ALIGNMENT
CHECK ALIGNMENT AFTER MOUNTING
For detailed coupling alignment procedures see coupling
manufacturers’ recommendations.
The pump, drive, and motor were properly aligned at the
time they were assembled. During shipping and mounting
the alignment is often disturbed.
BE SURE TO RECHECK
ALIGNMENT AFTER THE PUMP UNIT IS INSTALLED!
1.
Check pump ports to be sure they are square and in the
proper position; shim or move the pump as required. Do
not force piping to line up with the ports.
2.
If the pump is driven by a flexible coupling(s) either directly
connected to the motor or through a reducer, remove any
coupling guards or covers and check alignment of the
coupling halves. At a minimum, a straightedge (such as a
piece of key stock) across the coupling must rest evenly
on both rims at the top, bottom, and sides.
See
Figure A10-A
.
3.
If the pump is driven by V-belts, check the alignment by
using a long straightedge or tightly drawn string across the
face of the sheaves. See
Figure A10-B
.
4.
Make a final check on alignment after piping is hooked up.
Refer to item 13 in
Piping
section.
Figure A11
and
Figure A12
show typical direct drive and
gear reducer drive units.
5.
For high temperature applications (those above 300°F)
allow the pump to reach operating temperature, then
recheck alignment.
FIGURE A11: DIRECT DRIVE
FIGURE A12: REDUCER DRIVE
PIPING
The cause of many pumping problems can be traced to suction
piping. It should always be as large and short as practical. For
help in selecting the proper size suction and discharge piping,
refer to
Viking General Catalog Section 510
.
Before starting the layout and installation of your piping
system, consider the following points:
1.
Never use piping smaller than the pump port connections.
2.
Be sure the inside of the pipe is clean before hooking it to
the pump.
3. FOOT VALVE
- When pumping a light liquid with a suction
lift, a foot valve at the end of the suction piping or a check
valve in the first horizontal run will hold the liquid in the
line and make it easier for the pump to prime. Be sure the
foot or check valve is big enough so that it doesn’t cause
excessive line loss.
4.
When approaching an obstacle in the suction or discharge
line, go around the obstacle instead of over it. Going over
it creates an air pocket. See
Figure A13
.
5.
Where practical, slope the piping so no air or liquid
pockets will be formed. Air pockets in the suction line
make it hard for the pump to prime.
6.
For a suction line with a long horizontal run, keep the
horizontal portion below the liquid level if possible. This
keeps the pipe full of liquid and reduces the amount of air
the pump must evacuate at startup. This is most helpful
when there is no foot valve. See
Figure A14
.
7.
When piping a hot or cold system (liquid being handled is at
a temperature different from the air surrounding the pump),
be sure allowance is made for expansion and contraction of
the piping. Loops, expansion joints, or unsecured (this does
not mean unsupported) runs should be used so the pump
casing is not distorted.
8. STRAINER
- It is always good practice to consider a
strainer on the suction side of a positive displacement
pump. The strainer will keep foreign objects from going
into the pump. Without a strainer objects can lock the
pump, and damage the internals and drive. The strainer
basket mesh or perforation size should be big enough
so that it does not cause excessive pressure drop, but it
should be fine enough to protect the pump. When in doubt
as to the proper size, check with the manufacturer, giving
pipe size, flow rate, and viscosity involved. Provision
should be made for cleaning the strainer. If the pump
operates continuously, a bypass should be built around
the strainer, or two strainers should be put in parallel with
proper valving so they can be isolated for cleaning. Use of
a strainer is particularly important at start up to help clean
the system of weld beads, pipe scale, and other foreign
objects. For additional information, refer to
TSM 640
.
9.
If the pump is not equipped with a relief valve,
consideration should be given to mounting one in the
discharge line. Refer to discussion on pressure protection
under item 5 in
General Installation Notes
section.
10.
The pump should not be used to support the piping.
The weight of the piping should be carried by hangers,
supports, stands, etc.
11.
When fastening the piping to the pump it should not be
necessary to impose any strain on the pump casing.
“Springing” or “drawing” the piping up to the pump will
TSM 1741 | Issue B | Page 14 of 20
© 2019 Viking Pump, Inc. • Cedar Falls, IA
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