Install valves to shut off (Lockout / Tagout) purge gas N
2
and cooling water.
When stopping the backing pump, atmospheric air can flow reversely into the STP pump, depending
on the backing pump.
Attach a vacuum valve to the pipe between the STP pump outlet port flange and the backing pump.
Close the vacuum valve when stopping the backing pump.
Note: Some noise or detecting "Disturbance error" can happen on the STP pump when vacuuming
with the backing pump. Because the rotor in the STP pump is sucked by the backing pump,
depending on the backing pump's speed, chamber capacity, and pipe length between the
STP pump and the backing pump. When the failure is detected, perform the RESET
operation.
Follow the below to let the STP pump work on its original performance:
1. Be careful not to scratch the flange of the STP pump and the vacuum equipment. Before
installing the STP pump, check them for no scratches on the surface.
2. Use a low gas loss tube such as made of steel or aluminium tubes to connect the vacuum
equipment and the STP pump.
3. Leaks should be minimised as possible. It is also necessary to degrease the tubes to keep gas
losses as low as possible.
4. For a recommended backing pump's speed, refer to Section 2.1, "STP pump specifications".
However, the pressure at the inlet and outlet ports varies with the gas flow rate, the vacuum
equipment's capacity, length and material of the piping.
Select a backing pump by its capacity and starting method (such as simultaneous starting or
starting after generating roughing vacuum) suitable for the vacuum equipment.
5. Depending on the type of backing pump, oil vapour can contaminate the inside of the STP pump.
The viscosity of some kind of oil can cause a malfunction when the reverse flow of oil is strong.
Take the following measures to ensure the correct flow of oil:
• Attach a vacuum valve to the pipe between the STP pump outlet port flange and the backing
pump.
• Attach an adsorption trap next to the vacuum valve.
3.5.1 Vacuum piping method
1. Attach the inlet port to the high vacuum side.
(Refer to Section 2.1, "STP pump specifications" for maximum working pressure).
2. Attach the outlet port to the inlet port flange of the backing pump (primary side pump).
(Refer to Section 2.1, "STP pump specifications" for allowable backing pressure).
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