Intelligent pressure calibrator in the use of attention

The intelligent pressure calibrator is actually a pressure measurement system connected with a pressure transmitter or a pressure sensor and a digital display or a control instrument, and has a general display type and an intelligent control type. The general display type only has the pressure display function. In addition to the system pressure display function, the intelligent control type can also automatically control the system pressure, and some also have a self-calibration function. At present, the country has no procedures in this area. When testing, refer to the JJG875-2005 “Digital Pressure Gauge” verification protocol. Use the method compared with the standard device to perform calibration or calibration. The basic accuracy is 0.05% FS and 0.02% FS. .

When using the smart pressure calibrator in the field, pay attention to the following points:

(1) During the test, the pressure gauge to be tested should be completely disconnected from the equipment piping, and the dirt in the pressure chamber should be eliminated and then connected to the standard equipment. In the measurement of low-pressure gas source pressure equipment of -0.1 to 1.6 MPa, the general pressure calibrator's built-in pressure module and pressure generating equipment are fully capable of performing inspection work. When measuring air pressure equipment of 1.6 to 10 MPa, the general pressure The calibrator requires the use of an external pressure module for testing with a portable hand pump.

The need to pay attention to the cleaning of the pressure gauge under test. After the pressure gauge is disassembled on the site, if it is not cleaned or the cleaning is not clean, it is connected to the pressure calibrator for verification. The dirt will fluctuate along with the pressure and enter the measurement system of the pressure calibrator, the pollution pressure sensor and the pressure Mechanisms that block or block internal pressure lines, wear or scratch seals, affect the measurement accuracy of the pressure calibrator or render it unusable or even directly damaged. In the case of inconvenient on-site cleaning, it is recommended to use a filter between the device under test and the pressure calibrator.

(2) When measuring the pressure measurement system consisting of a pressure transmitter or a sensor equipped with an intelligent digital display instrument at the scene, the indication correction and linear adjustment can be performed on the computer or the display panel through the corresponding calibration software. However, some unexplained causes sometimes encountered in the practice of measurement tasks caused the system pressure to show a large deviation or abnormal display, nor through the software can be adjusted to normal values. There are two steps to deal with such problems:

1 Turn off the power supply of the pressure measurement system, separate the terminals of the pressure transmitter or sensor from the system, and use a pressure calibrator to supply the power to the transmitter or sensor separately and determine the output signal to determine whether it is working properly.

2 According to the different signals received by the digital instrument, input the corresponding signal to the digital display on the circuit where the transmitter or sensor is disconnected. It should be noted that if the digital display itself outputs DC24V, the received signal is a current signal and the connection mode is two-wire system, the current signal must not be directly input by the signal source. Connect the resistor box and the current meter to the circuit and adjust the resistance value. Then the standard current value of the input digital display meter is displayed on the current meter, and the corresponding standard pressure value is calculated and compared with the digital display meter. If the difference is too large and does not meet the technical requirements, adjustments should be made. Transmitter or sensor and digital display are adjusted, then connected together, the whole test once, properly adjusted.

(3) During the calibration, it should also pay attention to whether the pressure equipment is an oil banned device. The pressure calibrator and its external modules and hand pump need to be banned from oil treatment, and an oil-water separator can be connected to ensure the safety of the equipment. . If it is unavoidable to measure in flammable and explosive places, according to explosion-proof requirements such as explosion-proof signs and terminal explosion-proof parameters, refer to the corresponding pressure calibrators, isolation barriers, and safety barriers for pressure verification of safety instruments.

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