3-8
“Oil-Less” Scroll Laboratory Air
4107 9006 25.11
3.0 System Operation
Dryer Tower Switching Failure Alarm
(Optional)
For units with this feature, there is one pressure
switch that senses pressure inside each dryer
tower for a total of two pressure switches for each
dryer. If the pressure in both towers of the same
dryer fall below 50 psig, the “Dryer # Switch” on
the alarm screen will change from Green to Red
and the remote dryer fault contacts (one for each
dryer) will change condition (refer to the wiring
diagram that came with the unit for terminal
numbers). A short time delay (1.5 seconds) is
started when both pressure switches fall below 50
psig to eliminate false alarms during normal tower
switching. To eliminate alarms during periods
when the dryer is turned “off ” for maintenance
or other reasons, the dryer tower switching failure
alarm is bypassed for that dryer.
Low Dryer Outlet Pressure Alarm
(Optional)
For units with this feature, there is an adjustable
pressure switch located upstream of the dryer
check valve that will alarm if the pressure in that
line drops below the 75 psig factory setpoint. In
the event of an alarm, the “Dryer # Pressure” on
the alarm screen will change from Green to Red
and a remote set of contacts will change condition
(refer to the wiring diagram that came with the
unit for terminal numbers).
