Calibrating a Thermometer for use in Cold Rooms - ISO 9001 Clause 7.6

[DAWELAH]

Dear Members,‎

Hi,‎

How do I ensure that requirement 7.6 is implemented in cold rooms? ‎

I use external thermometers to verify temperature taken from cold room readings. Should I go through planned calibration process to ensure that thermometer is giving accurate results? ‎Keeping in mind that thermometer costs $ 20 and calibration fee is around $90 ‎
‎ ‎
Thanks ‎

 

[somashekar]

Re: Calibrating a thermometer for use in cold rooms.

Dear Members,‎

Hi,‎

How do I ensure that requirement 7.6 is implemented in cold rooms? ‎

I use external thermometers to verify temperature taken from cold room readings. Should I go ‎throw planed calibration process to ensure that thermometer is giving accurate results? ‎Keeping in mind that thermometer costs $ 20 and calibration fee is around $90 ‎
‎ ‎
Thanks ‎

Cold rooms (2 - 6 'C) are mostly the walk in type and you use this for storage of your temperature sensitive materials (correct me)
You calibrate the controller and check the inside temperature at areas where you store your materials. I guess you have an internal procedure to do this calibration of cold room. You must off course have a valid calibration for your thermometer before you do this.
I do not know much about your calbration costs, however this costs me around $20 here. Irrespective of the costs you have to use a valid instrument to implement your calibration procedure with its traceability. Remember that this is your secondary master instrument traceable to your calibration agency primary master. we use here an Extech 421501.

 

[somerqc]

Forgive me if the needs of 17025 prevent this (i.e. they won't accept it), but, in a former life we simply boiled water and stuck a thermometer in it to verify it (NOTE: Boiling water is 212F or 100C - or it becomes steam).

If it didn't read within specification (we had +/- .2 degrees C), we replaced it with a new one.

John

 

[Wes Bucey]

FWIW:
I have seen some operations (where temperature maintenance is critical) move up to recording thermometers which maintain a permanent record of readings throughout the day, often coupled with an alarm to signal nonconforming temperature rise or fall beyond specified parameters. Such recording thermometers do need periodic professional checking to determine they are in calibration. Exactly who performs and how that checking proceeds (including frequency) may be matter of discussion between thermometer manufacturer and historical record. Some calibrate as frequently as monthly, others annually, all according to a FMEA (Failure Mode & Effects Analysis) based on how severely a nonconforming temperature may affect the product and experience with a thermometer remaining in or straying from calibration.

 

[BradM]

Sorry I did not reply earlier. I was having thread issues.

Calibration is a service. Sometimes services (especially good ones) are not cheap. Sometimes it costs more to calibrate an item than it's worth. But you need to have confidence in the device.

I think you need to calibrate the thermometers prior to use, and prior to disposal. After all... what if the thermometer drifted out prior to disposition? You would have issues, and you would not even know.

I would be much more attuned to getting good calibration information on the thermometers, and extending the calibration recall as far as you can. You might even consider setting up an inter comparison system. Track the variance of your thermometers; after you get some history and data, you can extend the period so you can save money.

As far as ice and boiling water, it sure beats nothing. However, my experience is that you miss the cardinal points that you are interested in. Too, there is a lot of variance due to probe location, heat source, uniformity, etc. when using boiling water. A properly build ice bath is a good standard, assuming it is constructed properly.

As far as needing calibration, of course, this is coming from a calibration guy. If the correct temperature reading in important or relevant, then it should be calibrated.

 

[step30044]

As far as ice and boiling water, it sure beats nothing. However, my experience is that you miss the cardinal points that you are interested in. Too, there is a lot of variance due to probe location, heat source, uniformity, etc. when using boiling water. A properly build ice bath is a good standard, assuming it is constructed properly.

I would consider this a verification not a calibration. I would also suspect with a $20 thermometer you would want data specific to your process tolerances not data on the extremes. Brad you make a good point on the construction of the ice bath, you would be surprised at how many people dont understand how to create a proper ice bath.

 

[BradM]

I would consider this a verification not a calibration. I would also suspect with a $20 thermometer you would want data specific to your process tolerances not data on the extremes. Brad you make a good point on the construction of the ice bath, you would be surprised at how many people don't understand how to create a proper ice bath.

Good post; agreed.

There is an attachment here at the Cove about how to build a proper ice bath, FWIW.

 

[harry]

Old story but need to repeat - what is the tolerance and what is the risk involved?

Many requirements relating to temperature in the food industry (especially storage) are guided by rules of thumb and +/- 1 to 2 degrees are often acceptable. That being the case, an ice bath not to technical details but with plenty of ice and enough water would normally be accurate up to +/- 1/2 to 1 degree and deemed good enough for general usage. The same goes to those portable thermometer if used for verification purpose.

 

[howste]

you can put it in the room first to try whether it will work~

I don't see how this answers a question about calibration of the device.