Vaisala K-PATENTS PR-23 Series, Instruction Manual, Page: 139 / 246

9 Sensor specifications 129
9.9 Saunders body refractometer PR-23-W
Saunders body refractometer PR-23-W is a heavy-duty instrument designed for chem-
ically aggressive liquids and ultra-pure fine chemicals in
large-scale production and
in large pipelines . The materials and design of the sensor are similar to the Teflon
body refractometer PR-23-M, but the Saunders body makes it possible to fit this re-
fractometer into 50, 80 or 100 mm (2", 3" or 4") pipelines.
The Saunders body material is graphite cast iron lined with 3 mm PFA (Fluorinated
ethylene propylene) or ETFE (Ethylene tetrafluoroethylene) fluoroplastic. The cast
iron provides a solid mechanical base and the PFA/ETFE lining ensures the chemical
resistance.
The sensor itself is built just like the PR-23-M sensor (see Section 9.8) and it is fixed to
the Saunders body in the same way, with a sapphire plate and a Kalrez O-ring to keep
all the metallic parts away from the process liquid.
PTFE wetted parts
Sapphire plate
O-ring (Kalrez)
Prism
Flow cell adapter
(AISI 316L)
Graphite cast iron
Saunders valve body flow cell
F
L
O
W
PR-23-W Sensor
PFA/ETFE
Figure 9.29 PR-23-W Saunders body sensor