CAP-835
32
6 Operation
6.1 Safety instructions for
operation
Improper operation
WARNING!
Danger of injury due to improper
operation!
Improper operation can cause
serious injury and significant
material damage.
- Carry out all operating steps in
accordance with the information
and notices in this manual.
- Pay attention to the following
points before starting work:
- Ensure that all covers and
safety devices are installed
and work properly.
- Ensure that that no one is in
the danger zone.
- Never override or bridge safety
features during operation.
6.2 Modulation Control
General description
The modulation valve allows the compressor to
unload and then load gradually to meet system
air demand. As demand decreases and system
pressure increases above the modulation valve
low setting, pressure is passed to the inlet valve
piston, which closes enough to match the air
system demand, preventing the compressor
from switching to unload. When the system air
demand falls below 50% of full flow the
controller switches the compressor to unload.
Changing the setting of the modulation valve
The modulation valve is not set at the factory.
The compressor will run load/unload. To set
modulation control refer to the following
paragraph.
Fig.32: Changing the modulating valve setting
To change to modulating control, start by
loosening the jam nut (Fig. 32-2) and turning the
set screw (Fig. 32-1) counter-clockwise. This
lowers the pressure setting of the modulating
valve. This adjustment should be made slowly.
The desired pressure settings in the controller
should be set prior to adjusting the modulation
valve. The modulation valve should be set to
“weep” air from the vent hole (Fig. 32-3) in the
valve dome at 7-8 PSI (0.5 bar) less than cutout
pressure setting. Once the desired modulation
control pressure is set, tighten the jam nut.
If the screw is completely turned in (clockwise),
modulation is no longer operational (=factory
setting). The unit will run in regular load/unload
again.
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