Maximum frost protection is ensured with an antifreeze concentration of 55% volume, as frost pro‐
tection and heat transfer properties deteriorate beyond this point. Higher concentration also leads
to higher operating temperatures for the engine.
1.
The engine can be damaged if the antifreeze concentration is insufficient.
Corrosion.
Damage to the cooling system.
Engine housing fracture.
➤ Check coolant.
➤ Protect the coolant against freezing.
➤ Replenish immediately if necessary.
2. To test the coolant, use the coolant tester as instructed by the manufacturer.
Concentration of antifreeze is too low: Change the coolant.
Performing final work steps:
1. Replace the filler cap.
2. Close the door.
10.4.1.3 Mixing the coolant
The coolant is a mixture of clean, fresh water and an antifreeze containing added anti-corrosion
agent.
For corrosion protection reasons and the need to raise the boiling point, the coolant must remain in
the cooling system throughout the year.
The maximum permissible coolant life is 3 years.
Never use water without coolant added. Water alone is corrosive at engine operating temperatures.
Water alone does not offer sufficient protection from boiling or freezing of the coolant.
An adhesive label with the recommended mixture ratio for the coolant is fitted by the coolant ex‐
Fig. 27 Recommended mixture ratio for coolant
1
Anti-corrosion agent/antifreeze
2
Water
➤ Observe the coolant recommendations given in Chapter 2.8.4!
Preparing the coolant:
Precondition The coolant used must meet the specification of ASTM D4985.
10 Maintenance
10.4 Drive engine maintenance
102
Operator Manual Portable Rotary Screw Compressor
MOBILAIR M55 PE SIGMA CONTROL SMART pV
No.: 902366 10 USE
