Functional Principle - Grundfos Vaccuperm VGA-113 Montage- Und Betriebsanleitung

4.2 Functional principle

4.2.1 Dosing regulator
The dosing regulator regulates the chlorine gas flow with a valve.
The flow is read at the top of the ball in the measuring glass.
4.2.2 Vacuum chlorine gas dosing system
Fig. 13 Principle of a vacuum chlorine gas dosing system
Pos. Description
A Chlorine cylinder
B Vacuum regulator
C Dosing regulator
D Injector
E Adsorption filter (option)
F Safety valve (option)
G Change-over device (option)
H Water apparatus (option)
I Chlorine gas pressure line
J Chlorine gas vacuum line
Functioning of a vacuum chlorine gas dosing system
Handling, transport and storage of chlorine for the disinfection of
drinking and pool water are a challenge for plant engineers.
This is the reason why the vacuum principle has been used in
dosing systems for a long time. The pressure of the chlorine gas
is reduced to a vacuum.
This method prevents escape of chlorine gas. In the event of a
pipe burst no chlorine gas can escape, only ambient air is
drawn in.
Vacuum chlorine gas dosing systems are composed of three
principal components.
14
Vacuum regulator (B)
The vacuum regulator is a pressure reducing valve, which
reduces the overpressure from the chlorine tank side to the
negative pressure on the vacuum side. The valve opens, when a
sufficient vacuum has built up on the outlet side.
Vacuum regulators with pressure gauge and liquid trap are
available for more safety.
Dosing regulator (C)
The chlorine gas flow is adjusted with the dosing regulator.
This can be effected manually or automatically via motor control.
Injector (D)
Injectors have the task to bring chlorine gas into the water flow.
They operate according to the principle of water jet pumps. The
injector body comprises a nozzle with a successional diffuser.
Between the nozzle and the diffuser there is a narrow annular
gap, where chlorine gas is sucked out of the dosing line through
the injector head. A diaphragm non-return valve at the end of the
vacuum line prevents the ingress of water into the vacuum line.
Differential pressure regulator (I)
Regulates the difference of the pressures before and after the
rate valve to a constant value. Adjusted dosing flow stays
constant even when the injector vacuum varies.