LEYBOLD RUVAC WH 2500, Инструкция по установке и эксплуатации

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Operation
59
130001398_002_C0 - 09/2016 - © Leybold
The permissible cut-in pressure depends on the ratio between the Roots
pump and the backing pump.
Δ
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:
Δ
p
max
p
E
~ ————
k
th
- 1
p
E
= Cut-in pressure
Δ
p
max
= Maximum permissible pressure difference
(see Technical Data)
k
th
=
Theoretical compression ratio
=
Nominal pumping speed
1)
RUVAC
Nominal pumping speed of the backing pump
k
eff
=
Effective compression ratio
=
Effective pumping speed RUVAC
Effective pumping speed of the backing pump
1) at the corresponding operating frequency
Example - Pump combination:
RUVAC WH 4400 at 50 Hz / SP 630
4400 m
3
· h
-1
k
th
= —————————
~
7
630 m
3
· h
-1
40 mbar
p
E
~
———————
~
6.5 mbar
7 - 1
With small vacuum vessels, the maximum permissible differential pressure
can be briefly exceeded (max. 3 minutes) upon start-up. If a pressure switch
has been installed, do not set it to this higher pressure because it will fail to
protect the pump against overload in the event of a greater gas quantity.
It is advisable to switch the RUVAC WH on and off via a pressure switch to
ensure that it runs only in the permissible pressure range. NOTICE