Bell & Gossett P81845B Series 3530 Centrifugal Pumps - Manual (Page 4)

3.2 Suction pipe must be at least as large as the suction
connection of the pump. Smaller size will degrade
performance.
3.3 If larger pipe is required, an eccentric pipe reducer
(with straight side up) must be installed at the pump.
3.4 Installation with pump below source of supply:
3.4.1 Install full flow isolation valve in piping for inspec-
tion and maintenance.
3.5 Installation with pump above source of supply:
3.5.1 Avoid air pockets. No part of piping should be
higher than pump suction connection. Slope pip-
ing upward from liquid source.
3.5.2 All joints must be airtight.
3.5.3 Foot valve to be used only if necessary for prim-
ing, or to hold prime on intermittent service.
3.5.4 Suction strainer open area must be at least triple
the pipe area.
3.6 Size of inlet from liquid source, and minimum submer-
gence over inlet, must be sufficient to prevent air
entering pump through vortexing. See Figs. 2-5.
3.7 User 3-4 wraps of Teflon tape to seal threaded
connections.
4. DISCHARGE PIPING
4.1 Arrangement must include a check valve located
between a gate valve and the pump. The gate valve is
for regulation of capacity, or for inspection of the pump
or check valve.
4.2 If an increaser is required, place between check valve
and pump.
4.3 Use 3-4 wraps of Teflon tape to seal threaded
connections.
5. ROTATION
5.1 Correct rotation is right-hand (clockwise when viewed
from the motor end). Switch power on and off quickly.
Observe shaft rotation. To change rotation:
5.1.1 Single-phase motor: Non-reversible.
5.1.2 Three-phase motor: Interchange any two power
supply leads.
6. OPERATION
6.1 Before starting, pump must be primed (free of air and
suction pipe full of liquid) and discharge valve partially
open.
6.2 Make complete check after unit is run under operating
conditions and temperature has stabilized. Check for
expansion of piping.
7. MAINTENANCE
7.1 Close-Coupled Unit. Ball bearings are located in and
art part of the motor. They are permanently lubricated.
No greasing required.
8. DISASSEMBLY
Complete disassembly of the unit will be described.
Proceed only as far as required to perform the mainte-
nance work needed.
8.1 Turn off power.
8.2 Drain system. Flush if necessary.
8.3 Remove motor hold-down bolts.
8.4 Disassembly of Liquid End:
8.4.1 Remove casing bolts (370).
8.4.2 Remove back pull-out assembly from casing
(100).
4
CAUTION: Do not use suction isolation valve to
throttle pump.
Failure to follow these instructions could result in serious
personal injury or death, and property damage.
CAUTION: Pumped liquid provides lubrication. If
pump is run dry, rotating parts will seize and mechani-
cal seal will be damaged. Do not operate at or near zero
flow. Energy imparted to the liquid is converted into heat.
Liquid may flash to vapor. Rotating parts require liquid to
prevent scoring or seizing.
Failure to follow these instructions could result in serious
personal injury or death, and property damage.
Figure 2 Figure 3
Figure 4 Figure 5