Kanomax hand held Laser Particle Counter Calibration

I have a Kanomax hand held laser particle counter. The manufacturer recommends a standard 1 year calibration interval for this device. My company only uses this device 4 times a year. Im trying to decide whether it is acceptable to increase the calibration period to 2 years.

I contacted the manufacturer and asked how they came up with a one year interval. they provided me no information (they said that it was based on some engineering spec, and that it is an industry standard, yadda yadda...). I asked whether the particular model is known to deviate from calibration, and they told me (as expected) that it depends on the specific unit. they said that have no problem setting the calibration period to more than one year if the customer wants it.

So now I need to decide whether it is proper for me to justify an increased calibration interval. basically, I have no data showing that my particular unit has a tendency to stay in or deviate from calibration over either 1 or 2 year periods. on the other hand, the device is stored well, hardly used, does not include batteries or other things that are highly likely to damage the unit. and most importantly, our regular particle count loads have given us a lot of margin for error such that, if our particle counter is deviating form perfect accuracy, it is still unlikely to put our production at risk.

so, question, is it reasonable for me to extend the calibration period? or does the lack of data mean i have to keep it at the factory recommendation?

Factory recommendations for a calibration typically mean little. They have no idea how a customer will use it, under what conditions or such. A one year calibration cycle is a "standard" recommendation from the makers of most measurement equipment.

Calibration frequency should be based upon use, criticality of the measurement and results of past calibrations (specifically whether or not it required adjustment, and if so how much).

It should have been calibrated when you received it - You should have that calibration certificate as a baseline. If you have had it calibrated since then and it did not need adjustment (or the adjustment was minimal) extend the calibration to 1.5 or 2 years (assuming a current cycle of yearly). If you haven't had it calibrated since you received it, get it calibrated (assuming a year in use is near) and see how much, if any, it was adjusted.

Thanks Marc.

Would you be able to provide a reference or two on that? Some authority I can cite?

I don't have a specific reference. You might want to read through some the calibration frequency threads here and I think you'll find what I wrote is relatively standard. I got my first introduction to calibration requirements back in the 1980's in DoD work and I've been involved is various calibration aspects over the years.

I could cite examples, though. One would be a micrometer used on the production floor in a machine shop which is used 50 times daily. The measurement is a precision measurement such as a critical dimension. Over time it will wear, among other things. It may be dropped. On the other hand would be a micrometer used in an inspection lab which is used maybe twice a day. This is an example of "use" being a factor. One would expect the on on the floor to require more frequent calibration. But then again - If both are routinely calibrated and need little or no adjustment the "use" factor (both where it is used as well as how often) may not be an issue.

The bottom line is when you buy a measurement instrument it is typically calibrated at a certain interval. The important thing is whether or not when it goes to calibration whether or not it has to be adjusted or not. As the measurement instrument is something like a micrometer it will be subject to wear. That is why you look at calibration records for that measurement device over time. In the beginning the adjustment should be small or none. But over time, with wear, adjustment will tend to increase. You reach a point where you can shorten the calibration frequency to account for the need to adjustment, but at some time it will simply be too worn out to use.

Of course, there are different types of measurement equipment. Usually electronic equipment is more stable as it isn't subject to wear (or at least most aren't). I have a Fluke 77 multimeter I bought in 1984 (or around then). Last time I had it calibrated was in the mid 1990's. No adjustment needed. Since it's my personal meter and I don't use it often these days, and what I use it for isn't critical, but my bet is it would pass a calibration with little or no adjustment.

At this point I'll ask that someone else here who is into calibration add to my diatribe. What I have said is my understanding but someone who specializes in calibration may point out that I am wrong.

Check this discussion: Adjustment of Calibration Intervals (Calibration Frequency)

I have a similar situation where the manufacturer recommends a calibration frequency and the usage does not warrant a yearly need for calibration. My question is how do you reflect that information in the form of a record? Currently my record will "expire" soon, do i create a calibration extension form? Please help!

You do not need to follow the "recommended" calibration interval. Good practice is to adjust your calibration interval based on the reliability of the instrument.

What I would suggest is you need to review the calibration history of the unit. How many in tolerance calibrations, have there been any out of tolerances, repair / reliability issues, history of similar units, etc. You can use this data to justify extending a calibration interval (and withstand audit questions).

Another factor to consider is product risk due to an out of tolerance. If this particle counter is used in an area where product can be compromised due to contaminates in the air that might not be properly detected by an out of tolerance counter you may purposely keep a lower calibration cycle to avoid product recall issues.