Watson-Marlow 604S/R, Installation And Operating Istructions, Page: 4 / 12

Page 4
Recommended operating procedures
DO keep delivery and suction lines as short as possible.
DO use the minimum number of bends in rigid pipe runs. If there must be a
bend, use a swept bend and not a tight elbow.
DO run at a slow speed when pumping viscous fluids. 9.6 or 12.7mm bore
tube with a 3.2mm wall will give best results. Tube smaller than this will
generate a high friction pressure loss which reduces the flow. Tube with a
larger bore will not have sufficient strength to restitute. Flooded delivery will
enhance pumping performance. Some tube materials are available with a
4mm wall for speeds up to 100rpm.(The rotor will require re-setting to a roller
track gap of 6.6mm.)
DO use suction and delivery pipelines with a bore equal to or larger than the
bore of the tube fitted in the pumphead. When pumping viscous fluids, the
losses caused by increased friction can be overcome by using pipe runs with
a cross sectional area several times greater than the pumping element.
DO use the largest possible bore tube running at slow speed for the longest
tube life.
DO fit an extra length of pump tube in the system so that you can move the
tube through the pumphead occasionally, without needing to break the
pumping circuit. This is particularly useful for extending tube life in long
running sterile applications.
DO keep the track and rollers clean, and ensure that the rollers are free.
DO NOT fit valves in the suction or delivery line without considering that
peristaltic pumps are self priming and will hold their prime up to several
metres, so there may be no need for non-return or foot valves, nor for the
loading valves required on many other kinds of pumps.
Any valves fitted must cause no restriction. If electrically actuated valves are
fitted, they should be interlocked so that the pump will only run when the
valves are open. Fit an automatic by-pass if manual valves are installed.
When using Marprene or Bioprene tubing , after the first 30 minutes of
running, re-tension the tube in the pumphead by releasing the tube clamp on
the delivery side a little and pulling the tube tight. This is to counteract the
normal stretching that occurs with Marprene and Bioprene, which can go
unnoticed and result in poor tube life.
Tube selection The chemical compatibility list published in the Watson-
Marlow catalogue is only a guide. If in doubt about the compatibility of a tube
material and the duty fluid, request a tube sample card for immersion trials.
Remember the sample will be fully immersed, but the fluid when in use will
only be in contact with the inside of the tube. If the material swells but does
not lose its strength it could be worth considering.
Viscous dispensing To overcome the common problems of reduced
accuracy and dripping delivery pipes, the suction and delivery lines should be
kept as short as possible. Use larger bore transmission tubing than that in the
pumphead to keep the friction losses to a minimum. Improved accuracy will
be noticed if rigid or semi-rigid pipe is used on the delivery side. The rigid tube
is effective in reducing over-run because it does not expand during pumping.