First,Diaphragm pressure gauge failure reasons and maintenance methods
Diaphragm pressure gauges are widely used to indicate and measure local pressure in contact with strong corrosive media in production. They are easily damaged during use, so many pressure gauges are scrapped. The main reason for the damage is the corrosion, damage and leakage of silicone oil caused by the long-term placement of the instrument on the chemical site. In order to reduce costs and turn waste into treasure, the maintenance problem of diaphragm pressure gauges must be solved. Here the company summarizes a set of maintenance methods for everyone.
1. The difference between the pressure measurement principle and structure of the diaphragm pressure gauge and the ordinary pressure gauge
The pressure measuring principle of the ordinary pressure gauge is: introduce the measured pressure into the pressure measuring spring. After the spring tube is compressed, it produces elastic displacement, which drives the connecting rod and the central gear to deflect, and the pointer is installed on the central gear shaft to display the pressure. Measurements. The so-called diaphragm pressure gauge, in addition to the part with the ordinary pressure gauge, adds a connecting flange and an isolating diaphragm (the isolating diaphragm can be made of different materials to adapt to different corrosive media or temperatures). The pressure transmission medium silicone oil is filled between the isolating diaphragm and the pressure spring tube.
The main difference between the diaphragm pressure gauge and the ordinary pressure gauge is that in the pressure measurement process of the diaphragm pressure gauge, the measured medium only contacts the isolation diaphragm. This prevents corrosive and crystalline media from entering the spring tube and avoids corrosion and clogging of the spring tube.
Second. Cause Analysis of Diaphragm Pressure Gauge Failure in Us
1. When the diaphragm pressure gauge has pressure, the pointer has no indication. The reason for this failure is generally that the connection between the pointer and the central gear shaft is loose due to strong vibration, and the compressed displacement of the spring tube cannot drive the pointer to deflect. Secondly, the silicone oil in the spring tube leaked too much and could not transmit the pressure.
2. If the diaphragm pressure gauge has these faults: the measured pressure is inaccurate, the pressure indication changes at the low end, and the pointer does not change when the pressure rises, then the reason is that a small part of the silicone oil is lost in the spring tube, allowing air to enter. Because gas can be compressed, the needle indicates inaccurate or motionless pressure as the pressure increases.
3. During the pressure measurement, the pointer changes by leaps and bounds. This failure of the diaphragm pressure gauge often occurs when the diaphragm pressure gauge is under large vibration (such as the outlet pressure of the pump). Due to the fluctuation of pressure, the pointer also swings back and forth, causing serious wear of the central gear of the pressure gauge core, and the poor coordination between the central gear and the sector gear, resulting in a sudden change of the pointer.
For the treatment of pointer jumping failure, small miscellaneous files and scrap saw blades can be used to file and repair the worn central gear. When the shaft hole of the pointer becomes larger, tap it with a small hammer to shrink it until the pointer is tightly combined with the central gear shaft. In addition to proper maintenance, it is also important to choose a reliable pressure gauge supplier when purchasing the product.
Third, the maintenance of the diaphragm pressure gauge
During repairs to multiple diaphragm pressure gauges, it was found that most of the failures were caused by leaking silicone oil in the spring tube. It can be said that filling the spring tube with silicone oil is the key to solving the maintenance of the diaphragm pressure gauge, but filling the spring tube with silicone oil is not an easy task. Under normal circumstances, manufacturers have special silicone oil filling equipment, and use a vacuum pump to extract the air in the bomb tube. In the case of negative pressure, let the silicone oil automatically flow into the spring tube.
