Quincy Compressor QGS 40, Instruction Book

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Cooling system
Cooling system air-cooled compressors
The cooling system comprises air cooler (Ca) and oil cooler (Co).
On air-cooled compressors, the cooling air flow is generated by a fan (FN).
2.3 Regulating system
Unloading
If the air consumption is less than the air output of the compressor, the net pressure increases. When the net
pressure reaches the unloading pressure, solenoid valve (Y1) is de-energised. The plunger of the valve returns
by spring force.
• The control pressure present in the chambers of loading plunger (LP) and unloading valve (UV) is vented
to atmosphere via solenoid valve (Y1).
• Loading plunger (LP) moves upwards and causes inlet valve (IV) to close the air inlet opening.
• Unloading valve (UV) is opened by the pressure in the oil separator vessel. The pressure from the oil
separator vessel is released into atmosphere through the unloader (UA).
• The pressure in the oil separator vessel stabilises at low value. A reduced amount of air is compressed to
guarantee a minimal pressure, required for lubrication during unloaded operation.
Air output is stopped (0%), the compressor runs unloaded.
Instruction book
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