WARNING:
Assure that the system operating conditions are within the capabilities (e.g. – pressure, tem-
perature, power, etc.) of the pump. Exceeding any of the limits could result in failure of compo-
nents resulting in serious physical injury and damage to equipment.
5.5 Shutdown procedure
WARNING:
Do not operate pump below minimum rated flows or with suction and/or discharge valve closed
or with suction and/or discharge line blocked. These conditions may create an explosive haz-
ard due to vaporization of pumpage and can quickly lead to pump failure and physical injury.
During brief shutdowns (approximately four hours or less), it is usually sufficient to flush and drain the
standpipe, pump and control valve without displacing the stock in the entire discharge line. During ex-
tended shutdowns (over four hours), it is recommended to also flush and drain the discharge line.
Stop the pulp flow to the standpipe. After the pulp is pumped from the standpipe and the discharge pip-
ing has been cleared of stock, the Model 3500XD can be shut down.
During the shutdown sequence, the dilution system, air removal valve and vacuum pump should be in
the auto mode. After the Model 3500XD is shut down, the air removal valve and the vacuum pump
switch should be changed to the off mode.
The seal water to the mechanical seal and the vacuum pump can be shut off. If the seal water to this
mechanical seal is left on, the standpipe can gradually fill up with water.
5.6 Operation without a vacuum pump
The Model 3500XD can be supplied both with and without a vacuum pump. Services with design pulp
consistency of 10% or less can be supplied without a vacuum pump. When a vacuum pump is supplied
the flowing operating instructions can be utilized.
If, for some reason, maintenance is required on the vacuum pump and an interruption in production is
not wanted, it may be possible to change out the vacuum pump by the following procedure.
Raise the set value of the level controller 70 to 75% and open the dilution valves 75%. This should dilute
the stock to the point where operation without a vacuum pump can be achieved.
Reduce the vacuum in the air removal system, watching to make sure the level in the standpipe does not
increase. If the level increases excessively or does not stop, increase the amount of dilution until the
pump will operate without air removal system.
Stop the vacuum pump. If the standpipe level remains at its set valve, the vacuum pump can be removed
from the system and repaired or replaced.
5.7 Monitoring during operation
The pump operation is monitored in the control room with:
•
Standpipe level indication
•
Discharge control valve position
•
Pump speed, if variable speed drive
•
Upper dilution valve position
•
Lower dilution valve position
5.5 Shutdown procedure
3500XD Installation, Operation and Maintenance Instructions
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