7 replies to this topic

[Skye]

Can anyone tell me if there is a standard method for calibrating non-contact infrared thermometers, as with probe thermometer checks in iced and boiling water?

Many thanks
Skye

[shea quay]

There is a standard method, but unfortunately not involving steam and ice.

I took a sample of one of these years back for taking the temperature of cooked sliced meats. I couldn't justify them from a food safety perspective (they were used for a critical control point, as the sliced meat was too thin to take an internal temperature). The in-house calibration suggested by the supplier involved a specialised hotplate for reasons that now escape me (something to do with the interaction between heat and different metals?). I would advise you to avoid using these type of thermometers at all costs, as they do tend to drift also. We ended up threading a thermocouple through a syringe needle. Created a bit of extra paperwork, wasn't perfect I agree, but at least we could carry out regular internal calibrations.

[KTD]

Some lab supply companies (VWR Scientific) offer a 'black body' magnetic sheet. The sheet is placed on a large metal surface away from strong environmental tepmerature fluctuations (file cabinet in the office corner) and allowed to equilibrate. You then 'shoot' the sheet to get a temperature. Some sheets have strip thermometers attached - otherwise, check calibration with a calibration verified thermocouple utilizing a flat surface probe and use it to determine the sheet temperature. Obvious potential for increased measurement errors, but best I have seen so far.

[Charles.C]

Can anyone tell me if there is a standard method for calibrating non-contact infrared thermometers, as with probe thermometer checks in iced and boiling water?

Many thanks
Skye

Dear Skye,

There is also a longish thread (this year) here which contains considerable detail on the application / limitations of ir units submitted by an (apparent) expert on the subject. Maybe try a little searching.

Rgds / Charles.C

[GMO]

I have seen a calibration machine where the reference probe is placed into a hole and the test probe placed into another hole to compare but to calibrate the IR probe, the cover is removed to reveal a hotplate which is meant to be at the same temperature as the probe in the hole. I'm not sure I believe it and I don't believe IR thermometers are ever that accurate but it seemed as good a method as any.

[QLD]

I have seen a calibration machine where the reference probe is placed into a hole and the test probe placed into another hole to compare but to calibrate the IR probe, the cover is removed to reveal a hotplate which is meant to be at the same temperature as the probe in the hole. I'm not sure I believe it and I don't believe IR thermometers are ever that accurate but it seemed as good a method as any.

Sounds like the same method but we used one of these and compared against a reference probe : http://www.comarkins...?product_id=214

[Dr Vu]

My take
IR thermometer... Throw out old one and buy a new one once the calibration certificate expires; for verification (daily usage) you can use any surface by comparing with a standard calibrated thermometer( usually the IR i gave a plus/mnus 3 deg C)

No auditor questioned my simple methodology..

[Charles.C]

Dear vulindlela,

No auditor questioned my simple methodology.

They were probably overwhelmed by yr budgetary tolerance.

Rgds / Charles.C