Thermometer verification

Hi guys,

I have been racking my brain on whether its inadequate to verify thermometers that are calibrated annually using the ice slurry-boiling point method without necessarily having a reference thermometer. Can someone please shed some light on this for me. 

Hi guys,

 

I have been racking my brain on whether its inadequate to verify thermometers that are calibrated annually using the ice slurry-boiling point method without necessarily having a reference thermometer. Can someone please shed some light on this for me. 

Hi lilian,

It depends on the purpose of yr "verification".

For example, if yr calibration procedure/equipment will subsequently be required/audited to be documentarily traceable to something like NIST, it will probably be inadequate unless you use  an appropriate, internal, reference thermometer (= internal master) or an appropriate external lab.

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Thanks for the reply. The thermometers are calibrated annually by an external facility but for monthly verification I use the ice slurry-boiling point method but without a reference thermometer. 

Thanks for the reply. The thermometers are calibrated annually by an external facility but for monthly verification I use the ice slurry-boiling point method but without a reference thermometer. 

Hi Lilian,

Assuming your external calibration is satisfactorily carried out and appropriately documented  then it generates an internal  master thermometer with a known error at 0degC and 100degC (assuming those temperatures were calibration points). So IMO no particular benefit to yr ice/boiling point comparisons on this thermometer unless you perhaps suspect the calibration has become grossly in error.

(IMEX an externally calibrated thermometer which was externally set to be correct at 0.0degC will seldom give a reading of precisely 0.0 degC in laboratory crushed, melting ice for various possible reasons).