Product Manual

2022 2096 26 19
Instruction book
2.4 Regulating system
Automatic Start/Stop
The regulating system includes:
• Check valve
• Air pressure switch (MDR) with pressure release valve and on/off button (S1).
Operation
The air pressure switch opens and closes its contacts at pre-set pressures. During loaded operation, the
contacts are closed: the motor is running.
When the pressure in the air receiver reaches the pre-set maximum pressure, the contacts as well as pressure
release valve are opened. The motor stops, the air at the delivery side of the compressor is vented to
atmosphere and the check valve closes to prevent venting of the receiver.
When the pressure in the air receiver decreases to the pre-set minimum pressure, the contacts of the air
pressure switch close and the pressure release valve closes. The motor restarts and compressed air is supplied
to the receiver again.
CR Contractor
The regulating system includes:
• Pilot valve
• Unloader with integrated check valve
Operation
The pilot valve opens and closes at pre-set pressures. During loaded operation, the pilot valve is closed,
preventing the compressed air from flowing to the unloader.
When the pressure in the pulsation dampers reaches the pre-set maximum pressure, the pilot valve will open.
Compressed air from the pulsation dampers will flow to the plunger which causes the unloading valve to
open. The air at the delivery side of the compressor is blown through the silencer to the atmosphere and the
check valve closes to prevent venting of the pulsation dampers. The compressor runs unloaded.
When the pressure in the pulsation dampers decreases to the pre-set minimum pressure, the pilot valve closes.
Control air from the unloader plunger chamber is vented to the atmosphere. The unloading valve closes and
compressed air is supplied to the pulsation dampers again.