Diaphragm liquid pump NF 300
Assembly and function
KNF Flodos BA_NF300_EN_08_068697.docx
Translated from the Original Operating and Installation Instructions
10
5. Assembly and function
Assembly
1
Outlet
2
Inlet
3
Connecting plate
4
Motor
5
Leads
6
Head plate
7
Intermediate plate
3
4
5
2
1
6
7
Fig. 1: Diaphragm liquid pump NF 300
1
Exhaust valve
2
Inlet valve
3
Working chamber
4
Diaphragm
5
Eccentric
6
Connecting rod
7
Pump drive
Fig. 2: Operating principle
Diaphragm liquid pumps are based on reciprocating displacement
pump technology. An elastic diaphragm (
4
) is moved up and down
by the eccentric (
5
) and the connecting rod (
6
). During the down
stroke, the diaphragm sucks in the medium through the inlet valve
(
2
). During the up stroke, it forces medium out of the pump head
through the exhaust valve (
1
). The diaphragm hermetically seals
off the working chamber (
3
) from the pump drive (
7
).
NF 300 version (specified flow rate)
This pump type is the simplest version of the listed products and
pumps media at the specified flow rate.
NF 300 .27 version (specified flow rate with
overpressure limiting)
If the diaphragm liquid pump is operating against a closed system,
the delivery pressure quickly exceeds the maximum permissible
values. To prevent this happening, an overpressure relief is inte-
grated in the top part of the pump head. If the pressure exceeds
the variable limit range (min. 1.5 to max. 6.5 bar
g
), the valve opens
and the liquid circulates from the pressure side to the suction side
via an internal bypass system. This prevents any further rise in
pressure.
