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ST-720 & ST-726 High Range Conductivity Sensors
- Product Details
- Specifications
- Industrial Water & Wastewater
- Installation
- Video
ST-720 & ST-726 High Range Conductivity Sensors
The Pyxis ST-720 and ST-726 are inline conductivity sensors for water that carries a lot of dissolved salts. Each has its own transmitter and temperature sensor, so it wires straight to a controller, PLC or DCS with no separate meter.
- ST-720 – 1 to 100,000 µS/cm
- ST-726 – 10 to 300,000 µS/cm
Both give two 4–20 mA outputs, one for conductivity and one for temperature, plus RS-485 Modbus. The reading is corrected to 25 °C by a built-in Pt100 sensor, and accuracy is ±10 µS/cm or 1.5%.
Four Graphite Electrodes
The sensors measure with four graphite electrodes set in a flat face. The design is less prone to fouling and deposits, so the reading holds without frequent calibration, and the flat face makes cleaning easy.
Specifications
| Item | ST-720 | ST-726 |
|---|---|---|
| Part Number | 53101 | 53114 |
| Conductivity Range (4–20 mA) | 1 – 100,000 µS/cm | 10 – 300,000 µS/cm |
| Conductivity Accuracy | ±10 µS/cm or 1.5% | |
| Temperature Range (4–20 mA) | 0 – 100 °C (32 – 212 °F), ±0.2% of value | |
| Temperature Compensation | Built-in Pt100 RTD, to 25 °C | |
| Electrodes | Four graphite electrodes | |
| Cell Constant (K) | 0.3 | |
| Outputs | Two 4–20 mA (conductivity and temperature) and RS-485 Modbus, 7-pin connector | |
| Wireless | Bluetooth® with the MA-WB or PowerPACK adapter (uPyxis® app) | |
| Power Supply | 12 – 36 V DC, 1 W | |
| Sample Temperature | 0 – 49 °C (32 – 120 °F) | |
| Sample Pressure | 0 – 6.9 bar (0 – 100 psi) | |
| Storage Temperature | −20 – 60 °C (−4 – 140 °F) | |
| Inline Installation | ST-001 tee supplied, ¾" FNPT socket or thread with union | |
| Submersed Installation | MA-102S submersion adapter (optional) | |
| Body Material | CPVC | |
| Dimensions | 172 mm long, 36 mm diameter (6.8 × 1.44 in) | |
| Cable | 1.5 m (5 ft) attached cable with 7-pin connector, plus 1.5 m (5 ft) MA-1100 flying-lead cable | |
| Protection | IP67 | |
| Approvals | CE, RoHS | |
Industrial Water & Wastewater
Conductivity is the quickest measure of how much is dissolved in water. The ST-720 covers most industrial and process water, and the ST-726 goes on to very high-conductivity streams. Both also suit surface water, wastewater and stormwater monitoring, fitted inline in a tee or submersed with an adapter.
Key Features
- Wide ranges: 1 – 100,000 µS/cm (ST-720) and 10 – 300,000 µS/cm (ST-726)
- Four graphite electrodes, resistant to fouling and deposits
- Built-in Pt100 temperature sensor, reading corrected to 25 °C
- Built-in transmitter, no separate meter needed
- Two 4–20 mA outputs (conductivity and temperature) and RS-485 Modbus
- Calibration and diagnostics over Bluetooth® with the MA-WB or PowerPACK adapter and the uPyxis® app
- Runs on 12 – 36 V DC, 1 W
- CPVC body, IP67, supplied with the ST-001 ¾” FNPT inline tee
Inline or Submersed
Each sensor comes with the ST-001 tee, ¾” FNPT socket or thread with a union, for a sample line up to 6.9 bar and 49 °C. For tanks and channels, the optional MA-102S adapter (1½” NPT) lets it be submersed.
Cleaning & Calibration
How often depends on the water: suspended solids, iron, manganese, oil and bacteria all add to it. Soak the lower half of the sensor in Pyxis cleaning solution for 5 – 10 minutes, brush it lightly and rinse with distilled water. Pyxis conductivity standards of 1,000 and 50,000 µS/cm suit calibration in the uPyxis® app.
The 4–20 mA conductivity output is set to the full range at the factory. The top of the scale can be lowered in the app, but not raised.