1
Introduction
The Pyxis ST-525SS probe uses high temperature-tolerant and humidity-resistant optical filters. It can be
operated under a wide range of ambient conditions without the need of humidity and temperature regula-
tion. With this design the performance of the ST-525SS probe can be stable and consistent for an extended
period time.
The Pyxis ST-525SS probe measures the concentration of luorescein in water, commonly used as a fluo-
rescent tracer in water treatment applications. The 304-stainless steel body of the ST-525SS probe makes
it ideally suited for applications of monitoring boiler feedwater or boiler blowdown after being properly
cooled to near the ambient temperature. The 4-20mA current output from the probe can be connected to
any controller that accepts an isolated or non-isolated 4-20mA input. The ST-525SS probe is a smart de-
vice. In addition to measuring fluorescence, the ST-525SS probe has extra photo-electric components that
monitor the color and turbidity of the sample water. This extra feature allows automatic color and turbidity
compensation to eliminate interference commonly experienced in real-world applications.
The ST-525SS probe is easy to calibrate using the
uPyxis®
Mobile or Desktop App. Any standard containing
Fluorescein in the range of 10 to 60 ppb can be used for the calibration of the ST-525SSṪhe standard may
also be the water sample itself if the Fluorescein concentration of the sample is measured and validated
by a calibrated offline fluorometer. This allows the ST-525SS probe to be calibrated online without being
removed from the system. The
uPyxis®
App also provides diagnostic information about the ST-525SS probe
such as: probe fouling, color or turbidity over range, failure modes, etc. This diagnostic information can
also be available via Modbus RTU.
2
Specifications
Item
Specification
*
P/N
50666
Range
0-60 ppb
Resolution
0.2 ppb
Calibration
Two-point calibration against standard solution
Outputs
4-20mA Analog Output, RS-485 Digital Output with Modbus protocol
Installation
3/4” female NPT threaded ports on the probe itself
Cable Length
5 ft with IP67 connectors
Power Supply
22-26 VDC, 65 mA
Dimension
Length: 8.5 inch (220 mm), Head Cross-Section: 2.25 x 1.75 inch (57.2 x 44.5
mm), Body Diameter: 1.66 inch (42.2 mm)
Weight
2.5 lbs (1130 g)
Material
304 Stainless Steel
Operational
Temperature
40-104 °F (4-40 °C)
Storage
Temperature
20-140 °F (-7-60 °C)
Pressure
Up to 145 psi (1.0 MPa)
Enclosure Rating
IP67
Regulation
CE
*
With Pyxis’s continuous improvement policy, these specifications are subject to change without notice.
ST-525SS User Manual
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