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A.0500.301/314.C – IM-TW/10.00 GB (0401)
4.2
General instructions
Assembly and disassembly may be performed by qualified personnel only. Always wear
the appropriate safety clothing. Make sure that the personnel is properly instructed and
educated.
Insufficient or wrong assembly and disassembly can lead to the pump malfunction.
Johnson Pump is not liable for accidents and damage caused by non-compliance with the
guidelines.
Always work in a clean surrounding. Keep all highly sensitive parts such as seals,
bearings, etc. in their original packaging as long as possible.
Use a stainless steel work surface.
For maintenance and repair use only appropriate tools that are in good condition.
Check that the parts to be used have not been damaged during transport.
Never work on the pump in operation. In case of a disassembled pump, avoid any
contact with the rotors when turning the shaft manually.
Do not forget that the pump can be started even when the pump cover has been remo-
ved for e.g. cleaning. Never run the pump without pump cover.
After disassembly carefully clean the parts and check them for damage, especially the
mounting surfaces, and replace all damaged parts.
All parts fitted together at the disassembly must stay together when reinstalled,
especially the rotors, shafts, bearings and shims.
4.3
O-rings and lip seals
When working with lip seals or O-rings, take care not to damage them as they pass over
any sharp edges of splines, threads, etc. Be sure that the O-rings are not twisted in the
groove when installing.
All O-rings and sealing lips should be lightly lubricated with a suitable lubricant before
fitting, e.g. soap water.
For O-rings made of PTFE, it is advised to heat them up in hot water before placement.
A warmed up O-ring becomes more soft, thus easier to install.
4.4
Shutdown
Before starting the maintenance or inspection, follow the next steps to shut down the
pump.
1. Stop the pump. To prevent the motor from starting while you are working on the
pump follow the procedure below:
a) Turn off the pump at the electrical cabinet
b) Set the pump circuit breaker to off
c) Secure the circuit breaker from switching on with a lock. If not possible take the
fuses with you to the working place. Sign the electrical cabinet “out of work”
d) Remove, if necessary, the protection around the mechanical coupling only when
the pump has come to a complete standstill.
2. Let the pump cool down to the ambient temperature, if suitable for the liquid being
pumped.
3. Isolate and depressurise flushed product auxiliary services.
4. Close both suction and discharge valves.
5. Drain and purge the pump head and pipe work.
6. Clean the pump externally before disassembly.
