The chlorine gas flow is rarely controlled by hand
in state-of-the-art chlorination installations according
to DIN 19606.
In the majority of cases, the concentration of free
chlorine in the water is monitored by an electronic
controller which sets the required chlorine gas quantity
by means of an electrically operated valve.
The control valve C7700 has been developed for this
purpose. It is a plastic valve for chlorination installations
based on the vacuum principle and therefore must not
be used with excess pressure.
2. Functional description
A servomotor with 90° bevel actuates the adjusting
eccentric (1). It converts the rotary motion into the
stroke movement of the valve spindle (2). Contact between
the valve spindle and eccentric is ensured by a spring
The actual control element is located at the lower
end of the valve spindle. Up to 2500 g Cl2/h, the control
element is designed as an air jet in the form of a helically
slotted cylindrical shaft (4); for larger
quantities, it takes the form of a control cone (5).
Both control elements are shaped so that the crosssectional
flow area changes in proportion to the
position of the servomotor. The valve has a linear characteristic.
For manual chlorination, the valve spindle can be lifted
completely upwards by pulling the hand knob
(6) and locked in position by means of the slide (7).
The chlorine gas flow is then adjusted at the needle
valve of the flow meter. The housing of the control
valve consists of two chambers, the valve chamber and
the eccentric chamber. The chambers are separated from
one another by a seal to prevent contact between the
mechanical drive and the chlorine gas.