General Product Overview; Measurement Principle - Hach 8362sc User Manual

General Information

2.3 General Product Overview

2.3.1 Measurement Principle

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DANGER
The 8362 sc High Purity Water pH or ORP sensor is not approved for hazardous
locations.
The 8362 sc High Purity Water pH/ORP panel is preplumbed and includes the 8362 sc
High Purity Water Sensor
mounting assembly. The 8362 sc High Purity Water pH/ORP Sensor contains two
electrodes; one for pH or ORP and the other for temperature.
The water runs through the 8362 sc High Purity Water Sensor then through a flow meter,
finally exiting the panel. The flow meter adjusts the sample stream from 0–300 mL/min
(0–300 cc/min.). The sensor then sends a mV signal and a temperature signal through
separate cords to a junction box which translates the analog pH/ORP and temperature
signal from the sensor into a digital signal to be read by the digital controller. Refer to
Specifications on page 5.
The 8362 sc High Purity Water panel is a manufactured panel to simplify and enhance the
connection between sensor and controller. It uses a self-pressurizing reference electrode
that introduces a constant flow of electrolyte into the sample stream. This constant flow of
electrolyte reduces the effects of electrolyte oscillations that cause reference junction
potential phase shifts that are found in other measuring systems. In addition, the
electrodes are housed in a special stainless steel housing and unique conductive flow
chamber to greatly reduce the effects of streaming currents that cause pH or ORP
measurements in high purity water to drift.
This 8362 sc High Purity Water pH/ORP system is specially designed for continuous
measurement of pure and ultra-pure water. It uses a reference electrode similar to the
measuring electrode to minimize the impedance of the measurement. The body is made
of 316 L stainless steel, which protects the measurements from electrostatic and magnetic
disturbances. The circulation chamber was designed without a retention zone to avoid
interference from CO dissolution, air bubble accumulation, or insoluble deposits
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accumulation (iron oxide, residues salted out by resins, etc.).
(Figure 1), digital electronics junction box, flow meter, and