Bauer Magnum SM 540 Operating Manual page 26

CAUTION ! If priming takes longer than 60 to 90 secons, some points need checking:
7.1. Check if suction line is tight (rubber sealing ring, gaskets and hoses)
7.2. Check the delivery line valve
7.3. Inspect compressor hoses and sealings
7.4. Check if the ball got stuck in the branch line / trap
7.5. Ball cock not closed in the branch line / trap
7.6. Check if compressor lamellas are blocked (compressor overheated – this can only happen after very long
continuous operation or if the pump is soiled.
7.7.
Defective mechanical seal
When priming is completed, fill up the pipeline by slowly opening the delivery line valve (close the ball cock to
the compressor).
CAUTION ! If the delivery line is very large-dimensioned or if the valve is opened quickly at simultaneously
increasing speed (no counter-pressure builds up), the pump very quickly starts cavitating. In this condition seal
damage is very likely in short time.
Also note that at low speed with the valve open, the pump always remains in critical operating condition
(cavitation) if only the speed is increased without counter-pressure.
When large pumping systems are involved, the entire system must first be filled with the valve half-closed and
then the required oprating condition must be established by speed increse and adjustment of the valve.
Except during suction with mechanical self-priming unit – pumping against the closed valve is forbidden.
Note also: the higher the dry matter content, the lower the suction height (suction capacity).
Bigger sized suction lines and smaller drive speeds have a positive affect to the entire pumping operation.
The suction capacity of the evacuating pump is sufficient for filling the suction line inspite of minor leaks (rubber
ring with a small crack), but the centrifugal pump is unable to build up pressure because the suction flow breaks
off due to the air leak.
This problem cannot be solved by increasing the drive speed.
Increasing the speed of a pump not working (suction flow break-off) increases the danger of dry run and
subsequent seal damage.
Never exceed the maximum driving speed indicated on the nameplate.
Higher driving speeds increase the circumferential speed at the mechanical seal and the ensuing heat build-up
to such an extent that thermal stress cracking or insufficient seal face lubrication are caused.
When the pump performance time is very long, check the gearbox temperature (should not be higher than
90°C).
Rinse and clean the pump after every use.
Conveying viscous fluids
With increasing viscosity (viscous fluids) of the pumped fluid at a constant speed, the output and discharge head
decrease at increasing power absorption. The summit of the descenting effeciency curve moves to the left – as
shown on the diagramme.
Besides, the pump is more sensitive to reduced output and to breaking the output if the share of viscous fluids
in the pumping medium grows.
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Operating manual for BAUER gear pump