Vaisala K-PATENTS PR-23 Series, Instruction Manual, Page: 131 / 246

9 Sensor specifications 121
9.8 Teflon body refractometer PR-23-M/MS
Teflon body refractometer PR-23-M/MS is designed for use in chemically aggressive
solutions and ultra-pure fine chemical processes.
PR-23-M is an all-purpose model, PR-23-MS is designed especially for the semicon-
ductor industry. The sensor has a built-in flowcell designed to keep all metal and other
easily corroding parts from coming into contact with the process liquid. All the wetted
parts are made of non-metallic materials, either PTFE (Teflon
®
) or PVDF (Kynar
®
),
and thus the PR-23-M/MS sensor withstands corrosion very well.
Figure 9.27 The PR-23-M/MS sensor
Figure 9.27 shows the structure of the sensor. The flowcell (N) and the sapphire plate
(L) are fixed to the stainless steel sensor with four screws. The flowcell (N) is sealed
by a Kalrez O-ring (M). The flowcell prevents any leakage reaching the metal parts,
because there is a circular leakage chamber behind the O-ring (M). The chamber con-
nects to a checkport, which has a 1/8" female thread connection.