During the daily use of pressure sensors, users often ignore some preventive maintenance work. The pressure sensor and the differential pressure sensor can be remotely operated online through the hand-operated communicator, which greatly facilitates the maintenance of the instrument, so that we don't need to go to the scene to observe the sensor frequently in daily maintenance. In addition, the reliability of this type of instrument is high, so the problem is the neglect of it. It is difficult to find the existence of hidden dangers before the failure occurs. We need to pay attention to the following questions.
-
Corrosion protection for the pressure sensor maintenance
The environmental conditions of chemical production are poor, and most of the measured medium are corrosive, so the biggest threat to the sensors installed in the field is corrosion. Corrosion problems such as the high pressure chamber, low pressure chamber, diaphragm, case, pressure guiding tube and valve of the sensor. Therefore, it is also important to select a reasonable material according to the measured medium and reasonably select the installation position of the sensor. It’s preferably to install the sensor in the field with an instrument protection box. When it is necessary to open the sensor housing for calibration or overhaul, be sure to tighten the housing after the work is completed, otherwise it may occur the output value drift. Because the electronic circuit board is installed in the housing, if the housing is not tightened, the circuit board may be eroded by moisture, rain, and corrosive gases, then damage the normal working conditions of the electronic circuit board. Moisture causes the board to get wet, resulting in a drop in insulation performance, causing drift in output values. The lock nut connecting the housing to the high and low pressure measuring chambers is painted with the sealant. If it is need to remove it, the nut should be tightened and repaint the sealant.
For
pressure sensors and differential pressure sensors inside the anti-corrosion problem, select the correct structural materials and seals of the sensor according to the measured medium. When measuring liquid and water, the measuring chamber of the sensor and the pressure guiding tube should adopt heat preservation and heat tracing measures. When the temperature of the measured medium is too high, use the isolation fluid to protect the measuring chamber and the diaphragm. Isolation measures should also be taken when measuring corrosive media.
-
Leak prevention for the pressure sensor maintenance
If there is a leak point in the joints, valves and three-valve of the pressure guiding tube used with the pressure sensor, the measured data will be abnormal. That is, the pressure received in the high and low pressure measuring chambers of the sensor cannot correctly reflect the true pressure of the process, causing measurement errors. For liquid or steam it is easier to find leak points. However, for gas, we can only use comprehensive inspection and judgment to determine whether there is leakage. We can use soapy water to check for leaks when necessary. Leak checking focus on the joints of the pressure guiding pipe, the ferrule interface, the valve joint, the exhaust valve and drain valve in the high and low pressure chamber, etc.
-
Anti-clogging for the pressure sensor maintenance
Blockage often occurs in the pressure guiding tube and valve. The most difficult to find is the impurities in the pressure guiding tube and the valve. The fluid make them be in a micro-conducting state. Due to poor transmission, the pressure or differential pressure measurement transmitted to the pressure sensor may be delay, and the pressure or flow of the process may not be reflected in time. There is also a phenomenon that the clogging only occurs in one pressure guiding tube, which may cause the output signal of the differential pressure sensor to be large or small, resulting in a significant decrease in the fluctuation of the measurement signal, which can be judged empirically. However, the most important thing is to sewage and flush the pressure guiding pipe strictly according to the time specified in the regulations. When it is found that there is blockage, it should be treated in time to ensure the smooth flow of the pressure guiding pipe.
-
Anti-misoperation for the pressure sensor maintenance
Since the pressure sensor and the
differential pressure sensor have high reliability, set their operation a time they can operate normally for a long time, so the chance to set and contact the sensor in daily work is relatively small. However, due to the large number of set functions in the sensor, the problem that comes with it is that the operation is complicated, so that an operation error or a setting error may occur, which is disadvantageous for the correct use of the sensor. Therefore, in actual use, you should read more product manuals or user manuals, and thoroughly understand the meaning and setting method of each parameter to avoid the operation and setting errors.
