (www.asq.org) then also consider the ASQ Measurment Quality Division. Also you may want to look at the new book The Metrology Handbook available from ASQ. Another useful book from ASQ is The Uncertainty of Measurements.
• Search the archives of trade magazines such as Test & Measurement World.

That's all I can think of right now, and besides my carpool is on the way. More later,

 

[GrantP]

Thank you for the information. Our shop is small, about 30 DMM's, and less than 10 oscilloscopes.

 

[Graeme]

Grant,

With a workload that small there really is not enough to keep a calibration technician busy for more than about two or three weeks per year even without any automated systems.

It's a management decision for your company, of course. But if I had my consulting hat on I would suggest looking for a calibration supplier instead of purchasing expensive standards (and maybe hiring an expensive technician) that would be idle most of the time.

I don't know, of course, if there are any qualified suppliers in Newfoundland. But I did do a couple of quick searches on Google.com -- with the usual cautions about the quality of the results:

• The search term "calibration traceable 17025 site:.ca" listed over 30 results, many of which are actually calibration labs.
• The search term "calibration traceable site:.ca" listed over 700 results, many of which are actually calibration labs, spread all over the country from NB to BC.

 

[GrantP]

The idea of purchasing standards would be that someone already in our orgnaization would take time from his regular duties once per year (or 6 months or whatever interval we decide) to calibrate/verify the equipment. Of course, this only works under the assumption that someone in our organization would be able to calibrate the equipment without an extensive amount of training. Verification I'm sure is fairly simple, but adjustments being made to equipment would be a much more difficult matter. If a specially trained calibration technician is required to perform the calibrations, then sending it out for calibration becomes the best choice.

Thank you again, for your advice.

 

[GrantP]

Another question: Under ISO 9001, is it sufficient if my calibration service provider has traceability to national standards? Do they need a specific certification? I assume they will need to supply traceability certificates or some other proof of their conformance.

 

[Graeme]

Another question: Under ISO 9001, is it sufficient if my calibration service provider has traceability to national standards? Do they need a specific certification? I assume they will need to supply traceability certificates or some other proof of their conformance.

ISO 9001:2000 does not specifically require measurment traceability in its text. However, section 7.6 Control of measuring and monitoring devices does point to ISO 10012:2003 Measurement management systems - Requirements for measurement processes and measuring equipent as a guidance document. That standard explicitly states (7.3.2) that all measurement results shall be traceable to SI units of measurement. Note that the measurement management system as defined by 10012 applies to all product-related measurements and measurement processes that that are used to support and demonstrate conformance to measurement requirements.

Definitions:

• SI: International System of Units, commonly known as the modern metric system. The acronym is from the French name.
• Traceability: a property of a measurement result that allows the result to be related to stated references through an unbroken chain of comparisons all of which have stated uncertainties.

Measurement traceability is normally achieved by following a chain of calibration results back to a national metrology institute (NMI) and from there to the SI units. In Canada the national metrology institute is the National Research Council's Institute for National Measurement Standards (INMS); in the USA it is the National Institute of Standards and Technology (NIST).

A certificate from a calibration lab should normally list the specific measurement standards used to calibrate your instrument, and the date each one is next due for calibration. The certificate should also contain a statement attesting to measurement traceability. (section 7.1.4 of 10012) If that lab is audited, then their records will show where the standards were calibrated and what was used for them ... and so on until a some point a relevant standard is calibrated by an NMI.
​

ISO 9001:2000 does not have any specific requirements for an outside calibration activity. There are, of course, the standard considerations of your purchasing process (section 7.4) that would apply to any supplier. The standard also has implied requirements in section 7.6 and by reference to ISO 10012. It would be preferable if the calibration supplier is registered to ISO 9001 or some other quality management standard. Best of all would be a lab that is accredited to ISO/IEC 17025 and which includes the parameters you require within its scope - but that often drives the cost up.

In summary,

• Your product-related measurement results have to be traceable through national standards to the SI; from this it is clear that the calibration results of your instuments also have to show evidence of traceability.
• A calibration lab normally shows traceabilty by a statement attesting to it and by listing the specific measurement standards used with their next due dates.
• Purchasing and supplier clauses of ISO 9001 do not have any certification requirements for suppliers of calibration services. However, a prudent purchaser should certainly consider it.

A final note about measurement traceability: from the definition, it is a property of a measurement result - nothing else. It is not possible for an instrument, certificate or organization to be traceable in this sense. Also, a measurement result can be considered traceable only if the uncertainty of the measurement is also known.

 

[Ryan Wilde]

It's been quite a while since I poked my head in, and I thought that I'd throw in another thought on this thread.

Besides the training issue, you must also consider the cost of calibration of the standard that you use to calibrate the DMMs and Oscilloscope. If you purchase the 9100 with the bells and whistles, you are looking at around $750-1000 per year for standard calibration, which would cover about 80% of outsourcing the actual gauges. When you factor in labor, you will pay more doing it yourself.

Our general rule of thumb for our standards is that if it costs as much to calibrate it than it earns, it's gone.

Ryan

 

[Graeme]

Our general rule of thumb for our standards is that if it costs as much to calibrate it than it earns, it's gone.

Thanks, Ryan. As I am a contractor with my present organization, I don't (can't) get involved in the money decisions ... only actual employees get to see that stuff.

Graeme

 

[clopez]

Hi:
Our lab is trying accreditation under ISO/IEC 17025. In this context, we need to work with international calibration procedures. We have a lot of experience calibrating voltage ac and current ac in recorders and analyzers of energy. However, we have not procedures named before. Somebody can help us with this? Equipment to calibrate are Power Recorder, Toas1000, Memobox.