The ideal situation is with the oil level around the optimum mark when the machine is running.
In frequency-controlled compressors (SFC) the oil level indicator is only accurate when the ma‐
chine is running at or near maximum speed. The lower the pressure at the compressed air outlet,
the higher the speed.
Operating state
Minimum oil level
Maximum oil level
LOAD
Tab. 44 Permissible cooling oil level under LOAD
Precondition The machine has been running at least 5 minutes under LOAD.
Fig. 22 Checking the cooling oil level
1
Minimum oil level
2
Maximum oil level
3
Optimum oil level
➤ Check the cooling oil level with machine running under LOAD.
Result As soon as the minimum level is reached: Replenish the cooling oil.
10.9 Venting the machine (depressurizing)
Venting takes place in three stages:
■ Isolate the compressor from the air system.
■ Vent the oil separator tank.
■ Vent the air receiver.
The machine must be isolated from the compressed air network and completely vented be‐
fore undertaking any work on the pressure system.
Material The maintenance hose with hose coupling and shut-off valve needed for venting is lying on the ma‐
chine.
Precondition The power supply disconnecting device is switched off,
The device is locked off,
A check has been made that no voltage is present.
10 Maintenance
10.9 Venting the machine (depressurizing)
64
Operator Manual Screw Compressor
AIRTOWER 3C–7.5C Tri-Voltage
9_6917 34 USE
