How to solve the leak and blockage of the pressure transmitter pressure tube?

   The pressure transmitter circuit uses a two-wire current transmission method. The two-wire transmission allows the transmission of the electric and signal signals to be completed by the same pair of wires. Since the signal is transmitted as a current, the long-distance transmission can be better overcome to reduce the voltage and the effects of noise from the motor, delay switch, and industrial equipment on the system. The pressure signal is changed to a differential voltage by the sensor. Then, the voltage signal proportional to the pressure is converted into a current signal of 4-2OmA through the XTR101 two-wire transmitter. The side of the current signal can be observed with an ammeter in series with the loop, and the voltage at both ends of the side disk can be used to indirectly measure the loop power. The pressure transmitter uses the current to transmit the signal. Therefore, the electrical supply, the load, and the ammeter in the circuit are connected to the circuit in the form of a joint. The typical load of the system is a resistance of several hundred ohms.

       Read the product sample and instruction manual before installing the pressure transmitter. The pressure interface should not leak during installation to ensure the correct range and wiring. The outer casing of the pressure sensor and transmitter should be grounded. The signal cable should not be mixed with the power cable. Strong electromagnetic interference should be avoided around the sensor and transmitter. Sensors and transmitters should be periodically verified in accordance with industry regulations during use.

       Capacitive Pressure Transmitter Common Fault Analysis and Processing Method Capacitive pressure transmitter measures part of the sensitive components using all-welded structure. Some electronic circuits are installed with wave soldering and connectors. The overall structure is sturdy and durable with few faults. For most users, if a fault occurs in a sensitive part, it is generally not possible to repair it by itself, and the manufacturer replaces its entire component.

       The failure of the transmitter section to verify the transmitter's measurement section may result in no output or output anomalies from the transmitter. Therefore, the sensitive part of the sensor should be checked first. Remove the flange and check the sensitive part of the diaphragm for deformation, damage and oil leakage. Remove the compensation plate, do not remove the sensitive parts, check the insulation resistance of the pins on the case. In the case of insulation resistance, the voltage should not exceed 100V and should not be less than 100MΩ. When the pressure signal is the upper limit of the range, the gas supply is turned off and the output voltage and reading value should be stable. If the output voltage drops, the transmitter leaks and you can use soap and water to check for leaks.

       The transmitter circuit part checks the connection power supply. After the input pressure signal is given, check the transmitter output voltage signal status. If there is no output voltage, first check if the power supply voltage is normal; if the power supply requirements are met; the wiring between the power supply and the transmitter and the load device is wrong. If the transmitter terminal has no voltage or polarity reversal, the transmitter may not output a voltage signal. After eliminating the above reasons, further check the amplifier circuit board assembly for damage; the board connector may or may not be in contact with the normal instrument measurement voltage and the corresponding measurement voltage comparison method to determine the fault point, if necessary, Replace the defective amplifier board. In the case of flow type transmitter inspection, the J-type amplifier board should pay special attention to take anti-static measures.

       If a given input pressure signal is applied, the transmitter output is too high (greater than 10 VDC) or the output is too low (less than 2.0 VDC) and the input pressure signal changes and zero is adjusted. For this type of fault, check that the “Oscillation Control Circuit Section” of the transmitter power amplifier board is working properly, except for the transmitter measuring certain sensitive components. The normal peak voltage between the high-frequency transformer T1-12 should be 25~35VP-P; the frequency is about 32kHz. The amplifier board then checks the operation of the op amp; if the part is damaged, etc. This type of failure requires the replacement of the amplifier board. Transmitter online design and process assembly quality requirements are very strict, in the actual use of the line fault, after verification and confirmation, and the manufacturer's replacement of the faulty circuit board to ensure the long-term stability and reliability of the instrument.

      The site failed to check for faults at the construction site, mostly due to the use of pressure sensors and incorrect installation methods, summarizing several ways.
1. After the components (holes, remote measuring connectors, etc.) are blocked or installed incorrectly, take unreasonable pressure points.
2. The pressure tube leaks or clogs, there is residual gas in the liquid filling tube, or there is residual liquid in the inflation tube. There is a deposit in the process flange of the transmitter that forms a dead zone.
3. The transmitter wiring is incorrect, the power supply voltage is too high or too low, and the contact between the meter head and the meter terminal is poor.
4. It is not installed in strict accordance with the technical requirements, and the installation method and on-site environment do not meet the technical requirements.

Read more:
Intelligent pressure transmitter performance and characteristics