Pyxis ST-730 Series and ST-73X-SS-T Inline Turbidity Sensors

The Pyxis ST-730 series and the ST-73X-SS-T family are inline turbidity sensors that share the same 90° surface scatter nephelometric measuring principle but differ in body material and mounting. The ST-730 series has a CPVC or 304 stainless steel body for standard piping pressures. The ST-73X-SS-T is made entirely of 316L stainless steel and is a removable, plug-in design for high-pressure critical cooling applications. In Turkey, Mikron Proses (Üsküdar, Istanbul) provides application consulting on range, body material and mounting selection.

Range selection · Body material · Mounting → Send us your requirement

For background on the measurement, see the guide on online turbidimeters. For ultra-low turbidity in drinking water, see the Pyxis LT-73X sensors.

ST-730 series: four ranges, CPVC or stainless steel body

ST-730 (0-100 NTU), ST-730B (0-1,000 NTU), ST-731 (0-10 NTU) and ST-735 (0-10,000 NTU) are four range options of the same platform, all with ±2% of reading accuracy. ST-730 and ST-731 use a white LED light source and are US-EPA compliant; ST-730B and ST-735 use a white LED below 100 NTU (US-EPA) and an infrared LED above 100 NTU (ISO compliant). The CPVC models are mounted to ¾ in FNPT with the ST-001 tee, work up to 6.9 bar (100 psi) and are rated IP66; they are 172.7 mm long, 36.6 mm in diameter and weigh 170 g. The ST-730SS offers the same 0-100 NTU range in a 304 stainless steel body. With its ¾ in FNPT connection it can be used on high-pressure lines up to 20 bar (290 psi), and it weighs 1,148 g.

ST-73X-SS-T series: removable stainless steel sensor

ST-730SS-T (0-100 NTU) and ST-731SS-T (0-10 NTU) are the 316L stainless steel versions of the ST-730 platform. They can be inserted into and removed from the new Pyxis ST-009 series stainless steel tees and multi-sensor flow manifolds. They work with an infrared LED and 90° surface scatter, are ISO-7027 compliant, and use optical filters tolerant of temperature and humidity. Together with the ST-009 tee they withstand up to 20 bar (290 psi); they are rated IP67, 182 mm long, 37 mm in diameter and 500 g. The manufacturer positions this series for high-pressure critical cooling applications.

Outputs, Bluetooth and calibration

All ST-730 and ST-73X-SS-T models draw 1 W from a 22-26 VDC supply and provide an isolated 4-20 mA analog output and an isolated RS-485 Modbus output at the same time. With an MA-WB (7-pin) or PowerPACK Bluetooth adapter, the uPyxis app gives wireless cleaning, live graph monitoring and calibration over Bluetooth 5.0. Calibration is a two-point procedure against formazin standard solutions. For the ST-73X-SS-T, a process sample verified with a calibrated offline turbidimeter can also be used, which allows the sensor to be calibrated in place without removing it from the system. The manufacturer recommends cleaning and calibrating at least once a month; in clean water applications this interval can be extended.

Ordering information

ST-730 (P/N 53201), ST-730B (P/N 53202), ST-731 (P/N 53505), ST-735 (P/N 53204) and ST-730SS (P/N 50626) are the SKUs of the ST-730 family. ST-730SS-T (P/N 56377) and ST-731SS-T (P/N 55995) are a separate product line and need an ST-009 tee, sold separately. Which body material (CPVC, 304 stainless steel or removable 316L), measuring range and pressure class suits your process is reviewed together with you. Tell us your requirement and we will select the right model and mounting combination.