Calibration of Wall Thermometers
1. Taking a NIST traceable spirit thermometer in the plant, allowing it to equilibrate, and comparing the reading to each wall thermometer at their point to ensure they read the same
2. Taking a calibrated (ice bath) spirit thermometer and doing the same
3. Purchasing NIST traceable wall thermometers and sending them out for annual calibration
... just wanting to make sure I'm covering this properly
Are there any other methods for calibration of wall thermometers aside from:
1. Taking a NIST traceable spirit thermometer in the plant, allowing it to equilibrate, and comparing the reading to each wall thermometer at their point to ensure they read the same
2. Taking a calibrated (ice bath) spirit thermometer and doing the same
3. Purchasing NIST traceable wall thermometers and sending them out for annual calibration
... just wanting to make sure I'm covering this properly
Dear Marshenko,
The basic method would be similar but I cannot see any objection to replacing the (checking) NIST spirit thermometer by a traceably calibrated master thermocouple unit, or a self-generated sub-master unit. Analogous to one method for calibration / utilisation of balances. Possible advantages are portability and ease of calibration at any chosen temperature close to a typical working condition. Calibration is easiest to implement with a zero-able thermocouple.
Or perhaps your particular environment necessitates the use of spirit-based instrumentation only ?
(or maybe a question of accessibility?)
Rgds / Charles.C
Can anyone please help me with sop for wall thermometer calibration?
Assuming that the wall thermometers you are referring to are not used to monitor CCP temperatures you can simply verify their accuracy once per year by hanging a calibrated digital hand held thermometer beside the wall thermometer and leave it until it is displaying the ambient room temp. Compare the two, If the wall thermometer is more than one degree different than the calibrated thermometer then replace it. That simple. We use digital refrigeration thermometers that we seal with a rubberized spray to keep the moisture out. They are solar powered and the display is in tenths of a degree. NIST certification should not be required for any room not associated with a CCP. This what we do and this procedure did not raise any eyebrows during our last BRC audit as the food safety risk for a thermometer being out one or two degrees is very low.
Hi handyandy,
I would have expected that a routine wall thermometer at ca 60-90degF was almost guaranteed to be more than 1degF out? .
I guess it all depends on how accurately you wish to monitor the room temperature and the environment, eg limited by draughts ?
@pbedi - For what purpose ? what degree of accuracy do you require ? to satisfy what standard ?
its is for just monthly verification to meet SQF requirements.
its is for just monthly verification to meet SQF requirements.
Can you inform the paragraph in SQF standard ? eg to verify what ?
(the simple answer is likely given in Post 1, No.1) - something like -
(a) you buy a ref. thermometer
(b) you attach it to the wall thermometer
(c) you wait for equilibriation
(d) you record the 2 readings and the difference
(e) you accept/reject the wall thermometer if the difference is outside yr limit (which may depend on the usage)