Watson-Marlow 700 series - Manual (Page 5)

ATEX Directive: Watson-Marlow 700 series pumpheads User Manual 5
6 Installation guidelines
Please refer to the standard 701R manual (PB0230) for general installation instruc-
tions.
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 701RA pumpheads are earthed by connecting the
earth strap to a suitable point on the drive - usually through the bolts/feet
of the gearbox or directly onto the baseplate.
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 rating. Earthed, conductive pipework should be used elsewhere in
the system.
Self Priming: The pump can be run dry to facilitate self priming. However excessive
periods of dry running will reduce tube life. The temperature of the rollers and tubing
will increase during dry running. Tests have shown that this increase in temperature
will not affect the T4 temperature rating.