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Technical Specifications
The pHionics STs Series combines continuous pH measurement with a secondary temperature output for integration with data loggers, telemetry systems, PLCs and SCADA networks.
| pH range | 0–14 pH |
|---|---|
| Output | 4–20 mA |
| Transmitter type | True 2-wire transmitter |
| Electrode type | Replaceable silver/silver-chloride, double-junction gel electrode |
| Operational temperature | 0–70°C (32–158°F) |
| Automatic temperature compensation | 0–70°C |
| Accuracy | ±0.014 pH after proper calibration |
| Linearity | ±0.014 pH after proper calibration |
| Sensitivity | ±0.01 pH |
| Repeatability | ±0.01 pH |
| Long-term stability | ±0.03 pH per year |
| Response time | 95% in less than 5 seconds |
| Warm-up time | 2 seconds |
| Temperature output | Separate 4–20 mA output |
|---|---|
| Measurement range | 0–50°C (32–122°F) |
| Accuracy | ±1°C |
| Linearity | ±0.5°C |
| Supply voltage | 7–40 VDC |
| pH transmitter supply voltage | 8–40 VDC |
|---|---|
| Electrical isolation | 600 VDC |
| Pressure rating | 0–70 psi; fully submersible |
| Wetted materials | 316 stainless steel, PVDF, Viton™ and glass |
| Housing option | Titanium available for demanding environments |
| Length | 14.25 in (36.20 cm) |
| Maximum diameter | 0.75 in (1.9 cm) |
| Weight without cable | 0.50 lb (0.227 kg) |
| Cable construction | Four-conductor, shielded, twisted-pair polyurethane cable; Kevlar® reinforced and water blocked |
|---|---|
| Maximum signal distance | Up to 3 miles with the proper wire gauge |
| Cable resistance | 26 ohms per 1,000 ft (304.8 m) |
| Replaceable cable | Yes |
pH Monitoring Applications
Designed for continuous pH and temperature measurement in field, municipal and industrial water-monitoring systems.
Wastewater Treatment
Treatment basins, process streams, influent and final-effluent monitoring.
Surface Water Monitoring
Rivers, lakes, canals and watershed monitoring stations.
Industrial Process Water
Process control, discharge monitoring and industrial water treatment.
Agriculture & Irrigation
Irrigation water, nutrient solutions, agricultural runoff and water quality.
Environmental Remediation
Groundwater remediation, cleanup projects and environmental compliance.
Aquaculture
Fish farms, hatcheries, recirculating systems and aquatic research.
Municipal Water Systems
Water-treatment infrastructure, storage systems and compliance stations.
Remote Monitoring
Data loggers, RTUs, cellular telemetry, PLCs and SCADA systems.
Why Choose the STs Series™ pH Sensor
Built-To-Last
With proper care, these sensors are designed for many years of reliable pH monitoring in harsh conditions. The truly unique aspect of the STs Series is that every part, including the cable, is easily replaceable in the event of wear/damage. This considerably extends their lifespan to save your company money. It also keeps waste out of landfills to support sustainable business practices.
Ground Loop Elimination
If you ever have a pH sensor sending erratic measurements and can’t figure out why, then there may be a “ground loop”. A ground loop occurs when the electrical circuit has multiple paths to ground that cause interference. This issue can be very difficult to detect and fix. The best way to avoid ground loops is with input/output electrical isolation, which is built into every pHionics sensor.
Low Maintenance
Very little is required to keep these sensors up. Just perform periodic calibrations and replace the electrode every few years*. Electrode replacement is a 60-second procedure that is easily performed in the field without any tools.
