Flowserve Guardian Sealless Metallic - Manual (Page 56)

GUARDIAN USER INSTRUCTIONS ENGLISH 71569212 08-11
Page 56 of 68 flowserve.com
7 FAULTS; CAUSES AND REMEDIES
The following is a guide to troubleshooting problems with Flowserve Guardian G & H series pumps. Common
problems are analyzed and solutions offered. Obviously, it is impossible to cover every possible scenario. If a
problem exists that is not covered by one of the examples then refer to one of the books listed in section 10,
Additional sources of information or contact a Flowserve sales engineer or distributor/representative for
assistance.
FAULT SYMPTOM
Pump not reaching design flow rate
⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓ Pump not reaching design head (TDH)
⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓ No discharge or flow with pump running
⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓ Pump operates for short period, then loses prime
⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓ Excessive noise from wet end
⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓ Excessive noise from power end
⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓ Pump exhibits increased or higher than anticipated power consumption
⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓ Pump exhibits decreased or lower than anticipated power consumption
⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓
⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓
⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓ POSSIBLE CAUSES POSSIBLE REMEDIES
Insufficient NPSH. (Noise may not be
present.)
Recalculate NPSH available. It must be greater than the NPSH
required by pump at desired flow. If not, redesign suction piping,
holding number of elbows and number of planes to a minimum to
avoid adverse flow rotation as it approaches the impeller.
System head greater than anticipated.
Reduce system head by increasing pipe size and/or reducing
number of fittings. Increase impeller diameter. (note: Increasing
impeller diameter may require use of a larger motor.)
Entrained air. Air leak from
atmosphere on suction side.
1. Check suction line gaskets and threads for tightness.
2. If vortex formation is observed in suction tank, install vortex
breaker.
3. Check for minimum submergence
Entrained gas from process. Process generated gases may require larger pumps.
Speed too low. Check motor speed against design speed.
Direction of rotation wrong.
After confirming wrong rotation, reverse any two of three leads on
a three phase motor. The pump should be disassembled and
inspected before it is restarted.
Impeller too small.
Replace with proper diameter impeller. (NOTE: Increasing
impeller diameter may require use of a larger motor.)
Impeller clearance too large. Reset impeller clearance.
Plugged impeller, suction line or
casing which may be due to a product
or large solids. 1. Reduce length of fiber when possible.
2. Reduce solids in the process fluid when possible.
3. Consider larger pump.
Wet end parts (casing cover, impeller)
worn, corroded or missing.
Replace part or parts.
Not properly primed.
Repeat priming operation, recheck instructions. If pump has run
dry, disassemble and inspect the pump before operation.
Impeller rubbing.
1. Check and reset impeller clearance.
2. Check outboard bearing assembly for axial end play.
Damaged bushings, pump shaft,
thrust journals, or impeller.
Replace damaged parts.
Abnormal fluid rotation due to
complex suction piping.
Redesign suction piping, holding the number of elbows and planes
to a minimum to avoid adverse fluid rotation as it approaches the
impeller.
Magnetic coupling decoupled due to
excessive temperature or excessive
horsepower requirements.
1. Check process temperature to verify it’s within operating limits
of pump.
2. Check horsepower required by the process to verify it is within
the operating limits of the coupling size.
3. Replacement of the magnet assemblies may be necessary if
the magnets overheated and were permanently damaged. A static
torque test of the magnetic coupling may be necessary. Contact
your Flowserve representative for details.
Inner magnet rubbing bearing holder. Check for damaged or worn pump shaft and bushings.