JJF 1409-2013 Calibration Specification for the Surface Thermometers
1 Scope
This specification is applicable to the calibration of surface thermometers with thermocouples as sensing elements in the temperature range from room temperature to 400℃. Calibration of other types of surface thermometers may refer to this specification.
2 Normative references
JJG 617-1996 Verification regulation of digital temperature indicators and controllers
GB/T 13639 Digital indicators with analogue input for use in industrial-process measurement and control systems
For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
3 General
A surface thermometer is an instrument used to measure the temperature of a solid surface, which is composed of a temperature sensor and a digital temperature indicator. The principle of temperature measurement is that the temperature sensing element of surface thermometer temperature sensor is pressed tightly on the surface of measured object, and the surface temperature of measured object is displayed by the indicating instrument. The temperature sensing element is a surface thermocouple, and the indicating instrument generally has the function of automatic temperature compensation at the reference end of the thermocouple.
4 Metrological characteristics
4.1 Appearance
4.1.1 The shape and structure of the surface thermometer shall be intact, and there shall be no defects affecting the measurement accuracy.
4.1.2 The plug-in polarity of the temperature sensor shall be correct, the contact shall be good, and the material of plug-in shall be the same as that of temperature sensing element.
4.1.3 Switch on the power supply of surface thermometer, and the indicating instruments shall display normal.
4.2 Indication error
The difference between the indicating value of surface thermometer and the actual temperature is the indication error of surface thermometer.
5 Calibration conditions
5.1 Ambient conditions
5.1.1 Ambient temperature: (23 ± 5)℃, the relative humidity shall not be greater than 85%, or comply with the ambient conditions specified for calibration instruments and equipment.
5.1.2 During the calibration process, the ambient temperature fluctuation shall not exceed 0.5℃. There shall be no environmental factors affecting the measurement results in the calibration laboratory.
5.2 Measurement standard and other equipment
5.2.1 Standard instrument
Foreword II 1 Scope 3 General 4 Metrological characteristics 4.1 Appearance 4.2 Indication error 5 Calibration conditions 5.1 Ambient conditions 5.2 Measurement standard and other equipment 6 Calibration items and methods 6.1 Calibration items 6.2 Calibration methods 7 Expression of calibration results 8 Recalibration time interval Annex A Surface thermometer calibration record reference format Annex B Calibration certificate inside page reference format Annex C Example of uncertainty evaluation of surface thermometer indication error measurement results Annex D Temperature stability of surface temperature source and measurement method of temperature uniformity
