ST-500W Inline PTSA Sensor for Industry Standard Tee Assemblies

The ST-500 Fit for Existing Industry Known Tee Assemblies!

Measures for PTSA at an expanded range (0–300ppb), while simultaneously compensating for Color & Turbidity Interference, to provide a more accurate dosage reading. This variant fits perfectly into WALCHEM® and other industry-known tee assemblies! Use the MA-WB Bluetooth® Adapter to enable wireless monitoring, calibration & cleanliness diagnostics via the uPyxis® app!

CE Mark  



The ST-500W is a stainless steel inline PTSA Pyxis smart sensor uniquely designed to be directly inserted into the WALCHEM® and alternative fluorometer tee assemblies. Since the alternative fluorometers commonly used in the water treatment industry have very similar dimensions as the WALCHEM® tee design, the ST-500W design allows drop-in installation into both designs of inline tee assemblies without the need for plumbing modifications of equipment already in use.

The ST-500W is identical in internal design and function as the world-class ST-500 Series inline PTSA sensor platform offering the industry a proprietary design for the direct measurement of PTSA (Pyrenetetrasulfonic Acid, CAS# 59572-10-0) utilizing LED UV light sources (365nm ex/ 410nm em) and is specifically designed for use in industrial cooling water and process water treatment applications.

The ST-500W offers Pyxis proprietary algorithms to determine the concentrations of PTSA while measuring sample turbidity and color in highly contaminated waters (ie. <150 NTU and 10 ppm Fe) for internal compensation. The ST-500W offers a combination of 4-20mA as well as RS-485 Modbus output signals in 8-Pin cable format and is Bluetooth Enabled for wireless cleanliness diagnostics and calibration when used with MA-CR or PowerPACK Series Bluetooth Adapters and the uPyxis APP for Mobile or Desktop devices. The ST-500W comes equipped with 1.5m (4.9ft) bulk-head cable with quick adapter as well as 1.5m (4.9ft) flying lead cable with quick adapter, enabling rapid wiring to any microprocessor controller, PLC or DCS system.


Item ST-500W Inline PTSA Sensor
Part Number 58802
PTSA Output Scale 0-200ppb
PTSA Max Range via uPyxis® 0-300ppb
PTSA Precision/Accuracy ±1ppb
Excitation/Emission LED 365/410nm
Power Supply 22-26VDC, Power Consumption – 1W
Outputs Isolated 4-20mA Analog & Isolated RS-485 Digital – 7-Pin
Installation ST-001 Inline Tee (PROVIDED), 3/4inch FNPT
Weight 500g (1.1lbs)
Operation Pressure 100psi (6.9Bar)
Operation Temperature 4-49 °C (40-120 °F)
Storage Temperature -20-60 °C (-4–140 °F)
Material 304 Stainless Steel
Rating IP67, Dustproof & Waterproof
Regulation CE + RoHS
Dimensions 6.8in (172.7mm) L x 1.44in (36.6mm) D
Cable Length 5ft, Terminated with IP67 Adapter + 1.5ft Flying Lead

Support Documents

ST-500W User Manual V1.1

ST-500W Data Sheet



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