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4.2 Operation of the Thermal Protection Relay
1)
When the thermal protection relay operates, immediately set the power switch to 'O',
remove the power cord from the outlet, and contact the manufacturer. Note that the motor
will be very hot and should not be touched.
2) Once the cause of the fault has been removed, wait until the motor cools and restart
operation.
When the thermal protection relay operates the pump will be extremely hot. Touching the
pump in this condition may result in burns.
4.3 Starting in Cold Weather
Cold weather will increase the viscosity of bearing grease and harden diaphragms, resulting in
the pump being difficult to start. Follow the procedure below in such conditions.
1) Turn the switch ON/OFF 2~3 times with the inlet open to atmosphere until the pump starts.
If the pump still does not start, raise the ambient temperature to beyond 7°C.
2) With the inlet open to atmosphere, run the pump for a few minutes to warm it.
3) Commence normal operation once the pump has warmed.
5. Pump Performance
5.1 Pressure Achieved
The term “pressure achieved” as employed in the catalogue and in this manual is defined as
“the minimum pressure obtained by the pump without introduction of gas from the pump inlet
(i.e. the no-
load condition)”.
The manufacturer measures pump inlet pressure using a Baraton vacuum gauge (Absolute
Pressure Transducer 626A).
Note that the indicator values for pressure may differ between types of vacuum gauges.
The pressure achieved in practice is higher than that noted in the catalogue for the following
reasons.
1) The fact that the vacuum gauge is mounted a distance from the pump, the steam
generated by water droplets and rust etc on the inside walls of the pump and piping, and a
variety of gases present in the system result in increased pressure.
2) Leaks into the vacuum system introduce other gases, resulting in increased pressure.
5.2 Evacuation Rate
The rate of evacuation for diaphragm-type dry vacuum pumps varies with the type of gas
entering the inlet, and its pressure. The maximum rate of evacuation is reached when air is
introduced, and decreases slightly as pressure is reduced.
The resistance of the piping system increases with small bore piping which extends over long
distances, and this reduces the rate of evacuation.
The declared rate of evacuation for this pump is the maximum value achieved with dry air.
5.3 Power Requirements
The power required to drive the pump is the total of the work required to overcome the
rotational resistance of the pump (mechanical work), and the work required to compress the
air (compression work), and is at a maximum at an inlet pressure of 2.7 x 104 ~4 x 104 Pa. At
pressures below 500Pa, compression work is considerably reduced and power is expended in
mechanical work.
!
Caution
