Atlas Copco GA 11+ Instruction Book page 74

different compressors may not be interconnected before the (atmospheric) collector as this can
damage the electronic drains.
Ventilation
The compressor room should have proper ventilation in order to keep the air inlet temperature of
the compressor under control. The maximum air temperature at the compressor intake is 46°C
(115°F), the minimum temperature is 0°C (32°F). If the room temperature exceeds any of these
limits, the compressor will automatically shut down.
If the unit is equipped with the option "High Ambient Version", it is allowed to operate
the unit up to 55°C (131°F). This option comes with RXD oil filling. A compressor
with the freeze protection option will shut down below -10°C (14°F).
The inlet grids, ducting and external ventilation fan should always be installed in such way that
recirculation of cooling air to the integrated dryer and/or motor compartment is avoided. To
prevent feedback of exhaust air into the cooling inlet, sufficient space should be foreseen above
the unit to evacuate the exhaust air. Otherwise a duct for the exhaust air should be installed.
If ducting needs to be foreseen, a different cooling capacity may be required depending on the
four alternative ducting configurations:
The direction of cooling flows may never be inverted.
The maximum air velocity through the ventilation grids is 5m/s (16.5 ft/s). The maximum allowed
pressure drop in ventilation ducts before or after the compressor is 30Pa. If it exceeds this value,
a fan is needed at the outlet of the ducts. When a duct is foreseen on the air inlet, the ambient
temperature sensor needs to be repositioned in such way that the inlet temperature is correctly
monitored.
If the pressure drop of the ducting is too big to be overcome by the standard fan, it is
recommended to equip the unit with the "Power Duct Fan" option. This option
increases the total allowable pressure drop through the ducts without the need to
install an additional external fan.
For air-cooled compressors and ventilation alternatives 1 and 3
The ventilation capacity required to limit the compressor room temperature can be calculated as
follows:
• For compressors without dryer:
Q = 1.06 N/ΔT
v
• For compressors with dryer:
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Instruction book
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