Pump Will Not Prime; Leakage At Tubing; Failure To Run; 3. Troubleshooting - Milton Roy LMI P1 Basic Manual

IV – 3. TROUBLESHOOTING

Pump will not prime

•
Pump not turned on or plugged in.
Turn on pump/plug in pump.
•
Output dials not set properly.
Always prime pump with speed at 80 % and stroke
at 100 %.
•
Foot valve not in vertical position on bottom of tank.
See Chapter II – 1. Section Foot valve/ceramic
weight.
•
Pump suction lift too high.
Maximum suction lift is 1,5 m. Pump with High
viscosity liquid handling assemblies require flooded
suction.
•
Suction tubing is curved or coiled in tank.
Suction tubing must be vertical. Use ceramic weight
supplied with pump. (see Chapter II – 1. Section
Foot valve/ceramic weight).
•
Fittings are over tightened.
Do not overtighten fittings. This causes seal rings to
distort and not seat propertly which causes pump to
leak back or lose prime.
•
Air trap in suction valve tubing.
Suction tubing should be as vertical as possible.
AVOID FALSE FLOODED SUCTION (see Chapter
II – 1. Section Flooded suction).
•
Too much pressure at discharge (pump without 4-
function valve).
Shut off valves in pressurized line. Disconnect
tubing at injection check valve (see Chapter III – 1.
Priming). When pump is primed, reconnect
discharge tubing.
Pump loses prime
•
Solution container ran dry.
Refill container with solution and reprime (see Part
III).
•
Foot valve not in vertical position on bottom of tank.
See Chapter II – 1. Section Foot valve/ceramic
weight.
•
Pump suction lift too high.
Maximum suction lift is 1,5 m. Pump with High
viscosity liquid handling assemblies require flooded
suction.
•
Suction tubing is curved or coiled in tank.
Suction tubing must be vertical. Use ceramic weight
supplied with pump. (see Chapter II – 1. Section
Foot valve/ceramic weight).
•
Fittings are over tightened.
Do not overtighten fittings. This causes seal rings to
distort and not seat propertly which causes pump to
leak back or lose prime.
•
Air trap in suction valve tubing.
Suction tubing should be as vertical as possible.
AVOID FALSE FLOODED SUCTION (see Chapter
II – 1. Section Flooded suction).
LMI, Doseur à membrane, L001, Rev.B, 1098
•
Air leak on suction side.
Check for pinholes, cracks. Replace if necessary.

Leakage at tubing

•
Worn tubing ends.
Cut tubing about 25 mm (1'') off tubing and then
replace as before.
•
Loose or crack fitting.
Replace fitting if cracked. Carefully hand tighten
fittings. Do not use pipe wrench. Once fitting comes
into contact with seal ring, tighten an additional 1/8
or ¼ turn.
•
Worn seal rings.
Replace balls and seal rings (see part IV).
•
Solution attacking Liquid handling assembly
material.
Consult Technical Assistance Department for
alternate materials compatible with the pumped
solution.
Low output or failure to pump against
pressure
•
Pump's maximum pressure rating is exceeded by
injection pressure.
Injection pressure cannot exceed pump's maximum
pressure. See pump data plate.
•
Worn seal rings.
Replace them : see Chapter IV –1.
•
Ruptured diaphragm.
Replace diaphragm : see Chapter IV –1. Section
Diaphragm replacement.
•
Incorrect stroke length.
Check zero on pump/Re-zero pump (See Chapter
IV – 2.).
•
Tubing run on discharge may be too long.
Longer tubing runs may create frictional losses
sufficient to reduce pump's pressure rating.
•
Clogged foot valve strainer.
Remove foot valve strainer when pumping slurries
or when solution particles cause strainer to clog.

Failure to run

•
Pump not turned on or plugged in.
Turn on or plug in pump. Check also programming
(A9, B9, C9 Series).
•
EPU failure.
Disassemble pump and measure the resistance of
the EPU across the EPU wires. Resistance reading
should be in accordance to the table (see Chapter
IV – 4.). Also check EPU leads to ground.
•
Pulser failure.
The pulser should be replaced if EPU checks out
OK.
IV - 3