Goulds Pumps 3500XD - IOM - Manual (Page 26)

LEVEL CONTROL
(Refer to Figure 16A and 16B)
For Order Specific Description - Refer to the IOM Appendix
A level must be maintained in the suction standpipe for
proper pump operation and air removal. A level transmitter
(LT) must be installed to measure standpipe level and
provide a signal to a level controller in the control room.
The level measurement range is 0 - 100%. This span must
be oriented properly on the standpipe and the length of the
span will be dependent on the application and the type of
level transmitter used. Refer to the IOM Appendix for the
order specific information on the level span.
Standpipe level is set on the level controller in the control
room. Output from the controller is the input to the level
control valve (LCV) on the discharge of the Model
3500XD pump.
High and low alarms in the control room should be set at
85% and 10% respectively. Neither alarm should be
interlocked to shut down the Model 3500XD. The Model
3500XD will not start if the standpipe level is less than
10%.
Additional recommendations for level control valve
operations are:
· Low limit stop of 10% open
· In the event of the valve failing closed, a time delay
of one minute in the fully closed position shall
require the 3500XD motor to stop.
The exact operating level for the standpipe must be set for
each specific application to obtain optimum air removal
and pump performance. With stock temperatures up to
170° F, a level of 3’ to 5’ above the pump centerline is
typical. Above 170° F, the level must be increased to
account for the increased vapor pressure of the stock. Refer
to the IOM Appendix for the order specific information on
the standpipe operating level, high and low level alarms.
If the unit is equipped with a variable speed drive, output
from the level controller would control the pump speed
rather than the LCV position. Refer to the IOM Appendix
for the order specific information on the control scheme for
variable speed drive systems.
For Model 3500XD units operating at 10% consistency or
less, the level control system is the same as the above .
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3500XD IOM 8/07