Johnson Pump MDR Series Instruction Manual page 20

Problem
Leakage from pump
body
Shaft break
Magnet housing
damage
Impeller damage
Impeller deformation
20
Possible cause
Loose pump body screws
Wrongly installed O-ring
Damaged O-ring
Dry running, thermal-shock,
running against closed
valve, shock at
handling, corrosion
Short of head
Dry running, excessive
wear, running against closed
valve, corrosion
Short of head
Excessive wear, corrosion
Excessive temperature
Excessive temperature vs
system pressure
Remedy
Tighten screws
Replace O-ring
Replace O-ring
Make sure that the material
is resistant to the media
Replace shaft
Make sure that the material
is resistant to the media
Increase discharge head
(see section 2.3)
Replace magnet housing
Make sure that the material
is resistant to the media
and that no dry running will
occur
Increase discharge head
(see section 2.3)
Replace impeller
Make sure that the material
is resistant to the media
Replace impeller (see
section 2.5)
Replace impeller (see
section 2.6)
MDR/EN (0909) 1.0