Watson-Marlow 620U - Manual (Page 93)

Watson-Marlow 620UN, 620U, 620SN, 620S User Manual 93
27 620RE, 620RE4 and 620R
performance data
Pumping conditions
All performance figures in this operating instruction have been recorded against
peak pipeline pressures.
This pump is rated to 4 bar (58psi) peak pressure when fitted with a 620RE or
620RE4 pumphead using high-pressure tubing. However, it will generate in excess
of 4 bar (58psi) peak pressure if the pipeline is restricted. Where it is important that
4 bar (58psi) is not exceeded, pressure relief valves should be installed in the
pipeline.
Viscosity handling is maximised by using 4.0mm wall LoadSure elements with the
620RE and 620RE4 pumpheads.
Flow rates are normalised test values obtained using new tubing with the pumphead
rotating clockwise pumping water at 20C with negligible inlet and discharge
pressures. Actual flow rates achieved may vary because of changes in temperature,
viscosity, inlet and discharge pressures, system configuration and tubing perform-
ance against time. Flow rates may also vary due to normal manufacturing tolerances
of the tubing. These tolerances will make flow rate variance more pronounced at
smaller bore sizes.
For precise and repeatable performance it is important to determine flow
rates under operating conditions for each new piece of tubing.
620R family pumpheads' flow rates are directly proportional to rotor speed. If you
wish to run the pump at a speed not shown in the tables below, flow figures can be
reached by dividing the maximum flow shown in the tables below by the maximum
rpm figure, and multiplying the result by your required speed in rpm.
In normal circumstances, rotor and tube life are maximised if the pumphead is run
slowly, particularly when pumping at high pressure. However, to maintain
performance at pressures above 2 bar, avoid running the pumphead below 50 rpm.
If low-flow, high-pressure operation is necessary, switching to a smaller tube is
recommended.
Sta-Pure and Marprene TM tubing are hard to compress when new. When using
tubing made of these materials, the first five pumphead revolutions should be at a
speed of 10rpm or greater. If the pump is run slower, the safety system built into
pump drive’s software may cause it to stop and display an over-current error
message.
Note: Flow rates quoted have been rounded for simplicity, but are accurate to with-
in 5% - well within the normal tubing tolerance variation of flow rate. They should
therefore be taken as a guide. Real flow rates in any application must be determined
empirically.