16
OPERATING DESCRIPTION
CHLORINE MEASUREMENT
Referring to the drawing on page 10 and the Fluidic Diagram
on page 17, the Sample Line is connected to the instrument at
the Sample Port (#17); an internal Regulator (#15) reduces
the inlet pressure from a maximum of 4 bar (57.2 psi) down to
1 bar (14.3 psi); from the Regulator a nylon tube is connected
to the input of the Electrovalve (#21). The output of the valve
goes to the Drain Port (#11) and then to the Measuring Cell
(#7). An optional Filter can be installed to the sample port if
the stream is excessively turbid.
The sample coming from the line normally flows through the
Measuring Cell (#7). It goes out from the Measuring Cell
through the Drain Tube (#8) and the Output Port (#9).
The Measuring Cell is accessible from the port placed on the
top (#6) for speedy cleaning and maintenance.
During the 100 seconds preceding the sampling, the ana-
lyzer solenoid input valve is open to allow sample flow to flush
the colorimeter cell. Every 3 to 90 minutes (user selectable),
the electrovalve closes stopping the sample flow and leaving
the sample cell full of fresh sample. Cell volume is controlled
by an overflow gateway.
As the sample inlet electrovalve closes, a series of measure-
ments (with LED on and off) of the unreacted sample is taken
to determine an average blank level prior to reagent addition.
The measurement of sample blank signal permits compensa-
tion for any turbidity or natural color, and provides the zero
reference point for the measurement.
The two channel Peristaltic Pump (#5) starts rotating causing
a precise quantity of buffer and indicator (#13 and #16) to
enter the colorimeter sample cell. Here a magnetically coupled
stirrer mixes the reagents with the sample.
After a delay for the color development, a series of measure-
ments (with LED on and off) are taken (sample level) to deter-
mine an average chlorine concentration measurement. The
reacted sample signal is then measured and displayed.
This sequence is repeated every 3 to 90 minutes (user-select-
able).