Introduction; Refractometer Models - Vaisala K-PATENTS PR-23 Series Instruction Manual

1 Introduction

1 Introduction
The PR-23 inline refractometer is an instrument for measuring liquid concentration
in the process line. The measurement is based on the refraction of light in the process
medium, an accurate and safe way of measuring liquid concentration.
The inline refractometer sensor (in Figure 1.1) measures the refractive index n
the temperature of the process medium. This information is sent via the intercon-
necting cable (B) to the Indicating transmitter (C). The Indicating transmitter DTR
calculates the concentration of the process liquid based on the refractive index and
temperature, taking pre-defined process conditions into account. The output of the
DTR is a 4 to 20 mA DC output signal proportional to process solution concentration.
Process data can also be downloaded to a computer via an Ethernet cable.
A: Sensors
1.1 PR-23 refractometer models
The basic system of one or two sensors connected to an Indicating transmitter (DTR)
is the same for all PR-23 inline refractometer models. However, there are different
sensor models, each model is adapted for different process requirements.
The models PR-23-AC and PR-23-AP meet the 3-A Sanitary Standard requirements.
With an ATEX approved PR-23-...-AX sensor or a FM approved PR-23-...-FM sensor
or a CSA approved PR-23-...-CS sensor a PR-23 process refractometer system can be
used in potentially explosive atmosphere. The ATEX approved Intrinsically safe re-
fractometer PR-23-...-IA can even be used in explosive atmosphere. The Safe-Drive™
system with a PR-23-SD sensor enables safe sensor insertion and removal also when
process line is in full operation.
B: Interconnecting cables
Figure 1.1 Refractometer equipment
and
D
POWER
PROCESS INSTRUMENTS PROCESS INSTRUMENTS
C: Indicating transmitter
1