-14-
4.4 Stopping
Close the vacuum valve (A), and quickly open the leak valve (B), and turn the pump
switch off. After the intake side has returned to atmospheric pressure, close leak
valve (B), and seal the intake side. (Refer to Fig. 4.)
Failure to do so may result in burns. The pump becomes hot (40-80ºC) during
operation. After stopping, do not touch the motor or pump until they have cooled.
4.5 Backflow prevention device
This pump is fitted with an oil backflow prevention device. It is effective for preventing
the oil from back flowing when the pump is stopped. (It is not a gas backflow
prevention device.)
The backflow prevention device uses the oil pressure inside the pump to return the
internal pressure to atmospheric pressure when the pump is stopped and to close
the valve directly below the intake.
The backflow prevention device does not guarantee to do this 100%. In the case that
the internal pressure is not returned to atmospheric pressure when the pump is
stopped, approximately 400 ml of oil will enter the vacuum chamber in a short time.
Also, even if the internal pressure is returned to atmospheric pressure when the
pump is stopped, the pressure in the vacuum chamber will return to atmospheric
pressure in a short time.
In addition to installing the vacuum valve (A) and leak valve (B) between the vacuum
chamber and pump as shown in Fig. 4., ensure that there is more capacity between
the pump and vacuum chamber that the amount of the oil backflow.
4.6 Thermal protector
An automatic-recovery type thermal protector is built-in to this pump. This
automatically breaks the circuit of the motor power supply and prevents the motor
from being damaged if the pump stops rotating during operation or if an over current
flows to the motor due to an overload.
Table 4 Thermal protector characteristics
Operating
temperature
Recovery-possible
temperature
130 ºC±5 ºC 83 ºC±15 ºC
Caution
Warning
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