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Doc. ISM0076_MANUALE_CN SEAL-MV_ENG_REV04.DOCX
The head requested is lower than pump
head expected.
Increase the diameter of the discharge pipe.
Replace the pump.
Consult
M PUMPS PROCESS
.
Insufficient speed
Consult
M PUMPS PROCESS
.
Excessive Suction lift
Check that NPSHa>NPSHr, suction line losses on
strainer and fittings
The pump rotates in the opposite
direction.
Check the direction of rotation.
Refer to section 13.5 of this manual
Air or steam trapped in the suction
.
Check the presence of air or steam trapped. Check
suction line design.
Air leaks in the suction line
Check suction pipe is airtight
Air leaks into pump through mechanical
seal, sleeve joints, casing joint or pipe
plugs
Check and replace with new all damaged or worn parts,
consult
M PUMPS PROCESS.
Foot valve undersized or partially
clogged
Check foot valve.
Suction pipe inlet not sufficiently
submerged
Consult system designer
The liquid contains air or steam. The
liquid produces foam.
Check the presence of vortices in the suction line. Enter
some in the fuel tank to prevent the formation of
vortices. Install a tank of sufficient capacity in the
suction line to allow gas to drag
.
Insufficient inlet pressure, with the
generation of cavitation and loss of
efficiency.
Increase the static height at the suction
.
Check that the intake is not blocked or are no
bottlenecks. Reduce the liquid temperature. Increase the
diameter of the intake pipes.
Reduce the length of inlet pipes. Open completely the
inlet valve. Check the viscosity of the liquid; refer to
"technical data" section of this manual, increase the
temperature of the liquid if necessary.
Wear ring, wear pump casing or
impeller.
Check the condition of rotating ring wear and collar.
Replace if worn; refer to Chapter 10 of this manual.
The temperature of the liquid is close to
boiling point
Reduce the liquid temperature.
Viscosity of liquid different from design Consult
M PUMPS PROCESS.
NO FLOW
Causes
Remedies / actions
The pump is defused
Re-prime the pump. Refer to section 13.3 of this
manual. Check for air leaks in the suction line
Suction line blocked
Ensure that there are no blind pipes, obstructed or
valves closed.
Excessive Suction lift
Check that NPSHa>NPSHr, suction line losses on
strainer and fittings
