6
5. PIPING
The pump suction and discharge connections are not
intended to indicate the required suction and discharge
pipe sizes. The pipe diameter must be selected according
to the requirements of the pumping system and
recommended friction losses for the liquid being pumped.
Usually, it is advisable to increase the size of both the
suction and discharge pipes at the pump nozzles to have
minimum acceptable friction loss, suction pipe should
never be smaller in diameter than the pump suction
nozzle. When suction pipe is of larger diameter than the
pump suction nozzle, an eccentric reducer is required to
eliminate possible air or vapor pockets at the pump suction
inlet.
Both suction and discharge pipes must be supported
independently near the pump, so that when piping is
connected to the pump, no strain will be transmitted to the
pump. Piping should be arranged with as few bends as
possible, and, preferably, with long radius elbow whenever
possible.
SUCTION PIPING
A horizontal suction line must have a gradual rise to the
pump. Any high point in the suction pipe can become fi lled
with air and prevent proper operation of the pump and may
cause loss of prime. The pipe and fi ttings must be free of
all air leaks.
Any valves or fi ttings should located at a distance equal
to 5 to 10 times the diameter of the suction pipe from the
pump suction nozzle. If an elbow must be installed at the
pump suction, it should be installed in a vertical position
to reduce unequal fl ow into the pump, which may cause
cavitation in the pump.
NOTE:
A gate valve in the suction piping should not be
used as a throttling device, as this may cause the liquid to
overheat during operation.
FOOT VALVE
When it is advisable to install a foot valve to facilitate
priming, a spring loaded type check valve must be installed
next to the pump in the discharge line to prevent pump
rupture from water hammer shock. The foot valve should
have a clear passage for water not less than the same
area as that of the suction pipe. Care must be taken to
prevent foreign substances from being drawn into the
pump or chocking the foot valve. For this purpose an
eff ective strainer should be provided. When there is any
refuse such as sticks, twigs, leaves, etc., in the water, a
large outside screen should be placed around the suction
inlet to prevent chocking of the strainer. This screen should
have suffi cient openings so that the fl ow velocity does not
exceed two feet per second or a free area of four to fi ve
times the suction pipe area.
6. WIRING
For electric motor drives, connect power supply to conform
with national and local codes. Line voltage and wire capacity
must match the ratings stamped on the motor nameplate.
7. ROTATION
Before starting the pump, check the required direction
of rotation of the pump. The proper direction is indicated
by a direction arrow on the pump casing. Separate the
coupling halves, then start motor to see that it rotates in
the direction required by the pump. If it does not, reverse
any two main leads of the 3-phase wiring to the motor.
The coupling halves can be reconnected and the pump
primed for starting.
Figure 4
Summary of Contents for DEMING 4060 Series
Page 18: ...Notes ...
