Atlas Copco ZT 55 Instruction Book page 22

Modified cooling water system
The compressor cooling system has been modified to achieve both high cooling water temperatures and
sufficient cooling for the compressor.
The cooling water enters the oil cooler and then flows through the high-pressure compressor element, the
low-pressure compressor element and finally the intercooler and the aftercooler. This sequence ensures
optimal temperature differences with relation to the heat transfer in the individual components.
Pump unit
Atlas Copco supplies pump units to transfer the energy recovered from the compressor to the heat consumer
(HC). The pump unit constitutes a closed water circuit with the compressor cooling system.
Two water pumps (WP1/2) are fitted. One pump circulates the hot cooling water from the compressor through
the heat consumer and back to the compressor. The other is a stand-by pump. Check valves (CV1/2) at the
delivery side of the pumps prevent backflow of water in the stand-by pump. The pump unit is fitted with a
make-up water connection, an air trap with automatic de-aeration device (AT), a pressure and temperature
gauge (PI and TI), a safety valve (SV) and an expansion tank (ET).
Cooling water requirements
Closed recirculating water systems minimise make-up water requirements. Therefore, it is economically
feasible to use softened water to eliminate the problem of scaling deposits.
Corrosion control is important. The best results are obtained by adding corrosion inhibitors as used in engine
cooling systems.
Using anti-freeze products is an alternative solution to avoid problems, e.g. adding 20 % to 30 % ethylene-
glycol based anti-freeze to the tap water.
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Instruction book
APFS998935v00