Thermometers
Error limits for thermometers

Error limits for thermometers

The following error limits are according to "Eichordnung EO 14-1", the German Federal Weights and Measures Regulations.

For thermometers calibrated for total immersion containing non-wetting thermometric liquid (e.g., mercury and mercury-thallium alloy) and for thermometers containing wetting thermometric liquid (e.g., toluene, pentane and petroleum).

 

Official error limits for thermometers containing non-wetting thermometric liquids, for the subdivisions:
Plage de température de ° C / à
  Temperature range
  from °C / to °C		 0.05 °C 0.1 °C 0.2 °C 0.5 °C 1 °C 2 °C 5 °C
-58 / -10 -  ± 0.3 ± 0.4 ± 0.5 ± 1 ± 2 ± 5
-10 / 110 ± 0.1 ± 0.2 ± 0.3 ± 0.5 ± 1 ± 2 ± 5
110 / 210 -  -  ± 0.4 ± 0.5 ± 1 ± 2 ± 5
210 / 410 -  -  -  ± 1 ± 2 ± 2 ± 5
410 / 610 -  -  -  -  ± 3 ± 4 ± 5
Official error limits for thermometers containing wetting thermometric liquids, for the subdivisions:
Plage de température de ° C / à
  Temperature range
  from °C / to °C		                                0.5 °C 1 °C 2 °C 5 °C
-200 / -110       - ± 3 ± 4 ± 5
-110 / -10       ± 1 ± 2 ± 4 ± 5
 -10 / 110       ± 1 ± 2 ± 3 ± 5
110 / 210       - ± 3 ± 4 ± 5

 

 

Calibration / Temperature correction (approximation)

Unless marked otherwise, thermometers are calibrated "for total immersion". Hence that the meniscus of the mercury column is level with the surface of the liquid being measured. If part of the mercury column is visible above the liquid surface, a correction may be necessary.

Equation for correction:

tk = t + (t-t')n/6250

Example:
Temp. reading:         t   = 160 °C
Immersion point:      tx = 85 °C

Mean temp. of emerging
mercury column:       t' = 32 °C

Length of emerging
column in °C
(on scale):              n = 160-85 = 75

Corrected temp.:   tk = 161.5 °C