Trouble Shooting - Johnson Pump TG GS2-25 Instruction Manual

3.20 Trouble shooting

Symptom
No flow
Pump not priming
Pump stalls or
irregular flow
Not enough capacity Pump speed too low
40
Cause
Suction lift too high
Air leak in suction line
Very low viscosity
Suction strainer or filter clogged
Pump casing incorrectly installed
after repair
Wrong direction of rotation of motor
Liquid level in suction tank falls too low
Output too high
Air sucking
Cavitation
Liquid vaporises in pump
(e.g. by heating up)
Air sucking
Cavitation
Back pressure too high
Safety relief valve set too low
Remedy
1 • Reduce difference between
pump and suction tank level.
• Increase suction pipe diameter.
• Reduce length and simplify suction pipe (use as
few elbows and other fittings as possible).
Also see section 3.18 Installation.
2 • Repair leak.
3 • Increase pump speed and reduce axial clearance
(see section 3.21 Maintenance instructions).
4 • Clear suction strainer or filter.
5 • Install pump casing correctly.
See section 3.18 Installation.
6 • For 3-phase drivers change 2 connections.
• Change suction and discharge opening.
(Attention! Check the location of the safety relief
valve).
7 • Correct liquid supply
• Provide a level switch
8 • Reduce pump speed/or install a smaller pump.
• Install by-pass line with check-valve.
9 • Repair leak in suction line.
• Check or replace shaft seal.
• Check/provide quench on shaft seal.
• Connect plug Bb to the pump discharge in order
to increase the pressure in the sealing box.
10 • Reduce difference between pump and suction
tank level.
• Increase suction pipe diameter.
• Reduce length and simplify suction pipe (use as
few elbows and other fittings as possible).
Also see chapter 3.18 Installation.
11 • Check temperature.
• Check vapour pressure of liquid.
• Reduce pump speed. If necessary install a larger
pump.
12 • Increase pump speed. Attention! Do not exceed
maximum speed and check NPSHr.
13 • Repair leak in suction line.
• Check or replace shaft seal.
• Check/provide a quench in the shaft seal.
• Connect plug Bb to the pump discharge in order
to increase the pressure in the sealing box.
14 • Reduce difference between pump and suction
tank level.
• Increase suction pipe diameter.
• Reduce length and simplify suction pipe (use as
few elbows and other fittings as possible).
Also see section 3.18 Installation.
15 • Check discharge pipe.
• Increase pipe diameter.
• Reduce working pressure.
• Check accessories (filter, heat exchanger, etc.).
16 • Correct pressure setting.
A.0500.501 – IM-TGGS/05.01 EN (03/2013)