Suction Line; Discharge Line - Seko SPRING Manuel D'installation

2.3 Suction line (see installation recommendations table)
 Install pipe as short as possible (fig. 1) and avoid tortuous paths (fig. 2)
 Pipe should be sized considering that the ratio between the maximum instantaneous flow rate and the average
flow rate is 3,14.

Indicatively the installed pipe should have a diameter equal to 1.5 the diameters of the pump nozzles.
 For your guidance the recommended flow speed inside the pipes should be 0,5÷0,8 m/sec with liquids having
viscosity near water and specific gravity up 1200 Kg/m
 A permanent suction filter must be installed . The filter should have a filtering cartridge of 150 µm giving a pres-
sure drop less than 0.2 m.w.c. (calculated according to the a.m. coefficients). The filter should be easily acces-
sible and periodically checked and washed.
 In case of long lines and in order to avoid cavitation problems, install, near the pump, an expansion tank or a
damper (fig. 3).
 To prevent suction of impurities don't connect suction line to the bottom of the tank (fig. 4)
 Suction from a vacuum tank can be achieved by connecting pipes as per fig. 5. open check valve 2 and verify
the filling through the the window 3, close the check valve 2, start the pump; the non-return valve 4 prevents liq-
uid to flow-back when pump is stopped.
Q Portata
Q Portata media
A
Q Portatamassima
M
a Corsa di scarico
Corsa di aspirazio-
b
ne
t Tempo
2.4 Discharge line (see installation recommendations table, pag. 17)
 Verify that between suction and discharge there is a positive pressure of at least 50÷ 100 Kpa; if the plant con-
ditions don't permit a positive pressure difference, install a back pressure valve on pump discharge (fig. 6) or
lower suction tank (fig. 7) or raise discharge pipe (fig. 8)
 For safety reasons it is mandatory to install a pressure relief valve in order to prevent dangers as consequence
of unexpected overpressure; the pressure relief valve discharge should be visible and/or piped back to the tank
or to a drain.
We do not recommend to pipe the pressure relief valve discharge to the pump suction line (fig. 9).
 In case a back pressure valve is installed the pressure relief valve must be installed as shown in fig. 10.
 It is recommended the installation of pressure gauges having a range of 20% higher than the pressure relief
valve setting.
 To reduce flow pulsation, the installation of a pulsation damper near the discharge valve of the pump is highly
recommended.
The most used dampers are:
 dampers with direct contact between process liquid and gas/air cushion (air chamber); this type is of simple
concept but it needs frequent checks and restoring of the atmospheric air cushion.
SPR0136001
Q
a
b
Caudal Flow rate
Caudal promedio Medium Flow rate
Caudal máximo Maximum flow rate
Carrera de impul-
Discharge stroke
sión
Carrera de aspira-
Suction stroke
ción
Tiempo Time
3
.
Q = 3,14 x Q
M
Q
M
Q
A
Fig. D
Débit
Débit moyen
Débit maximale
Course de refoule-
ment
Course d'aspiration
Temps
Rev. 2.4 EN
A
t
Förderleistung
Duchschnittliche
Max. Durchflus-
smenge
Auslaßhub
Ansaughub
Zeit
5