They are used to keep the pressure in a tank between a pre-set lower and upper pressure. When the tank pressure crosses the upper or lower limit, an electrical switch is operated. Normally Closed (NC) switch.
[pdf] To sum up, the standard for oil content at the outlet of the oil injection screw air compressor usually requires no more than 3ppm. In actual use, this standard should be strictly followed and effective measures should be taken to ensure the purity and safety of compressed air. Welcome!
[pdf] This test is performed to ensure that there are no leaks in the piping, compressor, or other pressure containing parts of the package. All openings in the completed compressor package are plugged and the unit is pressurized with nitrogen to 350 psig.
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