Metex 8760CLP Total Free Chlorine & pH Analyzer - Manual (Page 46)

AQUAMETRIX INC.
1-800-742-1413 www.aquametrix.com
46
GLOSSARY
Electrode
Both a sensing and a reference electrode are needed for the analyzer to measure the process. Commonly these are combined
into one and referred to as a combination electrode. The temperature sensor may be built into the electrode as well.
EPROM
Erasable/Programmable Read Only Memory. The EPROM chip holds the program which determines the functioning of
8760CLP analyzer. Replacing the EPROM chip with a chip containing a new or an updated program changes the way the
analyzer functions. The EPROM chip is programmed by the manufacturer.
Free Available Chlorine
The hypochlorous acid form of chlorine; HOCl.
Hysteresis
The reading at which an alarm is turned on is not the same reading at which the alarm is turned off again. This phenomenon is
referred to as the hysteresis.
LED
Light Emitting Diode. LEDs are used as on/off indicators on the front panel of the 8760CLP.
Menu
The series of prompts which determine the layout of the program used by the analyzer.
Microprocessor
An integrated circuit (chip) which executes the program on the EPROM chip and controls all the input/output functions.
Nernst Equation
Equation which relates the voltage signal produced by the electrodes to the pH of the sample. The equation is temperature
dependent.
NC, Normally Closed
NO, Normally Open.
Normally Closed
Each of the alarm contacts can be wired and configured as normally open or normally closed. A circuit which is wired
normally closed will be closed, ie. the external device wired to it is turned on, when the analyzer is not powered.
Normally Open
A circuit which is wired normally open will be open, ie. the external device wired to it is turned off, when the analyzer is not
powered.
On/off Control
Control response in which the contact is either fully on or fully off.
ppm, Parts per Million.
1 ppm = 1 mg/L. Unit of concentration for chlorine measurement.
RAM
Random Access Memory. Memory in a RAM chip can be both written to and read from. The contents of RAM will disappear
as soon as the RAM chip loses power. The RAM chip has a battery backup device which preserves the contents of the RAM
chip for a considerable time even if the analyzer is turned off. All settings are stored in RAM.
TC, Temperature Compensator.
Temperature Compensation
Correction for the influence of temperature on the sensing electrode. The analyzer reads out concentration as if the process
were at 25 °C, regardless of actual solution temperature.
Total Free Available Chlorine
Sum of the hypochlorous acid (HOCl) and hypochlorite ion (OCl - ) forms of chlorine.