M588-00-880 Issue E
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Installation
3.4 Connect the purge gas supply
Ensure that the purge gas supply conforms to the requirements given in the technical data section. Failure to
do so may cause the gas pipelines to become blocked or the dry pumping system to be damaged.
Refer to Figure 3, item 18 for location of the purge gas connection. Nitrogen and clean dry air are suitable purge
gases for GXS dry pumping systems. To use a different purge gas, please contact Edwards.
Check visually that the rotameter is not damaged when installing the dry pumping system.
Note: Refer to Section 2.4 for purge gas supply requirements.
3.4.1 Flammable / pyrophoric materials
When flammable or pyrophoric materials are present within the pump there may be additional risks that the user is
responsible for assessing and managing as part of the entire process system installation. The severity of the risks and
the necessary control measures will depend largely on whether the process system exhaust is in the flammable
region, if this is part of normal operation, or if it might only occur under rare conditions. The additional risks arise
because all dry pumps must be considered a potential source of ignition due to the heat of compression, or possibly
friction. If ignition occurs then the following may happen:
High pressures could occur within the pump and may not be contained.
A flame front could travel back up the foreline.
A flame front could travel downstream from the exhaust of the pump.
Industry best practice suggests that the following measures will reduce the risks of pumping flammable mixtures and
pyrophoric materials, but it is the responsibility of the user to carry out a risk assessment and take appropriate
measures:
Do not allow air to enter the equipment.
Ensure that the dry pumping system is leak tight.
Ensure that gases in the pump do not enter the flammable range. This may be achieved by diluting gases in
the pump by supplying sufficient inert gas purge. For example, dilution with nitrogen to below one quarter
Lower Explosive Limit (LEL) or, if that is not practical, to below 60% Limiting Oxidant Concentration (LOC).
The gas module supplied with the pump is not intended to perform a safety function. Users may need to
consider adding appropriate measures to monitor the flow of purge gas, for example external sensors. Dry
pumping systems that are fitted with the light duty gas module must not be used on applications pumping
flammable or pyrophoric materials.
For further information please refer to Publication Number P400-40-100, Applications Note 'Pumping Flammable
Gases' P411-00-090 or contact Edwards.
Obey the instructions and take note of any precautions given below to ensure that pumped gases
do not enter their flammable ranges.
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