Chemtrol Australia Product - ST-772 Series Luminescent Dissolved Oxygen Sensors

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ST-772 Series Luminescent Dissolved Oxygen Sensors

Product Details
Specifications
Wastewater & Aeration
Installation
Video

ST-772 Series Luminescent Dissolved Oxygen Sensors

The Pyxis ST-772 sensors measure dissolved oxygen optically. Light from inside the sensor makes the membrane cap glow, and oxygen in the water dims that glow; the sensor turns the change into a DO reading from 0.004 to 20 mg/L. There is no electrolyte to top up.

Temperature and pressure sensors are built in and correct the reading automatically. A built-in transmitter gives two 4–20 mA outputs (DO and temperature) and RS-485 Modbus, so it wires straight to a controller or PLC. Four versions:

ST-772 – 304 stainless steel, for submersion
ST-772-P – CPVC, for submersion
ST-772T – 304 stainless steel, inline in a tee
ST-772T-P – CPVC, inline in a tee

Two-Year Membrane Cap

The DCC-1 membrane cap screws onto the flat front of the sensor and lasts about two years. Its black microporous PTFE membrane resists scratching, and the flat face is slow to foul and easy to wipe clean.

Specifications

Item	ST-772	ST-772-P	ST-772T	ST-772T-P
Part Number	53703	53720	53719	53721
Installation	Submersed	Submersed	Inline / bypass (ST-001 tee)	Inline / bypass (ST-001 tee)
Body Material	304 stainless steel	CPVC	304 stainless steel	CPVC
Wetted Materials	304 stainless steel, polycarbonate	CPVC, titanium	304 stainless steel, polycarbonate	CPVC, titanium
DO Range (4–20 mA)	0.004 – 20 mg/L, 0 – 200% saturation or 0 – 500 mbar pO₂
DO Resolution	0.01 mg/L
DO Accuracy	±0.1 mg/L or ±1%, whichever is greater
Temperature Range (4–20 mA)	0 – 50 °C (32 – 122 °F), ±0.2% of value
Method	Luminescence (fluorescence quenching), blue and red light sources
Response Time	Under 60 seconds
Outputs	Two 4–20 mA (DO and temperature) and RS-485 Modbus, 8-pin connector
Wireless	Bluetooth® with the MA-CR adapter (uPyxis® app)
Power Supply	22 – 26 V DC, 0.6 W
Operating Temperature	0 – 45 °C (32 – 113 °F)
Working Pressure	Up to 10 bar (145 psi)
Calibration	Slope: air or air-saturated water. Zero: 5% sodium sulfite or nitrogen gas
Membrane Cap	DCC-1 (P/N 53712), about 2 years' life
Dimensions	296 mm long, 33.6 mm diameter (11.65 × 1.32 in)
Weight	760 g (1.67 lb), without cable
Cables Supplied	10 m (30 ft) attached cable and 1.5 m (4.9 ft) MA-1.5CR flying-lead cable
Also Supplied	DCC-1 cap, MA-CR and MA-NEB adapters	DCC-1 cap, MA-CR and MA-NEB adapters	ST-001 tee, DCC-1 cap, MA-CR and MA-NEB adapters	ST-001 tee, DCC-1 cap, MA-CR and MA-NEB adapters
Protection	IP67 / IP68
Approvals	CE, RoHS
Compliance	USEPA 40 CFR Part 136.3 (US)

Wastewater & Aeration

Dissolved oxygen is the figure that runs an aeration basin: too little and the bacteria stop treating the waste, too much and the blowers are wasting power. An ST-772 hung in the basin gives the controller a live DO reading to run the blowers against. The same sensors suit sewage treatment, nutrient removal, process and drinking water, filtration, aquaculture and agriculture.

Key Features

0.004 – 20 mg/L, or 0 – 200% saturation, or 0 – 500 mbar oxygen partial pressure
Optical measurement, no electrolyte to replace
Built-in temperature and pressure compensation
Membrane cap lasts about two years and screws on from the front
Flat sensor face, slow to foul and easy to clean
Two 4–20 mA outputs (DO and temperature) and RS-485 Modbus
MA-CR Bluetooth^® adapter included for calibration and diagnostics in the uPyxis^® app
Calibrate in air or air-saturated water; zero in 5% sodium sulfite or nitrogen
304 stainless steel or CPVC body, IP67/IP68
Meets USEPA 40 CFR Part 136.3 (US)

Submersed – ST-772 and ST-772-P

For basins and tanks, hang the sensor from a floating or a fixed mount, both with a 1″ FNPT probe adapter:

MA-150-1 floating kit (P/N 53705) – ball float with a swivelling bracket, so the sensor rides the water level
MA-120-B fixed kit (P/N 50783) – pipe and mounting bracket at a set depth

The conduit and cable gland come from any supplier. To service the sensor, lift it straight up out of the bracket.

Inline – ST-772T and ST-772T-P

The supplied ST-001 tee has ¾” FNPT threaded or socket ends with unions, for lines up to 10 bar. Mount it so the water flows upward, which keeps bubbles off the membrane, and face the membrane cap into the flow.

Care

Check the sensor about once a month and wipe the membrane with a damp cloth or cotton bud; never use anything sharp. Store it out of the light, which shortens the life of the membrane cap.