3. ATEX certification
DANGER: INTERNAL EXPLOSION
The EDS dry pump is designed to pump gas and/or vapours. Ensure that the pump
temperatures are sufficient to prevent condensation forming which may otherwise lead
to corrosion and loss of explosion protection. The use of seal purges and correct warm-up
and shut-down procedures are necessary to prevent the formation of condensation. If in
any doubt, please consult Edwards.
Shaft-seal purge must be maintained in order to ensure long term reliability of shaft-seals
and the zoning/protection concept.
If blockages of the exhaust are possible, exhaust pressure should be monitored,
otherwise excessive back-pressure can occur, leading to high temperatures and risk of
explosion.
The EDS ATEX Category 3 dry pump uses the protection strategy of constructional safety for
internal atmospheres, and satisfies the requirements for ATEX Category 3.
Constructional safety relies on there being no ignition sources inside the pump. EDS dry
pumps are manufactured and tested to show that running clearances are maintained in the
pump during extremes of normal operation and at trip points of pump safety instruments.
For Category 3 inside pumps, ignition hazards are prevented from occurring in normal
operation. When using constructional safety as the protection concept ensure that no
process deposits are formed inside the pump which could potentially create an ignition
source. This can be achieved either by process control or by the use of solvent flush. In such
systems the solvent flush operation is safety critical and suitable safeguards must be put in
place to ensure that solvent flow is maintained to the prescribed regime. The gearbox of the
EDS pump is classified one zone lower than the pumping chamber; the high-integrity seal in
combination with seal purge ensures zone separation.
The EDS is capable of pumping a potentially explosive atmosphere that is likely to occur
occasionally in normal operation and therefore satisfies the essential requirements
identified in Annex II of the ATEX Directive 2014/34/EU for Category 3 equipment.
3.1 Classification and marking of the pump
The pump is marked as follows:
II 3/-G Ex h IIC T3 Gc
5 °C < Ta < 40 °C
(internal atmospheres only)
Modifying the supplied pump, voids the CE and ATEX Declaration of Conformity.
Table 1 Key to the Symbols
ATEX logo
h
The code letter “h” is valid for all non-electrical devices.
IIC
Explosion group
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A41802880_C - ATEX certification
