Vogt N Series, Руководство по обслуживанию, Страница: 16 / 31

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Installation
Figur e 12
The elbows and fittings installed in the pump suction must be selected and installed in such a way that the liquid enters the
impeller in a symmetrical and orderly manner, this is achieved by installing a section of pipe of the same diameter as the
pump suction and a length of 10 times that diameter, Figure 12.
The end of the suction pipe, which goes at the source of the fluid, must 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 13.
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 port. A gate valve should also be
fitted to regulate the flow rate and prevent possible overloading of the motor, 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 must be absolutely stagnant and always rising towards the pump, with
diameter generally larger than the suction port of the pump. The diffuser cone for the adaptation shall be eccentric with the
upper part horizontal. Check that, at the normal working 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 13.
CHECK VALVE
CHECK VALVE
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 14.
Installation
If a reduction is installed in the suction line, it should be eccentric and its straight part should be at the top, to facilitate the exit
of trapped air bubbles to the pump, see figure 12.
Figur e 1 3 Figur e 1 4