A540-55-880 Issue D
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Installation
3.5.1 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 Tool installation. The severity of the risks and
the necessary control measures will depend largely on whether the tool exhaust is in the flammable region, if this is
part of normal Process Tool 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 owing 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 user's responsibility to carry out a risk assessment and take appropriate measures:
Do not allow air to enter the equipment.
Ensure that the 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
LEL (lower explosive limit) or, if that is not practical, to below 60% LOC (limiting oxidant concentration).
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.
For further information, please refer to Semiconductor Pumping Application Guide (Publication no. P411-00-090) or
contact Edwards.
3.5.2 Gas purges
Gas purge is provided for the sole purpose of enabling the pumping of inert light gases such as helium.
3.6 Leak test the system
Note: If further information on leak testing is required, contact the supplier or Edwards for advice.
Obey the instructions and take note of any precautions given below to ensure that pumped gases
do not enter their flammable ranges.
The pumps are not suitable for use with hazardous production materials. Any hazardous
production materials must be diluted to a safe level before entering the pump.
Leak test the system after installation and seal any leaks found to prevent leakage of dangerous
substances out of the system and leakage of air into the system.
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