1 Main factors affecting the sealing performance of hydraulic valves
The main factor of seal element damage is impurities in the working fluid. These impurities grind between the sealing elements, causing the valve to leak. Therefore, it has been proposed abroad that the corresponding grade of hydraulic components should be used with the corresponding precision filter. They believe that a 5µM oil pump seal element with a filter accuracy of 3/µM will last 10 times longer than a 10µM filter.
But the hydraulic support valve, the working environment is very bad. In the coal mining face, the total length of the oil pipe is more than 1000 meters, the joint socket is more than 4000, and the liquid tank has no special dustproof facilities. There are a lot of floating impurities in the emulsion, leaving more pulverized coal, rock particles and iron filings in the bottom of the column cylinder and the valve chamber. Inlet spool and seat, due to more frequent opening and closing, liquid flow rate is high, the seal will soon fail. Practice has proved that it is very difficult to reduce the pollution impurities in the fluid of the support hydraulic system, and some people have envisaged the use of high pressure filters in the emulsion pump station, while adding small filters at the entrance of each support. However, it is quickly blocked in the work, forming a cut-off.
On the other hand, with the development of hydraulic support technology. Higher requirements are put forward for the performance and service life of the valve. At present, the valve life is measured by the total flow rate of the emulsion passing through the valve under test and the number of valve openings and closures in the condition of 120 mesh filters and magnetic filters. But there is a great difference between the indoor type test and the actual underground work. Now many countries of the form of the experiment, increase the anti-pollution requirements, some in the emulsion into the appropriate pulverized coal, some add mechanical impurities.
For this reason, it is necessary to use a new type of sealing pair with strong anti-pollution ability and suitable for underground working conditions.