4.
Any reducer should be of the eccentric type. If a reducer is used in the horizontal run of suction
piping, it must be used with flat part of reducer on the top to avoid air pockets.
5.
A horizontal portion of the suction line must have a gradual rise to the pump from the source of
the liquid being pumped. Any high point in the suction line will create an air pocket, and will pre-
vent proper pump operation and inhibit priming capability.
6.
An installation requiring long pipe lines handling hot or chilled liquids, requires provisions for re-
lieving the expansion and contraction of the pipe to eliminate any pipe stress from acting on the
pump casing.
7.
It is recommended to use long radius elbows and eccentric reducers whenever possible. These
types of fittings reduce friction loss. Tapered reducers should only be used in vertical suction pip-
ing.
8.
If a suction strainer is used, it should have mesh size equal to or less than the solid handling ca-
pability of the pump, and open mesh area equivalent to a minimum of eight times the area of the
suction pipe size.
9.
The size and length of the suction pipe, the number and type of pipe fittings, and the height of the
static suction lift will determine the total dynamic suction lift of each piping system. This system
characteristic should be calculated so that it does not exceed the design capacity of the pump
causing reduced flow and/or cavitation.
10. Before tightening the suction pipe connection flange, align it exactly with the pump suction flange.
Do not pull a pipe into place by tightening the flange bolts and/or couplings. All pipe lines near
the pump must be rigidly supported to avoid strain on the pump, which may cause excessive vi-
bration, decreased bearing life and/or increased shaft deflection and seal wear.
11. Leaks in the suction line can adversely affect both the pump's priming, and performance; espe-
cially when the pump is operating at high suction lift. To prevent leaks, make sure all piping con-
nections are tightly sealed. The piping gasket sealant used should be compatible with the liquid
being pumped.
12. If a single suction line is installed into a sump, it should be installed away from the sump wall at a
minimum distance equal to 1Y:z times the diameter of the suction line. If more than one suction
line is installed in the same sump, separate the suction lines from each other by a minimum dis-
tance equal to three times the diameter of the largest suction line.
13. If there is a discharge from an open pipe into the sump, the flow should be kept away from the
pump's suction pipe. This inflow usually carries air down into the sump with the liquid. Liquid with
entrained air will increase pumping time and reduce pump efficiency. If the discharge into the
sump is close to the suction pipe, install a baffle between the inflow and suction pipe at a dis-
tance of at least six times the diameter of suction pipe away from the suction pipe. The baffle will
allow the air to escape from liquid before it is drawn into the suction pipe.
14. Recommended is the use of bell type increasers at the bottom of the suction pipe to reduce inlet
velocity. If this can't be done, cut the bottom of the suction pipe at a 45° angle to avoid swirling of
liquid.
15. Refer to Hydraulic Institute Standards general guideline for sump design.
4.1.6.1 Valves
ITT does not recommend the use of a valve on the suction line EXCEPT:
a) In case where positive suction heads are present in the line EXCEPT:
b) Where it is possible for a positive head to develop due to flooding conditions.
c) Sometimes it is advisable to have valves on suction and discharge so that the pump may be isolated
during repair.
In any case, if suction valve is used, install with stems in horizontal position to avoid air pockets.
1.
If throttling valves are necessary in the discharge line, use a valve size equivalent to the largest
pipe size in the line to minimize friction loss. Never install a throttling valve in the suction line.
4.1 Pre-installation
Model Trash Hog II Installation, Operation, and Maintenance Manual
27
