Variant
Description
Overflow valve active
In the design with overflow valve, the weight-loaded valve plate
opens in the overflow valve when the maximum pressure differential
is exceeded, and it allows, depending on the gas accumulation, a
more or less large part of the in-coming gas to flow back from the
pressure side to the intake side. This protects the roots pump
against overloading and allows it to be switched on in the high pres-
sure range at the start of evacuation. During the pump down proc-
ess, if the pressure difference is undershot by the weight force of the
valve plate, the overflow valve closes again.
The roots pump can be switched on directly after the backing pump.
Overflow valve blocked
In the design with a blocked overflow valve, a drive with a frequency
converter can provide overload protection. If this is not present, the
roots vacuum pump must only be switched on when it has reached a
pressure at which the required gas quantity can be assumed by the
backing pump.
The blocking may not be canceled under any circumstances. As an
alternative, the optionally available ATEX-conform overflow valve
can be used.
Tbl. 1:
Variants
1.2 Target group
These operating instructions are aimed at all persons performing the following activities on the product:
● Transportation
● Setup (Installation)
● Usage and operation
● Decommissioning
● Maintenance and cleaning
● Storage or disposal
The work described in this document is only permitted to be performed by persons with the appropriate
technical qualifications (expert personnel) or who have received the relevant training from Pfeiffer Vac-
uum.
1.3 Conventions
1.3.1 Instructions in the text
Usage instructions in the document follow a general structure that is complete in itself. The required ac-
tion is indicated by an individual step or multi-part action steps.
Individual action step
A horizontal, solid triangle indicates the only step in an action.
► This is an individual action step.
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