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 connect two compressors in parallel, follow these steps: Make sure both compressors have the same voltage and phase. Install a check valve on each compressor’s discharge line to prevent backflow. Install a tee fitting on each compressor’s discharge line. Connect the two tee fittings with a pipe..
To connect two compressors in parallel, follow these steps: Make sure both compressors have the same voltage and phase. Install a check valve on each compressor’s discharge line to prevent backflow. Install a tee fitting on each compressor’s discharge line. Connect the two tee fittings with a pipe..
The Short Answer: The basic process involves setting up a single pressure switch system linking both compressors, using a check valve to prevent air backflow, and using suitable hoses or pipes.
[pdf] Check out our selection of air compressor parts below! Or use our Air Compressor Parts Lookup with exploded parts diagrams. Always read the owner's manual and check the suggested maintenance schedule first. Drain moisture from tanks when storing.
[pdf] 
