Watson-Marlow 501RLA, User Manual

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21 PB0346:m-501atex-en-03
WARNING! Do not run pumpheads at speed higher than the rated
maximum speed. This can lead to excessive roller and tubing
temperatures. Tube life will be reduced, increasing the chance of
premature failure.
When two or more items of ATEX equipment are combined, the permissible operating envelope will be
determined by the narrowest range after considering all values for a given parameter.
11 Tube life
A number of factors contribute to the life of the tubing:
Factors influencing tube life
Normal tube fatigue -dependent on tube size and material
Incorrect tube loading - see section 15 "501RLA Tube loading (Rotor and drive shaft do not freely
rotate)" on page 28 or section 14 "501RLA Tube loading (single pumphead installation)" on page 27.
Excess working pressure - see section 10 "Operating parameters" on the previous page
Chemical incompatibility - a table of tubing compatibility can be found on www.wmftg.com/chemical.
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:
Seesection 17 "Materials of construction" on page 35 for information on materials of construction.
Chemical reaction between pumped fluid and pump materials the materials of construction are listed
at www.wmftg.com/chemical.
Pumped fluid can be ignited by surface temperature of rollers - all Watson-Marlow’s ATEX equipment
has been rated as T4. (Meaning that even under worst-case operating conditions the maximum
surface temperature will not exceed 135C (275F)
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 50rpm. If low-flow, high-pressure operation is necessary, switching to a
smaller tube is recommended.