In China, multi-way valves are still in the process of research and development. So, compared with those valves which have been developed for a long period, multi-way valves will meet more troubles in normal use. The following is the analysis of these failures:
1. Noise caused by uneven pressure
When in high-pressure situation, the orifice area of pilot valve is very small, as well as the axial mouth (only 0.003cm to 0.006cm), but the flow speed can be very fast, reaching 200 meters per second. All these will lead to the uneven distribution of pressure and vibration (due to unbalanced radial force) easily. It is generally believed that the pilot valve is the noise resource.
2. Noise caused by cavity
Because of various reasons, air will be drawn into the oil. Or part of the air, which is dissolved in the oil, will be precipitated out and shape into bubbles. In low-pressure area, these bubbles are in large volume, but once they flowing to the high-pressure area along with oil, due to the compression, their volume will suddenly be smaller or the bubbles will disappear.
3. Noise caused by hydraulic shock
When unloading pilot-operated pressure relief valves, pressure from hydraulic circuit will drop quickly and make impulsive noise. The higher the pressure is, the larger the volume working condition is, and the louder the impulsive noise will be. Because of the time for unloading is short, the flow speed of oil will be changed drastically and thus will make the pressure drop suddenly and impact the pressure wave.
4. Mechanical noise
Mechanical noise from pilot-operated pressure relief valves is normally caused by the strike between components and friction because of machining error. Generally, the way to reduce or eliminate the noise is to install an absorber in pilot valve.
Through the analysis above, there are many reasons for the failure of multi-ways valves
and these failures will have a certain influence on the application of multi-way valves. So, we need to solve these problems, not only for working environment, but more for working efficiency.