Watson-Marlow 505LA - Manual (Page 4)

ATEX Directive: Watson-Marlow 505LA, 505LXA and 505LGA pumpheads User Manual 4
6 Installation guidelines
Please refer to the standard 505L manual (m-505l-gb-01) for general installation
instructions.
It is recommended that the chosen ATEX drive (motor/gearbox) is configured to
safely reach an overload condition before the 2.2Nm torque limit is reached. This
will prevent catastrophic failure of the rotor in the rare occurrence of a major
obstruction.
Particular attention should be given to the “Do’s and do not’s” section regarding
interfacing with suction and discharge tubing and/or pipework. It is important to
ensure proper connections are made to prevent leaks.
All ATEX pumpheads include provision for the prevention and dissipation of elec-
trostatic charge. In order to dissipate electrostatic charge effectively there must be
sufficient electrical contact between the pumphead and the suitably earthed drive.
It is imperative that the 505LA pumpheads are earthed by connecting the
earth terminal (circled in the photograph below) to earth (usually via a
suitable point on the pump drive).
It is possible to check the effectiveness
of any earth connection by measuring
its electrical resistance. To ensure
reliable dissipation of static the
maximum resistance to earth
should not exceed 1 MOhm.
Peristaltic tubing has limited
conductivity and so its use should
be limited to the length adjacent to
the pumphead. Electrostatic testing
and length of tubing limitations
have been used to determine that
Watson-Marlow tubing is compliant
with a II 2G IIB c T4 rating. Earthed,
conductive pipework should be used
elsewhere in the system.
5 Potential pump hazards
As part of the requirements of 94/9/EC all potential hazards, including expected
malfunctions, have been identified and subjected to a risk assessment. In order
to prevent these ignition sources becoming effective a number of changes have
been implemented (see Section 10). In addition to engineering modifications, the
changes include additional operating instructions in order to specify correct usage in
hazardous locations. Please refer to Sections 6-10 for further details.
Recognised ignition sources
Surface temperatures of rollers and tubing
Tube burst and subsequent spilling of pumped fluid
Mechanical failure of rotor hub
Exothermic and pyrophoric chemical reactions
Electrostatic charging of tubing and fluid
Bearing failure
Spring failure