To Achieve Ultimate Vacuum (If Gas Ballast Fitted); Pumps Already In Service; New Pumps, Pumps That Have Just Been Serviced Or Reconditioned, And Pumps That Have Been In Storage; To Pump Condensable Vapours (If Gas Ballast Fitted) - Edwards XDS 5 Instruction Manual

A726-01-880 Issue M
4.3

To achieve ultimate vacuum (if gas ballast fitted)

4.3.1

Pumps already in service

If the pumps have been switched off for some time it may be necessary to run for at least an hour on high flow gas-
ballast 'II' to purge the pump of condensable vapours (e.g. atmospheric water vapour).
Turn the gas ballast control to position '0' to achieve the best possible vacuum.
4.3.2 New pumps, pumps that have just been serviced or reconditioned, and pumps
that have been in storage
If the pump is new or has been in long term storage it may be necessary to run the pump on gas ballast to remove
atmospheric water vapour. This may take up to 24 hours depending on the storage conditions. Having run on gas
ballast, revert to gas ballast 0 condition (see
4.4

To pump condensable vapours (if gas ballast fitted)

Use gas-ballast (ballast knob set to I or II) when there is a significant proportion of condensable vapours in the process
gases. The pump should be up to full operating temperature prior to exposure to condensable vapours.
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 23
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 predicted 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 predicted 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 while within their explosive limits.
4.5.2

Flammable/pyrophoric materials

The following precautions and actions must be obeyed to ensure gas being pumped stays out of the
flammable range.
When flammable or pyrophoric materials are present within the equipment you must:
Not allow air to enter the equipment

Ensure the system is leak tight.

Page 22
Section 4.1) to achieve ultimate performance.
rd
March 1994 on the approximation of the laws of the
WARNING
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