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Frequently Asked Questions
Q - What precautions should be taken when handling
abrasive slurries?
A - Select a large pump, running at low speed. The
circumferential speed of the rotor is very important, to minimise
wear between rotor and casing use a hardened casing to create the
best possible wear resistance, together with rotor materials that
can withstand the abrasion.
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Q - What precautions should be taken when handling
high viscosity fluids?
A - Make sure that the pump will be filled up. This is
achieved by selecting a pump with large ports, which allows the
fluid to fill the pump chambers. Running the pump at low speed
gives the fluid enough time to enter the pump chambers.
If a satisfactory degree of filling can not be
obtained by gravity or pressuring the fluid source tank, an in-feed
screw may be required.
Install the pump as close as possible to the fluid
source, avoiding unnecessary restrictions.
If these issues are not addressed, the pump may
cavitate which will increase wear and may inflict damage to the
pump.
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Q - Can the pump withstand dry running?
A - The lobe pump may dry run, as there is no physical contact
between rotors and casing. The seal chamber is filled with a
lubricant, that will not let the seals dry run, but keep them
lubricated at all times. Further to this the lubricant will
transmit heat generated away from the seals.
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Q - How can I minimise the pressure drop?
A - Use long elbows, and large diameter pipes.
Use as few elbows as possible. In certain cases lubricants can
be added to the fluid, thereby decreasing the pressure drop.
One should remember that the pipe system is a
one-time cost - the increased running cost caused by high pressure
is a continuous cost through the complete life span of the pump.
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