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Selection skills and disassembly methods of high-precision differential pressure transmitter
The high-precision differential pressure transmitter is a transmitter that measures the pressure difference between the two ends of the transmitter. It outputs standard signals (such as 4-20mA, 0-5V) for measuring the liquid level, density and density pressure of liquids, gases and steam.
What problems should users pay attention to when choosing a differential pressure transmitter? The following editor will specifically introduce the selection points of a differential pressure transmitter, hoping to help users better apply the product.
Key points of differential pressure transmitter selection:
1. Measuring range, required accuracy and measuring function;
2. The environment faced by the measuring instrument, such as the petrochemical industry environment, has flammable (toxic), explosive and hazardous environments, and high ambient temperature;
3. The physical and chemical properties and state of the measured medium, such as strong acid, strong alkali, viscous, easy to solidify, crystallization and gasification conditions;
4. Changes in operating conditions, such as changes in medium temperature, pressure, and concentration. Sometimes it is necessary to consider the changes in the concentration and density of the gas and liquid phases from the start of the drive to when the parameters reach normal production;
5. The structure, shape and size of the container under test must be considered, the equipment accessories in the container and various import and export nozzles, such as towers, solution tanks, reactors, boiler drums, vertical tanks, spherical tanks, etc.;
6. Other requirements, such as environmental protection and hygiene requirements;
7. The selection of engineering instruments must be considered in a unified manner, minimize the variety and specifications, reduce the number of spare parts, and facilitate management;
8. Specific requirements of process patent suppliers.
9. Actual process conditions:
a. Consider what kind of equipment the tested object belongs to. If the tank volume is small, the measurement range will not be too large, the larger the tank volume, the larger the measurement range may be;
b. According to the physical and chemical properties and cleanliness of the medium, conventional differential pressure transmitters and float level transmitters are preferred, and the materials in contact with the medium are selected;
c. For some suspended solids, foam and other media, a single flange differential pressure transmitter can be used. Some plug-in double flange differential pressure transmitters that are easy to precipitate and crystallize;
d. For the liquid level of high-viscosity medium and the liquid level of high-pressure equipment, because the equipment cannot be opened, it can be measured with a radiation level gauge;
e. In addition to measurement methods and technical issues, there are also instrument investment issues.
The composition method of the differential pressure transmitter is very complicated, and there are many various parts, so there are many problems that need to be paid attention to in the process of installation and disassembly. The following editor will specifically introduce some disassembly methods of the capacitive differential pressure transmitter, and I hope it will be helpful to everyone.
Disassembly method of high-precision differential pressure transmitter:
1. Unscrew the instrument cover on the terminal side and touch the signal terminal (power terminal). They are firmly fixed on the electric box, do not disassemble, otherwise it will break the seal between the two chambers, thereby destroying the chamber. The explosion-proof structure does not reach the explosion-proof level.
2. Unscrew the covers on both sides of the circuit, you can touch the smart electronic components and the display head. A good habit should be developed; first disconnect the power supply, and then remove the cover on the side of the circuit.
3. Unscrew the M4 screw fixed on the circuit board, use this M4 screw to screw into the corresponding M4 screw hole of the power amplifier board, you can dial out the power amplifier circuit.
4. When testing the circuit board, first align the zero adjustment screw with the span adjustment screw so that the slot on the test board is perpendicular to the test board, and then the test board can be easily taken out.
5. Remove the nameplate, remove the opening retaining ring installed on the screw, and then remove the zero adjustment, range and adjustment screws.
The components of the differential pressure transmitter are separated from the electrical box:
1. Remove the power amplifier circuit board and verification board, the method is the same as above.
2. Loosen the locking screw.
3. Unscrew the sensor assembly from the electric box, be careful! Do not damage the leads on the assembly, carefully pull the sensor assembly out of the socket from the hole on the electric box, please pay special attention, do not damage the sensor assembly when unscrewing the sensor assembly The diaphragm of the module.
4. The capacitive transmitter components are integral welded parts and cannot be disassembled.