Bimetallic thermometer calibration requirements

Bimetallic thermometer calibration requirements ( 1) The appearance of inspection. Appearance should satisfy: accessories firm, smooth, clean, no corrosion, loose; G line complete, cleaning, glass clean, does not affect the readings; Pointer is complete, a pointer not to be exposed to dial, but also cannot too far away, generally no more than 5 mm; On the dial of the thermometer should have the detailed information of the thermometer, and clearly visible. （ 2) Error value for examination. The immersion length of the thermometer should be full immersion inspection or directly in accordance with the requirements on the manual submerged, first check the thermometer, check point (must be at least four, subsequent verification can have three, and the monitoring should be evenly distributed throughout the entire measuring range. When measuring upper limit and lower limit, only one-way trip verification is required, while other position need to check each point. （ 3) Angle adjustment error checking. The inspection can be done at room temperature, Angle adjustment error values shall abide by the requirements cannot be greater than the maximum permissible error absolute value. （ 4) Check back to the poor. This examination should be performed with the check of error at the same time, also should abide by the requirements cannot be greater than the maximum permissible error. （ 5) Repetitive tests. In thermometer and return difference value for inspection, respectively the number of repeat on each inspection point, should be repeated at least three times, and the repeatability of bimetallic thermometer should be not greater than the maximum permissible error of the absolute value of 1/2, the in the thermometer to use or not will check items in a subsequent verification. （ 6) Set point error checking. Verification of the thermometer should be in the range 0 for the first time. 1, 0. 5 and 0. 9 three set point, the follow-up checks and to use in the testing set point error allowed in only one temperature point ( By the user's request to order) , the error of the set point should not greater than the maximum permissible error of 1 as required. 5 times. （ 7) Switch bad check. On the same set point, the difference between the switch value and lower switching value both for the switch. For bimetallic thermometer calibration for the first time, the examination can and set point error checking simultaneously, and the set point to the requirement of the same error requirement. （ 8) Switch repetitive checks. Switch the repeatability is the first time for check the thermometer, on the same set up checkpoints, calculate the biggest difference between this point and switching value, and then calculate the biggest difference between this point and switching value value, and then take the maximum, the inspection error requirement should be not more than half of the maximum permissible error. （ 9) Thermal stability check. Thermal stability check should be twice, insert the thermometer the thermostatic bath, in online when temperature is 300 ℃ for 24 h, 400 ℃ for 12 h, 500 ℃ for 4 h, in the process, limit the range of temperature is not greater than 2 ℃, and then after cooling in the thermometer, again for a second test, so that to calculate the error value for each point, also not allowed to exceed the prescribed value error of the maximum permissible error. 2. 6 verification period is generally within a year, but by the usage of the thermometer and environmental situation to decide. Bimetallic thermometer is a kind of measurement in the field of low temperature meter, can be directly measured in the production of all kinds of temperature of 80 ℃ to 500 ℃ below zero in the scope of the temperature of the liquid vapor or gas medium, for the accuracy of the bimetallic thermometer must pass through the regular check to determine, through the determination of the bimetallic thermometer regulation project, to determine the accuracy of measurement of bimetallic thermometer, so as to select the calibration or replacement, can effectively avoid the problems caused by inaccurate measurement data.