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Original document - Mi-503 EN Edition: 2022-06
2.5 Pneumatic actuators type A, ATEX
Actuators type A, with additional type indication -E, is in compliance with the
ATEX-directive 2014/34/EU.
The actuator has the following Ex-marking: II 2 GD Ex c X
II Equipment group II (not mines)
2 Equipment category 2, for use in zone 1 and 2 (gas atmospheres) and
zone 21 and 22 (dust atmospheres)
G Permitted to use in gas atmospheres
D Permitted to use in dust atmospheres
Ex c Ignition protection according to the standard for mechanical
products “constructional safety”
X Special conditions for SAFE use is available in the ATEX-instruction and
in the “declaration of conformity”
Use stainless steel tubing to connect the actuator to the positioner or the solenoid
valve.
Make sure there is electrical contact between the actuator, the valve and all
associated equipment, as well as between all components in the actuator during
repair or assembly (resistance max. 1 MΩ).
Brackets of unpainted stainless steel or the Somas mounting block are to be used
for mounting of associated equipment on top of the actuator.
Brackets of unpainted stainless steel are to be used for mounting of actuators on
valves.
The valve must be connected/earthed to the pipeline.
To avoid charging and electrostatic discharges: Do not clean the Somas logotype
stickers and the red warning stickers with dry fabrics.
2.5.1 Special conditions
For actuators including spring packages, the spring packages shall be replaced by
new ones every fifth (5) year or two (2) million operating cycles, whatever comes
first.
As an alternative the spring package replacements can be avoided by connecting
both air connections, CLOSE and OPEN, on each actuator cylinder, to the valve
positioner or the solenoid valve. The function of the valve positioner and the
solenoid valve must be double-acting type. As an alternative to double-acting
positioners and solenoid valves, other equipment can be used, with such function
to permanently ensure instrument air only, on both sides of the pistons in the
actuator cylinders. The supply air must be clean and dry instrument air and have
a constant pressure within the range of 4-8 bar (0,4-0,8 MPa).
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