ST-730 Series are designed for monitoring the middle range turbidity in various applications. It is more robust and tolerant to fouling, particular matters, and air bubbles comparing to other online turbidity meters designed for relatively clean water applications.

It also offers desired resolution and accuracy comparing to high turbidity or commonly referred to as suspended solid meters (4000 to 9999 NTU).

ST-730 series turbidity probe measures two optical densities and two scattering intensities at two wavelengths. This helps measure a large turbidity range and yet maintain a fine resolution. This design also helps the probe run self-diagnoses.

Typical Applications

  • Industrial water treatment process control, including raw water, cooling water, and wastewater.
  • Surface water monitoring.
  • Other chemical processes with middle range of turbidity.


  • Dual-wavelength: white LED and IR LED 90° scattering to achieve more reliable and accurate reading in a complex flow system.
  • A small footprint compact design, similar to an industrial pH probe.
  • Isolated 4-20mA output. No need for additional transmitter for easy connection to PLC and DCS.
  • Isolated RS-485 output embedded for easy trouble shooting and calibration.


Range0~100 NTU0-10 NTU0~500 NTU0~4,000 NTU
Resolution0.1 NTU0.05 NTU1 NTU10 NTU
Accuracy±2% of reading or 1 NTU whichever is greater
MethodNephelometric, with light sources of White LED and IR LED (860nm)
Power Supply22-26V DC, Power Consumption ~1W
OutputsIsolated 4-20mA Analog Output
Isolated RS-485 Digital Output, Supporting MODBUS protocol
DimensionLength 6.8 inch, body diameter 1.44 inch
Weight0.37 pounds
InstallationCustom tee with 3/4” NPT ports
PressureUp to 100 psi
TemperatureOperation 40-120 °F, Storage 20~140 °F
Cable Length5 feet, terminated with IP67 connectors.
30 feet, 60 feet extension cables available
CalibrationTwo point calibration against standard solutions
RegulationCE marked
You've just added this product to the cart: