7 Shaft seal of the pump
Shaft seals are present only on the discharge side of the pump’s
rotors. The two shaft seals are non-contacting owing to a combination
of piston ring and labyrinth seals, but are not hermetically tight. The
seal in the direction of the atmospheric side and in the direction of the
gear chamber is vented.
In the case of a low pressure in the discharge line there is the risk of
adding small quantities of air via the shaft seal to the process gas.
When the discharge pressure on the process gas side exceeds atmos-
pheric pressure, small quantities of processed gas can escape into the
gear housing and also to the outside.
In order to prevent any process gas from escaping from the pump
chamber, use purge gas for the shaft seal. The purge gas will reliably
prevent any leaks between the gas chamber and the surroundings
provided the correct quantity of purge gas is used within the specified
limits.
Please consult us first when planning such an application.
8 When the pump has been used to pump harmful media before, intro-
duce corresponding safety precautions before opening the intake or
the discharge connections. Before opening the pump, purge it for a
longer period of time with an inert gas. If necessary, wear gloves,
breathing protection or protection clothing and work under a fume
hood. Firmly seal off the pump. When shipping the decontaminated
pump for servicing please also indicate the type of hazard. For this see
Section 5.7 Service at Leybold.
When shipping contaminated pumps which require approval by the
authorities, note the applicable regulations regarding packaging and
shipping.
9 In special cases the composition of these substances may be relevant
to safety. In these cases, the user must carefully review the effect of
these substances and introduce suitable personnel protection meas-
ures.
You must also expect the gas to have a different composition at the
inlet compared to the discharge. This must be included in the assess-
ment of potential hazards.
10 In case of a malfunctioning pump, in particular because of a blocked
discharge line or seized rotors due to hard deposits or foreign objects,
the possibility of leaks in the casing cannot be ruled out. When pump-
ing harmful gases, the operator must ensure that such a malfunction
cannot occur, respectively that leaks at the pump will not be a hazard.
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