Ulvac GLD-137CC, Instruction Manual

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4.6 Thermal protector
Auto reset thermal protector is incorporated in the motor in order to interrupt the power circuit
of the motor and prevent damage to the motor when an over current flows through the motor
due to a stop in rotation or overload resulting from the pump malfunctioning during operation.
Table 2 Characteristics of the thermal protector
Operation temperature 120
±
5
℃
Reset temperature 78
±
9
℃
When the thermal protector has been actuated, turn off the switch and contact us.
The motor is very hot when the thermal protector has actuated. Never touch it with your hand.
When the cause of the malfunction has been eliminated, check that the motor has cooled down,
and restart operation (see “
6.5 Trouble check list
”).
The pump’s surface becomes hot (temperature increase under non-load
operation: 25K, temperature increase under high-load operation: 75K). There
is a risk of burns. Do not touch the motor or the main unit of the pump after
the pump has stopped until it cools down completely.
4.7 Gas ballast valve
The pump is equipped with a gas ballast valve in order to evacuate vapor and condensable gases
such as solvent vapor.
Evacuated condensable gas that liquefies in the compression and pressurization processes of the
pump is mixed with the pump oil and starts circulating through the pump together with the oil.
In such a case, the same effect as when oil of a high steam pressure is used is produced, and the
ultimate pressure of the pump increases. Moreover, the lubricity of oil deteriorates and the
service life of the shaft seal is shortened.
If air or dry nitrogen enters through the gas ballast valve just before the compression and
pressurization processes of the pump, condensable gas will not liquefy and will be exhausted
together with air through the outlet valve. When the gas ballast valve is used, the “gas ballast
effect” increases as the pump temperature becomes high. So, before evacuating condensable gas,
perform operation for approximately 20 minutes with the gas ballast open, and after the pump
temperature reaches approximately 5
0
～
65
℃
, open vacuum valve (A) and continue operation.
If the temperature is low, a satisfactory “gas ballast effect” is not achieved.
If the gas ballast valve is left open when condensable gas is not evacuated, not only does the
pump oil scatter and power is lost, but also the ultimate pressure increases. Furthermore, since
the gas ballast valve’s capacity to process condensable gas is limited, condensable gas remains
in the pump oil when a lot of condensable gas is exhausted or when condensable gas (air and
gas containing small amounts of moisture and other vapor which make the oil dirty) is
exhausted without opening the gas ballast valve. In such a case, perform non-load operation
with vacuum valve (A) closed and the gas ballast valve open. Then the oil temperature increases
and the pump oil is purified due to the effect of the gas ballast valve. Continue non-load
operation with the gas ballast valve closed until the specified pressure is reached. If the pump
oil is not cleaned even a long time, replace the pump oil.
Caution