ATEX Directive: Watson-Marlow 800 series pumps and pumpheads User Manual
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6. Installation guidelines
Please refer to the standard 800 series manual (800-gb-01.pdf) for general
installation instructions.
All ATEX pumpheads include provision for the prevention and dissipation of
electrostatic charge. In order to dissipate electrostatic charge effectively there must
be sufficent electrical contact between the pumphead and the suitably earthed drive.
It is imperative that the 800 series pumpheads are earthed by connecting
the earth terminals (seen in the photograph below) to earth (usually via a
suitable point on the pump drive, as seen here).
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 specifiy 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
Mechanical impact following incorrect maintenance
Exothermic and pyrophoric chemical reactions
Electrostatic charging of tubing and fluid
Bearing failure
Spring failure
It is possible to check the effective-
ness of any earth connection by
measuring its electrical resistance.
The resistance from any point on the
guard to the earth terminal is
typically 25 Ohms.
To ensure
reliable dissipation of static the
maximum resistance to earth
should not exceed 1 MOhm.
It is also imperative that appropriate
over-pressure protection is designed
into the installation of the pump. This
will ensure that the safe operating
limits of the pump are not exceeded
in the event of a blockage.
Peristaltic tubing has limited conductivity and so its use should be limited to the length
adjacent to the pumphead.