Bimetallic thermometer calibration project and verification method

Bimetallic thermometer calibration project as shown in the figure below: bimetallic thermometer calibration methods are divided into eight steps: 1. Appearance inspection, with visual observation thermometer is in line with the requirements, the subsequent verification and use of test thermometer does not affect the use and the correct reading more defects are allowed; 2. Insulation resistance, with the rated dc voltage for e. between the measured by megger output terminals of the table below, the output terminal and earthing terminal, the insulation resistance between the should comply with the relevant provisions. 3. A value error. Insertion depth of the bimetallic thermometer should accord with the requirement of product specification and according to the total immersion test. B。 Verification of the bimetallic thermometer for the first time, check point should be evenly distributed in the entire measuring range ( Must include measurement, the lower limit) And shall not be less than four. Bimetallic thermometer have 0 ℃ shall include 0 ℃. C。 Subsequent bimetallic thermometer calibration and use of inspection, check point should be evenly distributed in the entire measuring range ( Must include measurement, the lower limit) And shall not be less than three points. Bimetallic thermometer have 0 ℃ shall include 0 ℃. D。 Bimetallic thermometer calibration should be positive and reverse respectively on two trip point by point in the direction of the upper or lower limit, measure the upper and lower limit is only for single trip test. E. In reading test value of bimetallic thermometer it the line of sight should be perpendicular to the dial, use a magnifying glass to read, the line of sight should be through a magnifying glass center. Reading is to be estimated to 1/10 of the index value. F。 Adjustable Angle of bimetallic thermometer calibration value should have been done on the axial position. G。 0 ℃ check, insert the bimetallic thermometer of detecting element, the freezing point of water mixture containing ice box, after waiting for a stable value for reading. H。 Check the other points. Will be checked by bimetallic thermometer detecting element and standard thermometer inserted in the constant temperature trough, after waiting for a stable value for reading. When reading, tank temperature deviation test shall not exceed the thermometer & plusmn; 2. 0℃（ Will be subject to standard thermometer) , write down the standard thermometer and checked respectively thermometer is, the schedule of value. In the process of reading, when the tank temperature does not exceed 300 ℃, its tank temperature change should not be greater than zero. 1 ℃, tank temperature exceeds 300 ℃, its tank temperature change should not be greater than zero. 5℃。 Electric contact thermometer for verification value, respectively, on its lower limit should be set pointer at outside, the lower limit position. 4. Angle adjustment error, error of Angle adjustment test at room temperature, adjustable Angle of bimetallic thermometer from axial ( Or radial) Position adjustment to the radial ( Or axial) Produced in the process of the location of the thermometer is the measure of the change of the value of Angle adjustment error. 5. Return difference, difference of double metal thermometer calibration and verification value at the same time, Check point except upper limit and lower limit) , at the same point, is, the stroke the difference in values, is the dimensions back to the poor. 6. Repeatability, bimetallic thermometer in positive or reverse travel value for verification, at a fixed point on repeated many times ( At least three times) Value for verification, is calculated for each point the same trip in value between the biggest difference is the repeatability of bimetallic thermometer. 7. Bimetallic thermometer error value for calculation. Elected to use the standard mercury thermometer, standard mercury thermometers do standards: thermostatic bath = standard thermometer + value for the actual temperature thermometer revised by checking the error value of the thermometer = checked thermometer - value Constant temperature trough actual temperature standard copper - elected Copper and nickel thermocouple do standards: checked the error value of the thermometer = checked thermometer - value Thermostatic bath temperature calibration results, for inspection of bimetallic temperature of plan hair verification certificate, inspection unqualified bimetallic temperature verification results of plan hair notices, and indicate the unqualified project.