Leybold vacuum SC 15 D, Operating Instructions Manual, Page: 28 / 40

Operation
28
GA01423_0102 - 11/2004
Caution
Proceed as follows to start the pump:
1. Close the isolation valve to prevent drawback of debris from the vacu­
um pump into vacuum chamber. (Open the purge valve if one is instal­
led).
2. Switch the vacuum pump ON.
3. Open the isolation valve (close purge valve if one is installed) and pump
the vacuum chamber.
3.2 Pumping
Operating the pump continuniously near its ultimate pressure (for example,
backing a turbomolecular pump) can cause deposits of foreign matter or
moisture in the pump resulting in failure.
Operate with the Air Flush open (see below), or close the isolation valve and
open the purge valve for 3-5 seconds to atmosphere several times once a
day to remove foreign matter from inside the pump.
Operate at designated temperature
When pumping vapor, the inlet gas temperature must be Iess than 50 °C.
When vapor temperature is more than 50 °C, install a chiller or trap in the
piping between the vacuum chamber and the pump to reduce the inlet
vapor temperature to less than 50 °C. Pumping vapor of over 50 °C can
cause failure.
3.3 Pumping vapor
(air flush operation)
When pumping vapor, open the Air Flush Port. If you pump vapor
with the Air Flush Port closed, condensed moisture remains in the
pump, resulting in failure.
Use care to avoid damaging the Air Flush Port (especially the air
muffler).
When the Air Flush is open, noise level and ultimate pressure
increases.
Purpose of Air Flush
The moisture volume drawn into pump varies depending on the tempera­
ture and pressure in the chamber. Pumping humid gas can result in moi­
sture condensing in the pump. This remaining moisture can cause deterio­
ration of the ultimate pressure or pump failure. When the vacuum chamber
contains gas with humidity of over 60 % RH, the pump must be operated
with the Air Flush open. Operating the pump with the Air Flush open remo­
ves the moisture which allows the pump to reach its ultimate pressure.