Introduction; Principle Of Operation; 7320 Series Systems - ABB 7320 Series Instruction Manual

1 INTRODUCTION

1.1 Introduction
Warning. This instrument uses a high intensity
light source which emits ultraviolet (UV) radiation and
must NOT be viewed with the naked eye. Under normal
operating conditions it is not possible to see the light
source, but if the sensor is dismantled with the power
applied, it may be possible to expose the eyes to the
strobe flash.
Many dissolved organic compounds (DOC) commonly found
in potable water strongly absorbs ultraviolet radiation. These
include Humic Acid, which gives water a characteristic yellow
and dissolved organics with results in the formation of
Trihalomethanes (THMs).
The monitor is used as a surrogate colour monitor, monitor and
control coagulation, and to monitor THM precursors in potable
water treatment plants.

1.2 Principle of Operation

The monitor employs a broad-spectrum xenon strobe lamp to
generate pulses of light which pass through the sample water
in the flowcell to a filtering and detection system. The received
light pulses are analysed at two wavelengths: the
measurement wavelength of 254 nm and the reference
wavelength of 400 nm, at which the sample constituents of
interest do not absorb. This dual light path system provides
information which allows the measured value to be corrected
for any turbidity due to suspended matter in the sample. The
monitor is calibrated with a pure solution of a suitable organic
compound of known carbon content.
An automatic, microprocessor-controlled, dual-wiper system
cleans the flowcell optical windows periodically to ensure that
the cell remains functional. Samples containing large solids
and/or very high concentrations of solids must be pre-filtered.
2
1.3 7320 Series Systems – Fig. 1.1
• The 7320/1000 low range analyzer primarily for use in
potable water applications, such as monitoring the
effectiveness of the coagulation control, THM precursor
detection and final treated water quality.
Range: 0 to 20 mgl -1 C maximum.
• The 7320/2000 high range analyzer is used for intake
protection applications on potable water applications to
detect the rise in DOC from algal bloom toxins and
industrial discharges.
Range: 0 to 100 mgl -1
• The 7320/3000 high range coagulation analyzer is
designed to monitor the raw water in potable water
treatment plants to predict the coagulant dose.
Range: 0 to 100 mgl -1
7320 100
Low Range System
7320 200
High Range System
7320 300
Coagulation Dose System
Fig. 1.1 System Arrangements
C maximum.
C maximum.
7320 000
7320 000
7320 000