Pyxis Dissolved Oxygen Sensors

The water treatment process comprises several steps and includes the measurement of many parameters present in water. One of them is dissolved oxygen which can be measured with the help of dissolved oxygen sensors. Dissolved oxygen (DO) is expressed in mg/L of water. This is a measurement of the percent saturation or concentration of oxygen in water that is available to the aquatic life inside it. Walchem offers premium quality optical luminescent dissolved oxygen measurement sensors in various configurations. We offer the Pyxis ST-772, ST-773, and Pyxis ST-774 ultra-low dissolved oxygen sensors.

Pyxis dissolved oxygen meters are designed on the principle of fluorescence quenching to measure the level of DO in water. The ST-773 Pyxis sensor is CPVC, while the ST-772 sensor is 304 stainless steel. ST-774 is a smart sensor that measures extremely low levels of residual DO. They all measure the oxygen partial pressure that is at equilibrium with the dissolved oxygen in water and based on Henry’s law and use advanced technology for fluorescence quenching to offer the most stable and accurate measurement of residual DO.

Types of Dissolved Oxygen Sensors We Offer

Pyxis Lab® ST-772 Dissolved Oxygen (DO) Sensor: The ST-772 Sensor is a type of dissolved oxygen analyzer that follows the principle of fluorescence quenching to determine the dissolved oxygen content in water. This dissolved oxygen sensor integrates both pressure and temperature sensors, which performs pressure and temperature compensation while measuring the dissolved oxygen based on ambient conditions of the application. It offers both 4-20mA and RS-485 Modbus outputs and is Bluetooth enabled when used in conjunction with the MA-CR Bluetooth Adapter. ST-772T model is designed to be installed inline and includes the ST-001 tee, while the ST-772 model is for submersion installations.

Pyxis ST772 Sensors

Key Benefits:

    • 0.004-20 mg/l measurement range
    • Simple DO membrane cartridge replacement every 2 years
    • Extremely scratch-resistant membrane
    • Accurate and stable measurement – no calibration for up to 2 years

Typical Applications:

  • Activated Sludge / Aerated Basin
  • Wastewater & Sewage Processing
  • Chemical & Process Water Applications
  • Domestic Water Applications
  • Filtration Applications
  • Aquaculture
  • Agriculture

Pyxis Lab® ST-773 Dissolved Oxygen Sensor: The ST-773 Sensor utilizes advanced fluorescent detection technology for dissolved oxygen measurement. It uses blue/red light detection technology with detection and reference light sources, with a wide detection range, as well as low detection limit. It has a flat front-end design because of which it is utilized in submersed fixed/floating applications or with the Pyxis submersion assembly and inline thread/tee accessory options. It comes with a 10m bulkhead cable as well as a 1.5m flying lead cable each with 7-Pin quick adapters. The sensor output offers both 4-20mA and RS-485 Modbus communication which is Bluetooth® enabled when used with the MA-WB adapter.

ST-773 Dissolved Oxygen Sensor

Key Benefits:

  • Inexpensive Luminescent Dissolved Oxygen sensor
  • 004–20mg/L Measurement Range – Stable Measurement with Ultra-Low Drift
  • Simple DO Cartridge Replacement
  • Dual Outputs both 4-20mA Isolated Signal & RS-485 Modbus
  • CPVC Body – Lightweight & Corrosion Resistant
  • Submersible or Inline Installations available using our Submersion or Inline Adapters

Typical Applications:

  • Activated Sludge /Aeration Tanks / Nutrient Removal / Wastewater
  • Chemical / Process Water / Domestic & Drinking Water
  • Filtration / Aquaculture / Agriculture

Pyxis Lab® ST-774 dissolved oxygen sensor: The ST-774 sensor is developed after years of extensive research and development at Pyxis Lab and incorporates a fully optical platform measuring ultra-low residuals of dissolved oxygen via Blue and Red Light sources. It is a fully integrated state of the art smart dissolved oxygen sensor that comes calibrated from the Pyxis factory enabling rapid deployment and simple maintenance and calibration for years of service. Designed specifically for cooled sample applications measuring ultra-low concentrations (0.4 to 2000 PPB) of dissolved oxygen the ST-774 is un-matched in the industry and is ideal for water and process applications requiring the utmost accuracy and range of detection.

Pyxis ST-774 Dissolved Oxygen Sensor

Key Benefits:

  • 0.4-2,000μg/L measurement range
  • Built-in temperature and pressure sensors
  • Accurate and stable measurement with ultra-low drift
  • Built-in transmitter without the need of using a preamplifier or meter head

Typical Applications:

  • HP Boiler Feedwater / Deaerator Storage
  • Power Facilities
  • Ultra-Pure Water
  • Closed Loops
  • Condensate Return
  • Beverage Production / Post Fermentation
  • Semiconductor Rinse Water

Benefits of Pyxis Dissolved Oxygen Analyzer

Here are some common benefits of our dissolved oxygen monitors.

  • Our sensors have a wide measurement range from 0.004 to 20 mg/l.
  • The ST-774 offers a measurement range of 0.4-2,000μg/L.
  • They offer accurate stable measurement with Ultra-Low Drift and require no calibration for at least two years.
  • They have a simple DO membrane cartridge replacement every 2 years.
  • These dissolved oxygen sensors come with built-in temperature and pressure sensors with automatic compression.
  • ST-773 is a cost effective option.
  • The membrane is scratch resistant, and the CPVC body makes the ST-773 lightweight and corrosion resistant.
  • We offer submersion and inline installation versions.

Applications of our Dissolved Oxygen Monitors

These are some common applications of our dissolved oxygen sensors.

  • Aquaculture and fish farming
  • Pharmaceutical and biotech manufacturing
  • Environmental monitoring
  • Activated sludge/aeration tanks/nutrient removal/wastewater
  • Chemical/ process water/domestic water treatment
  • Filtration process
  • Agriculture

If you require dissolved oxygen sensors as part of your system, we can offer you some of the best options in the form of Pyxis dissolved oxygen measurement sensors. At Walchem, we offer the best products with advanced sensing technologies for the water treatment market segment. With our Pyxis sensors, you can be sure about the accuracy and quality. If you have any questions regarding our dissolved oxygen sensors, wish to share your requirements, or discuss custom options, feel free to reach us at 508-429-1110. You can email us at