Nilfisk-Advance MC 6P Service Manual page 33

Function
D
By-Pass valve system_MC 6P
13
8
12
9
9
2
3
10 11 10
5
1
7
6
4
14
By-pass valve function in by-pass mode.
Motor is running, spray handle is CLOSED, water is NOT flowing to the HP nozzle.
Now the water flow in the bypass valve stop—no flow through the injector nozzle—so no pressure
drop.
Now pressure builds up (spray handle is closed) until the setting of the safety valve (14) which
opens shortly. When there is no pressure drop over the injector nozzle, the pressure in area (1, 2, 3,
4, 5, 6) will be the same. Because of a larger area on the lower side of piston (10) than on the upper
side, together with the area on the stem (close to the cone/seat (8), the lower piston (10) together
with the stem will move up.
When these two components moves up, the cone will lift from the seat (8), and water can now flow
through. Water is now flowing through a small valve in the by-pass channel (12) and back to the wa-
ter inlet side of the pump. The purpose of this small valve is two things—to help creating correct by-
pass pressure, and to make it possible to suck water with the pump.
SM_MC_6P Ver.2.0_2021
33