Protective Devices
The following protective devices are available to protect the unit from being damaged and to help with
maintenance.
♦
High Temperature Switch (standard except on
Vmax
LT
):
will signal when the temperature of the oil
is exceeding the shut-down level. The switch will shut the unit down. The unit will not restart until the
alarm condition is acknowledged and is reset. The switch is a “snap disc” type of switch that is
normally closed. When the temperature reaches the maximum setpoint, the switch will open. Once
the switch has opened, there is a 10-20
o
F differential that the temperature will need to drop to, in order
for the switch to close.
♦
High Back-pressure Switch (optional):
is installed on the discharge of the separator. When the
back-pressure reaches a pre-determined level (4 psi), the switch will signal the control panel. A high
back-pressure light may be installed on the control panel, which, when illuminated, signals that the
exhaust element in the vacuum pump needs to be replaced. Note that the high back-pressure switch
will not shut the unit down, but the exhaust element must be replaced as soon as possible.
♦
Lag Pump On Alarm (optional):
An NFPA 99 requirement on medical systems. This is an
audio/visual alarm that signals lag pump operation. Once the alarm triggers, the alarm must be
acknowledged and reset. The alarm will not reset if the lag pump is still in operation. This alarm
indicates vacuum is greater than the supply of the lead pump only.
♦
Transformer Failure Light (optional):
All standard medical NFPA 99 oil-sealed liquidring vacuum
pump systems are supplied with two (2) control voltage transformers (one primary and one for
backup). If indication is desired in the event that the primary transformer fails and the backup
transformer picks up, a TRANSFORMER FAILURE light will be necessary. The defective transformer
should be replaced as soon as possible. When the primary transformer fails, the operation of the
system will not be interrupted. If the backup transformer also fails, the system will shut down.
♦
Low Oil Level Switch (optional):
This switch is installed in the separator/reservoir of the liquidring
vacuum pump. It is a float type of switch. If the level switch is triggered, the affected pump will shut
down. The LOW OIL LEVEL light on the control panel will be illuminated. The low level switch will be
wired into the main alarm of the panel. The alarm will have to be reset to restart the pump.
When
filling the system with oil, make sure that the power to the pump is off because if the alarm
reset button has been reset and the level switches contacts close while filling the pump, the
pump will start-up automatically.
♦
Frequent Stop/Start Protection (standard on multiplex systems):
Allows each pump to run a
minimum amount of time. Frequent stopping/starting can reduce coupling life and is also less efficient
from a power consumption standpoint.
♦
Automatic Alternation (standard on multiplex systems unless otherwise specified):
Allows the
pumps to alternate. The primary feature of automatic alternation is to equalize the running time on all
the pumps.
Dekker Vacuum Technologies, Inc. – Vmax/13
19
