4B.1 Vacuum Control System
4B.1.1 System Description
The VerusLab Lubricated Rotary Vane Laboratory
Vacuum System is U.L. labeled. The basic control
panel includes a visual and audible lag pump
alarm, a visual and audible system alarm,
emergency stop, and a 0-30” Hg vacuum gauge.
It also has the following for each pump: 24V
power supply with fuses, hour meter, vacuum
control switch, high discharge air temperature
switch with alarm, illuminated Hand-Purge/O
ff
-Auto (H-P/O-A) switch, motor starter and circuit
breaker with external disconnect. All components
are enclosed in a NEMA 12 enclosure.
WARNING:
Never run the pump without lubricating oil!
4B.1.2 System Operation
The central vacuum system operates by
manipulating the pump(s) to supply the vacuum
requirements. The receiver tank is used as
a ballast to cushion the e
ff
ect of vacuum
consumption versus vacuum production.
During normal operation, all H-P/O-A switches
should be turned to the “AUTO” position so that
the Programmable Logic Controller (PLC) can
e
ff
ectively control the system (See Figure 4B.2).
The PLC monitors the system vacuum switch
condition, starts and stops the pumps depending
on changing vacuum switch conditions and run
time values, and automatically alternates the lead
position between units. Automatic alternation
of all vacuum pumps is based on
fi
rst-on/last-
o
ff
principle with provisions for simultaneous
operation if required. The lead vacuum pump will
alternate based on the set alternation time. The
alternation timing is
fi
eld adjustable between 4
to 24 hours with factory setting at 10 hours. See
Figure 4B.3 for the potentiometer settings.
When vacuum is needed, it comes
fi
rst from
the receiver tank. Once the vacuum level in the
receiver drops to the minimum switch setting,
the PLC will signal the lead pump to start. If the
lead pump cannot raise or maintain the vacuum
level in the receiver, the next pump (lag pump in
NOTE:
This section is only applicable to Lubricated
Rotary Vane Laboratory Vacuum Systems
with the Basic control system.
Figure 4B.1 Control Panel Layout
Lag Pump/
System
Alarm
Disconnect
Switch
Vacuum
Gauge
Hour
Meter
Control
Switch
High
Temperature
Alarm
Emergency Stop
Figure 4B.2 Hand-Purge/O
ff
-Auto Switch
Lubricated Rotary Vane Laboratory Vacuum Systems
4107 9021 88.01
4B-1
4B.0
General Operation - PLC
