Vogt NM Series, Service Manual, Page: 12 / 30

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Installation
If the pump sucks under load, the suction pipe must be stagnant and with a diameter generally larger than the pump mouth. The
diffuser cone can be eccentric or concentric. Install a gate valve for isolation during maintenance, see figure 11.
Figur e 11 Figur e 10
CHECK VALVE
Lc=7x(0 -0 )
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10x0
0
1
0
2
0
0
4x0
CHECK VALVE
Lc=7x(0 -0 )
1 2
10x0
0
1
0
2
0
Installation
The end of the suction pipe, which goes at the source of the fluid, should be submerged at least 4 times its diameter to avoid
the formation of vortices, which cause air to pass into the pump and cut off the liquid flow, Figure 10.
After the suction and discharge pipes have been installed, they should be cleaned of any debris before starting up the
equipment, in order to avoid damage to the pump and other equipment installed in the system.
It is advisable to use a suction strainer in the suction pipe, amply dimensioned to prevent the entry of dirt larger than the size
allowed by the pump. Avoid sharp bends and fittings that narrow or widen abruptly (cones, valves, etc.).
The discharge piping should generally be larger in diameter than the pump discharge flange. A gate valve should also be fitted
to regulate the flow rate and prevent possible motor overloads, as well as to isolate the pump during maintenance. To prevent
fluid backflow from the delivery line, it is recommended that a check valve be placed in the delivery line between the pump and
the control valve.
If the pump is in negative suction, the suction pipe should be absolutely stagnant and always rising towards the pump, with
diameter generally larger than the pump suction flange. The diffuser cone for the adaptation shall be eccentric with horizontal
top. Check that, at the normal duty point, the NPSH required by the pump is at least 0.5 m lower than the available NPSH of the
installation. To prevent the pump from overpriming at a standstill, a foot valve should be placed at the end of the suction pipe. It
is recommended that the length of the cone diffusers be at least 7 times the difference of the nominal diameters of the inlet and
outlet of the cone, see figure 10.