ATEX Directive: Watson-Marlow 800 series pumps and pumpheads User Manual
5
Where there is potential for the pumped fluid to become charged through pumping,
protective measures should be implemented at the discharge outlet to dissipate this
charge safely.
It is recommended that the chosen ATEX drive (motor/gearbox) is configured to safely
reach an overload condition before the 135Nm torque limit is reached. This
will prevent catastrophic mechanical failure in the rare occurrence of a major
obstruction.
Note
: Tube contact with polyamide materials such as nylon should be avoided.
7. Tube life
Only Watson-Marlow tubing should be used to guarantee continued compliance with
the ATEX directive.
A number of factors contribute to the life of the tubing:
Factors influencing tube life
Normal tube fatigue - dependent on tube size, material and
pumphead speed
Incorrect tube loading - see the 800 series manual
(800-gb-01.pdf) for guidance
Excess working pressure - see Section 4 Operating parameters
Chemical incompatibility - a table of tubing compatibility can be
found on http://www.watson-marlow.com/wmb-gb/p-chem-a.htm.
Immersion kits are available from Watson-Marlow for testing.
For each application it is strongly recommended that tube life should be determined
by trials, prior to installation in a hazardous environment. If this is not possible,
or if there is any doubt in terms of tube life then the following hazards should be
recognised before installing a pump in a potentially explosive atmosphere:
Chemical reaction between spilled pumped fluid and pump
materials - the materials of construction are listed in Section 9
Spilled, pumped fluid could be ignited by the surface temperature
of the rollers - Watson Marlow’s 800 series pumpheads have been
rated as T4 (meaning that even under worst-case operating
conditions the maximum surface temperature will not exceed
135C)
WARNING: The tube connectors are isolated metal parts and have no
path to earth via the pumphead. 800 series ATEX pumps are designed to
be connected into conductive metal piping systems, where static charge
on the tube connectors is dissipated via the pipe system earthing
arrangement. If the pump is used in a system with non-conductive pipes
or connections, the user will need to make provision for earthing the
tube connectors to ensure dissipation of any static charge.