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ST-765SS & ST-765P Oxidizer and pH Sensors
- Product Details
- Specifications
- Installation
- Video
ST-765SS & ST-765P Oxidizer and pH Sensors
Chlorine, pH and Temperature from One Sensor, No Reagents
The Pyxis ST-765 sensors measure an oxidiser such as free chlorine, together with pH and temperature, continuously and without reagents or membranes. They use bare gold electrodes, and correct the oxidiser reading for pH and temperature automatically, so the result follows the DPD laboratory method up to pH 9.
Two Bodies
- ST-765SS – stainless steel: for cooling, process and industrial water as well as drinking water. Twelve versions: free or total chlorine, chlorine dioxide, bromine, monochloramine, ozone, hydrogen peroxide, peracetic acid, sulfite, DBNPA, dechlorination (free chlorine + sulfite) and free + total chlorine.
- ST-765P – CPVC: for clean water such as drinking water and RO feed. Four versions: free chlorine, chlorine dioxide, ozone and dechlorination.
Simple Maintenance
The flat sensor face resists fouling and is easy to clean. The electrode head (EH-765) screws on from the front and lasts up to about two years. Each sensor gives two 4–20 mA outputs (oxidiser and pH) and RS-485 Modbus, and can be calibrated over Bluetooth® from the uPyxis® app.
Specifications
| Item | ST-765SS | ST-765P |
|---|---|---|
| Body | 316L stainless steel | CPVC |
| Versions | 12 (see table below) | 4: free chlorine, chlorine dioxide, ozone, dechlorination |
| Best For | Cooling, process, industrial and drinking water | Clean water: drinking water, RO feed |
| pH Range | 0 – 14, ±0.01 pH | |
| Compensation | Temperature (built-in RTD) and pH, up to pH 9 | |
| Outputs | Two isolated 4–20 mA (oxidiser and pH) and isolated RS-485 Modbus | |
| Wireless | Bluetooth® with the MA-CR or PowerPACK adapter (uPyxis® app) | |
| Power Supply | 22 – 26 V DC, 2 W | |
| Sample Inlet Pressure | 0.5 – 2 bar | |
| Maximum Sensor Pressure | 6.9 bar | |
| Operating Temperature | 4 – 49 °C | 4 – 40 °C |
| Storage Temperature | −7 – 60 °C | |
| Dimensions | 211 mm long, 36 mm diameter | |
| Weight | 530 g | |
| Protection | IP67 | Not stated |
| Compliance | US EPA 334.0, ISO 7393; CE, RoHS | |
| Electrode | Replaceable EH-765 head, about 2 years' life | |
| Cables Included | 1.5 m 8-pin cable and flying-lead cable | |
| Warranty | Sensor 13 months; electrode 6 months | |
Versions and Ranges
| Version | Measures | Range | Precision | ST-765SS Part No. | ST-765P Part No. |
|---|---|---|---|---|---|
| FCL | Free chlorine | 0 – 5 ppm | ±0.01 mg/L or 1% | 53607 | 53619 |
| TCL | Total chlorine | 0 – 5 ppm | ±0.01 mg/L or 1% | 53616 | – |
| CLO | Chlorine dioxide | 0 – 5 ppm | ±0.01 mg/L or 1% | 53608 | 58861 |
| Br | Bromine | 0 – 5 ppm | ±0.01 mg/L or 1% | 59643 | – |
| NCL | Monochloramine | 0 – 5 ppm | ±0.01 mg/L or 1% | 53623 | – |
| O3 | Ozone | 0 – 2 ppm | ±0.01 mg/L or 1% | 53614 | 54485 |
| H2O2 | Hydrogen peroxide | 0 – 200 ppm | ±0.2 mg/L or 1% | 53612 | – |
| PAA | Peracetic acid | 0 – 100 ppm | ±0.2 ppm or 5% | 53610 | – |
| SO3 | Sulfite | 0 – 5 ppm (up to 0 – 100 ppm) | ±1 mg/L or 1% on the wide range | 53624 | – |
| DCL | Free chlorine + sulfite (dechlorination) | 0 – 5 ppm + 0 – 100 ppm | ±0.01 mg/L or 1% (chlorine) | 58444 | 59907 |
| TFCL | Free chlorine + total chlorine | 0 – 5 ppm + 0 – 5 ppm | ±0.01 mg/L or 1% | 55994 | – |
| DBNPA | DBNPA biocide | Ask CHEMTROL® | – | 54267 | – |
The oxidiser measurement is not selective: other oxidisers in the water add to the reading.
Clean Water
For drinking water and other clean water, the sensor fits the ST-007 inline tee or the FR-50 flow reservoir, which comes with a rotameter and pressure-reducing valve. Both are sold separately; fit the tee after a rotameter to set the sample flow.
Dirty and Industrial Water
For cooling towers, process water and other dirty water, Pyxis requires the FR-300-PLUS auto-brushing flow reservoir. A motorised brush keeps the sensor face clean continuously. Sample flow 200 – 800 mL/min, ⅜” OD tube inlet and outlet, 24 V DC.
Sample Conditions
- Sample inlet pressure 0.5 – 2 bar
- Water temperature 4 – 49 °C
- Calibrate oxidiser and pH from the uPyxis® app with the MA-CR or PowerPACK Bluetooth® adapter
Applications
- Drinking water and secondary water supply
- Cooling water and industrial process water
- RO feed water and dechlorination
- Wastewater effluent
- Food and beverage process water and sanitising
- Irrigation water
