Selection of normative machinery and equipment There are various normative machinery and equipment models and specifications that can be used for testing and verification, and the requirements written in the technical specifications are standard. For the current signal, working voltage, and resistor data signal standardizer, the deviation of the application point should not exceed 113 of the basic deviation limit of the meter under test. Frequency The frequency meter is within the application frequency range, and the deviation should not exceed ± 0.001%.
做 Preparation of checklist and instrument panel verification
① Select the verification points. The temperature and working pressure of the meter to be checked are entered into the safety channel. According to the technical specifications of the temperature digital display instrument and the general large digital digital display instrument, 5 points are selected for verification, and the verification records are filled independently.
② The flow verification point should be selected to include the limit, and more than 5 points within the 10% limit (the flow rate is linearly related to the square root of the input data signal, the verification point should include the limit, and more than 5 points within the 25% limit)
③ The check sheet is made under the working condition standard of the design scheme. The working condition of the design scheme is tf-td, and pf = pd. At this time, formula (7.1) to formula (7.3) can be selected according to the type of flow data signal to measure the required range of each verification point. The same secondary meter suitable for single-pulse output flow controllers and smart transmitters should also calculate the basic theoretical frequency of each verification point.
④ The check sheet is made under the offset design scheme working standard. When the substance to be measured is steam, two relative densities of the working conditions are selected around the design of the working conditions of the steam kiln degree, one is the ultra-low pressure working condition close to the saturated water vapor, and the other is the high-density working condition with a high bottom pressure. Substitute equations (7.39) to (7.44) (set k. = 1, ne. = 1) to measure the standard deviation of the flow rate and the matching frequency (the same as the secondary table equipped with the flow controller with single pulse output), and verify At each time, according to the working pressure and temperature values of these two working conditions and their flow data signal values, send data signals to the meter under test, and load the flow range.
For general steam, take the working pressure and temperature that the application target will exceed, and substitute the working pressure and temperature into equations (7. 10) to (7.12) respectively to obtain the compensation index for two types of working conditions (take Zf-Zd ), And then substitute equations (7.3 9) to (7.41) (set k. = 1, k. = 1) to measure the standard deviation of the flow rate at each verification point and its matching frequency (same as the single pulse output flow controller, The secondary meter applicable to the smart transmitter) sends the data signal to the meter to be checked according to the temperature working pressure value and the flow data signal value of these two working conditions during the calibration, and loads the flow range.