Operation
37
GA03108_002_C1 - 04/2018 - © Leybold
4 Operation
4.1 Start-up
Check the pump motor’s direction of rotation (see Section 3.4)
RUVAC WSU
The RUVAC WSU can be started together with the backing pump at atmos-
pheric pressure.
It is protected against excessively high pressure differentials by a bypass line.
The opening pressure of the differential valve is designed only for 50 or 60
Hz operation of the pumps.
RUVAC WS
Do not switch on the RUVAC WS until the backing pump has evacuated the
vacuum vessel to the cut-in pressure.
For processes in which condensable vapors are pumped, it is advisable to
evacuate the vacuum vessel via a roughing line to the cut-in pressure.
Electrically switch on the Roots pump together with the backing pump and
cut it in upon reaching the cut-in pressure. The initial bypassing of the Roots
pump serves to prevent condensation of vapors in the cold pump.
The permissible cut-in pressure depends on the ratio between the Roots
pump and the backing pump.
∆p
max
p
E
= ————
k
eff
- 1
Since k
eff
is not known in all cases, the following equation may be used for a
first approximation:
:
∆p
max
p
E
~ ————
k
th
- 1
p
E
= Switch-on pressure
∆p
max
= Maximum permissible pressure difference (see Technical Data)
k
th
= Theoretical compression ratio =
k
eff
= Effective compression ratio =
Example - Pump combination:
RUVAC WS 501
2)
/ Sogevac SV 100
505 m
3
· h
-1
k
th
= ————————
~
5
100 m
3
· h
-1
1)
at the corresponding operating frequency
2)
at 50 Hz operation
NOTICE
NOTICE
Nominal pumping speed
1)
RUVAC
Nominal pumping speed of the backing pump
Effective pumping speed RUVAC
Effective pumping speed of the backing pump
80 mbar
p
E
~
———————
~
20 mbar
5 - 1
