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STP-H600/H1000 Series Instruction Manual
3.3.4 Vacuum Piping
DO NOT open the STP pump through the flange to atmospheric air while the
STP pump is running.
If atmospheric air flows into the STP pump, it may not function normally.
Depending upon the type of the auxiliary pump used, atmospheric air may
reverse flow into the STP pump when the auxiliary pump stops.
Attach a vacuum valve to the middle of the piping between the STP pump outlet
port flange and the auxiliary pump, and close the vacuum valve when the
auxiliary pump stops.
In order to let the STP pump bring its performance into full play, follow the
precautions below:
1) Be careful not to scratch the flange of the STP pump.
Before installing the STP pump, check whether or not there are scratches on
the surface.
2) Use steel or aluminum tubes with a low gas loss to connect the vacuum
equipment to the STP pump.
3) Take measures for minimizing leakage. It is also necessary to degrease the
tubes as regularly as possible to keep the gas loss as low as possible.
4) It is recommended to use an auxiliary pump of 240 L/min or more. However,
the pressure at the inlet and outlet ports varies with the flow rate of gas,
capacity of the vacuum equipment, length and material of the piping. Select
an auxiliary pump in accordance with the capacity and starting method
(simultaneous starting, starting after generating roughing vacuum) suitable for
the vacuum equipment you use.
5) Connect the STP pump and the auxiliary pump using stainless steel or
aluminum alloy tubing, flexible tubing, vacuum rubber or Teflon tubing, etc.
The following measures can be used to avoid the transmission of the vibration
of the auxiliary pump to the STP pump and the vacuum equipment.
· DO NOT place the auxiliary pump on the same floor as the vacuum
equipment.
· Locate the auxiliary pump on a vibration-proof table.
· Attain 1/3 or less of the rotational speed of the auxiliary pump, when
adjusting the inherent frequency of the auxiliary pump installed on a
vibration-proof table.
· Attach a weight to the piping from the auxiliary pump, or secure the piping
to a rigid, heavy object free of vibration.
· Use a tube of high flexibility.
6) Depending upon the type of the auxiliary pump used, oil vapor may
contaminate the inside of the STP pump. Some oil viscosity could cause a
malfunction when there is a strong reverse flow of oil.
Take the following measures to ensure the correct flow of oil:
· Attach a vacuum valve to the middle of the piping between the STP pump
outlet port flange and the auxiliary pump.
· Attach an absorption trap adjacent to the vacuum valve.
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