Edwards xds35i User Manual

A730-01-880 Issue E
Page 16 © Edwards Limited 2007. All rights reserved.
Edwards and the Edwards logo are trademarks of Edwards Limited.
Operation
4.3 To achieve ultimate vacuum
In order to achieve the best possible vacuum, the pump should be operated with the gas ballast control on position
'0'. However, if the pump, or elements of the vacuum system it is attached to, are new or have been newly fitted,
some atmospheric moisture may be present. If atmospheric moisture is present, run the pump with the gas ballast
control in position 'I' or 'II' for 20 minutes before switching to position '0'. If moisture is allowed to remain, the
performance of the pump will be impaired.
4.4 To pump condensable vapours
Select a suitable gas ballast setting (gas ballast control in position 'I' or 'II') when there is a high proportion of
condensable vapours in the process gases. This will assist the vapours to pass through the pump without condensing
and keep the pump performance from degrading.
4.5 Implication of ATEX directive
4.5.1 Introduction
This equipment is designed to meet the requirements of Group II Category 3 equipment in accordance with Directive
94/9/EC of the European Parliament and the Council of 23rd March 1994 on the approximation of the laws of the
Member States concerning equipment and protective systems intended for use in potentially explosive atmospheres.
(The ATEX Directive).
The ATEX Category 3 applies in respect of potential ignition sources internal to the equipment. An ATEX Category has
not been assigned in respect of potential ignition sources on the outside of the equipment as the equipment has not
been designed for use where there is an external potentially explosive atmosphere.
There is no potential source of ignition within the pump during normal operation but there may be potential sources
of ignition under conditions of foreseeable and rare malfunction as defined in the Directive. Accordingly, although
the pump is designed to pump flammable materials and mixtures, operating procedures should ensure that under all
normal and reasonably foreseeable conditions, these materials and mixtures are not within explosive limits. Category
3 is considered appropriate for the avoidance of ignition in the case of a rare malfunction which allows flammable
materials or mixtures to pass through the pump whilst within their explosive limits.
4.5.2 Flammable/pyrophoric materials
When flammable or pyrophoric materials are present within the equipment you must:
z Not allow air to enter the equipment.
z Ensure the system is leak tight.
z Dilute any flammable gases or vapours by using an inert purge (e.g. N2) to the pump inlet and/or gas purge
to reduce their concentration the pump and exhaust line to less than one quarter of their published lower
explosive limits (LEL).
z Prevent the condensation of flammable vapours within the pump mechanism and exhaust line by using an
inert gas purge to the pump gas ballast connection.
4.5.3 Gas purges
CAUTION
The following actions must be taken to ensure that the gas being pumped stays out of the flammable range.
The inert gas purge should be switched on to remove air from the pump and exhaust before the process starts. The
purge flow can be switched off at the end of the process only after any remaining flammable gases or vapours have
been purged from the pump and exhaust line.

Edwards xds35i Specifications

General

Brand	Edwards
Model	xds35i
Category	Water Pump
Language	English