5
Introduction
General Information
Instrument Description and Capability
The FX-1000p Amperometric Chlorine Residual Analyzer amperometrically measures the free or total
residual chlorine in treated drinking water, process water, or wastewater using integral gold and copper
bare electrodes that are not covered by a membrane.
Amperometric measurement means that the chlorine residual reading is determined by measuring
the electronic amperage of the measuring cell. The amperage level is directly proportional to the
level of free chlorine available as hypochlorous acid in the sample stream. In the case of reading total
chlorine, the unit is actually reading converted free iodine from the potassium iodide that is added to
the cell for total chlorine readings.
The required continuous sample flow is brought to the analyzer from an existing pressurized line or
can be pumped from a well or reservoir. The sample flows by gravity through the flow/measuring cell
and discharges to waste after measurement.
A peristaltic pump continuously injects a precise amount of 5% food grade distilled white vinegar into
the sample to lower the pH in the measuring cell to 4-5 pH.
The system provides a 4-20mA analog output that is scaled to the factory set measuring range. This
output can be used to drive a residual chlorine control system using compound-loop or set point
controllers; or input to a chart recorder, telephone dialer, data logger, or SCADA system.
These important factors enable the FX-1000p to provide drift-free measurements:
1. Buffer solution feed rate is constant.
2. Flow rate to sample flow cell is kept constant.
3. Large surface area made with pure grades of gold and copper are used to measure the residual
chlorine.
4. The sample flow cell has a reliable cleaning method to keep the electrodes free of dirt, ensuring
measurement accuracy. The distilled white vinegar buffer solution, mixing balls, and process
chlorine act together to keep the flow cell clean.
