Recording chart vs. thermometer

[tbostock]

I have always understood that when we take temperatures of a refrigerator, all temps (thermometer top shelf, thermometer bottom shelf, chart recorder and digital readout) must agree within 1 degree C, but I am unable to find a regulation for that...is it FDA? Or am I thinking of a certified thermometer matching another thermometer within 1 degree?

And if they do not agree, the thermometer (that is calibrated annually against a NIST certified thermometer) is the "tiebreaker", correct? That is, the recording chart and/or digital reading should be changed to reflect the thermometer reading? Although it takes longer for the thermometer to react to sudden changes in temp...

[Mary**]

:)I was recently insoected by the FDA (BAD experience). She wanted to know where I got my info on how close the recorder had to be to the thermometer. I called Helmer and they said it is up to the customer to set their ranges. I use 2 C for the refrigerators and platelet incubator and 5 C for the plasma freezer. She did not site that issue.

[L106]

I had a similar experience as Mary** did. Several years ago an inspector notice that we had a difficult time getting the freezer thermometer and chart recorder to match. She told us that it was up to us to decide (and specify in our Procedure Manual) what ranges are acceptable to us. We use +/- 1C for the refrigerators and plt incubator and +/-5 C for the plasma freezer (and all future inspectors have been satisfied.)

Edited July 15, 2009 by L106
Added punctuation

[Brenda K Hutson]

See the 15th Edition of the Technical Manual; page 198 (Thermometers). "The temperature of the thermometer should be compared periodically with the temperature on the recording chart. If the two do not agree within 2C, both should be checked against a certified thermometer."

Brenda Hutson, CLS(ASCP)SBB

[BBK710]

See the 15th Edition of the Technical Manual; page 198 (Thermometers). "The temperature of the thermometer should be compared periodically with the temperature on the recording chart. If the two do not agree within 2C, both should be checked against a certified thermometer."

Brenda Hutson, CLS(ASCP)SBB

Interesting. I can't find that in the 16th Edition. There are major changes in that chapter and it is more vague than the 15th edition. It just says to do daily checks of temperatures and document diviatios on recording charts. There is no mention of comparison of thermometers to recording devices.

[tbostock]

I can't find it in the 16th edition either, hence my dilemma. So for now, I will define it in my policy (±2° for refrigerators and platelet incubators and ±5°C for freezers). Thanks all for your help.

[clmergen]

They may have taken it out due to the proliferation of remote monitoring systems. The recording device is just a computer that records what the probe reads, its an all in one system.

The intent of checking chart and thermometer is to ensure your recording device is recording correct temperatures so I would expect that an acceptable difference would be defined by your faciltiy, but would have to be reasonable.

[eric1980]

They may have taken it out due to the proliferation of remote monitoring systems. The recording device is just a computer that records what the probe reads, its an all in one system.

The intent of checking chart and thermometer is to ensure your recording device is recording correct temperatures so I would expect that an acceptable difference would be defined by your faciltiy, but would have to be reasonable.

As I read the thread, questions lingers in my mind, until I read this post.

So what if the thermometers don't agree, but both readings are still within the acceptable range. And what is the basis of using +/-1C or +/-2C to be acceptable?

The equipment probe is actually situated against the inside back wall of the fridge/freezer and the thermometer couldn't get any where close to it. So it will be puzzling to me if they actually give me the same reading.

So I guess we just have to state a reasonable difference and accept it as it is...

[RR1]

Generally thermometer calibration should be +/- 0.5'C against a UKAS in U.K (or NIST in U.S I suppose) calibrated thermometer- this is the primary calibration. If you use this thermometer to calibrate others against, then the accuracy changes to +/- 1'C.

Basically there is a higher error in the reading accuracy the further removed you are from the primary calibrated instrument.

[Carl Klass]

Transport-r Inc is a company that has addressed the temperature protection of transfusion bloods and other blood products (FFP/Plt) during the period between release of the product from the Blood Bank until the product transfusion has begun at the patient unit (Floor, OR and remote locations). They offer an Infra Red thermometer that has been specially calibrated at the critical ranges required by AABB and FDA. Check their website: Bloodtransport.us