With the help of a mechanical control valve (the proportional controller), the opening and closing of
the inlet valve is continuously varied in relation to the actual air demand. The airend provides com‐
pressed air for connected consumers.
This continuous delivery regulation minimises the fuel consumption of the engine. The load and
fuel consumption of the engine rises and falls with the air demand.
4.5 Safety devices
4.5.1 Monitoring functions with shut-down
The following functions are monitored automatically.
■ Engine oil pressure
■ Coolant temperature
■ Airend discharge temperature
■ Engine-generator
The fuel stop device is activated when an alarm occurs. The engine comes to a stop and the
venting valve releases pressure from the machine.
4.5.2 Further safety devices
The following safety devices are provided and may not be modified in any way.
■ Pressure relief valve:
This valve protects the system from excessive pressure. It is factory set.
■ Enclosures and covers over moving parts and electrical connections:
These protect against accidental contact.
4.6 Options
The options available for your machine are described below.
4.6.1 Option cb
Manually setting the output pressure
The option “Proportional controller with manual adjustment option” allows you to manually set the
machine’s output pressure.
Discharge pressure is adjusted manually on the proportional controller. The output pressure can
only be set lower than the maximum working pressure of the machine.
If the max. working pressure is exceeded as a result of improper manual setting of the proportional
controller a second safety valve protects the pressure system from impermissible pressure rise.
The second safety valve is located upstream of the compressed air outlet on the oil-free side of the
compressed air system.
Further information See chapter 8.2 for manually setting the machine’s output pressure.
4
Design and Function
4.5
Safety devices
44
Operating Manual Portable Rotary Screw Compressor
MOBILAIR M27 PE
No.: 9_9548 22 HCE