Edwards ATEX 1 EHR, Instruction Manual

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INSTALLATION
A750-04-880 Issue F
3.3 Use of flammable sealing/seals flush liquids: ATEX Category 1, 2
and 3 pumps
Small amounts of the sealing/seals flush liquid can leak out from the mechanical shaft seals into the bearing housing.
If you use a flammable sealing liquid in the pump, the atmosphere inside the pump will become saturated with a
flammable vapour.
If oxygen or air is introduced into the pump, it is possible for the internal atmosphere to become potentially
explosive, independently of the flammability of the pumped process gases/vapours. This could cause the flammable
zone inside the pump to be different from the flammable zone in the process pipelines.
To ensure that the flammable zone inside the pump is not changed, you must:

Ensure that the system is leak tight: refer to Section 3.16 .

After each process pumping cycle, use an inert gas purge to vent the system to atmospheric pressure. This
will ensure that when the next evacuation cycle is started, the oxygen concentration is either 2% by volume
below the limiting oxygen concentration or 60% of the limiting oxygen concentration if it is less than 5% by
volume.
3.4 Pumping system design
3.4.1 General

The gases to be pumped must not contain particles larger than those specified in Table 2 . If necessary,
incorporate an inlet filter in the inlet pipeline to the pump, to prevent the ingress of solids into the pump.

Make sure that the process outlet pipeline cannot become blocked. If you have an outlet-isolation valve,
make sure that you cannot operate the pump with the valve closed.

Install a non-return valve in the inlet pipeline, to prevent the reverse-flow of sealing liquid into your system
when the pump is switched off.

Provide for a purge of inert gas when you shut down the pumping system, to dilute dangerous gases to safe
concentrations.

Design your pumping system such that, if it is shut down automatically, it cannot restart automatically
without being reset manually.
3.4.2 Oxygen monitoring: ATEX Category 2 and 3 pumps only
If you use a flammable sealing liquid or a flammable seals flush liquid and you cannot carry out a pressure rise test
to determine the leak tightness of the system (see
Section 3.16 ), your pumping system must be configured so that
the oxygen concentration at the process outlet is constantly monitored.
If an oxygen concentration exceeding the values specified in Section 3.3 is detected, your system must be configured
to:

Introduce an inert gas into the system to reduce the oxygen concentration,
or:

Shut down the pump.
WARNING
Obey the safety instructions listed below and take note of appropriate precautions when you
install the pump.