Watson-Marlow 620DuN and 620Du User Manual 15
9.2 Do’s and do not’s
Do not build a pump into a tight location without adequate airflow around the pump.
Do ensure that when the 620N watertight module is fitted the seals are intact and
properly located. Ensure that the holes for cable glands are properly sealed to main-
tain the IP66 / NEMA 4X rating.
Do not strap the control and mains power cables together.
Do keep delivery and suction tubes as short and direct as possible - though ideally
not shorter than 1m - and follow the straightest route. Use bends of large radius: at
least four times the tubing diameter. Ensure that connecting pipework and fittings
are suitably rated to handle the predicted pipeline pressure. Avoid pipe reducers and
lengths of smaller bore tubing than the pumphead section, particularly in pipelines
on the suction side. Any valves in the pipeline (not usually needed) must not restrict
the flow. Any valves in the flow line must be open when the pump is running.
Do use suction and delivery pipes equal to or larger than the bore of the tube in the
pumphead. When pumping viscous fluids use pipe runs with a bore several times
larger than the pump tube.
Do ensure that on longer tube runs at least 1m of smooth bore flexible tubing is con-
nected to the inlet and discharge port of the pumphead to help to minimize impulse
losses and pulsation in the pipeline. This is especially important with viscous fluids
and when connecting to rigid pipework.
Do site the pump at or just below the level of the fluid to be pumped if possible.
This will ensure flooded suction and maximum pumping efficiency.
Do keep the pumphead track and all moving parts clean and free from contamina-
tion and debris.
Do run at slow speed when pumping viscous fluids (though see Pressure advice in
9.1 General recommendations). Flooded suction will enhance pumping performance
in all cases, particularly for materials of a viscous nature.
Do recalibrate after changing pump tubes, fluid, or any connecting pipework. It is
also recommended that the pump is recalibrated periodically to maintain accuracy.
IP66 / NEMA 4X models may be hosed down, but should not be immersed. Protect
from prolonged UV exposure.
IP31 models may be wiped with a damp cloth, but should not be hosed or
immersed. The front of IP31 models is further protected against light spillages onto
the pump.
When using Marprene or Bioprene continuous tubing, do re-tension the tube
after the first 30 minutes of running.
Tube selection: The chemical compatibility lists published in Watson-Marlow pub-
lications are guides. If in doubt about the compatibility of a tube material and the
duty fluid, request a Watson-Marlow tube sample card for immersion trials.