STs Series pH Sensor

Highlighted Features

Combination double-junction electrode measuring 0 to 14 pH
Large reference half-cell to reduce calibration frequency
Secondary 0-50°C temperature sensor
2-wire, 4-20 mA analog outputs compatible with wide range of dataloggers or remote telemetry units (RTU)
Narrow diameter (0.75 inches or 1.9 cm) for groundwater monitoring applications 
Low power usage

Ranges available:

0-14 pH
6-11 pH

For datalogging applications, we recommend pairing our devices with the HOBO RX3000.

Description

The pHionics STs Series™ pH is a dual-output sensor that pairs with a datalogger or RTU for real-time water quality monitoring. A narrow diameter allows the STs Series to go where other sensors cannot while a durable, chemical-resistant housing ensures many years in-use.

All parts, including the cable, are easily replaceable without tools using pHionics patented pHiConn™ System, saving frustration and money.

In addition, isolation, differential amplification, and shielding ensure a strong signal with high signal-noise ratios, all while remaining low-power.

These features make our pH sensor well-suited for applications such as groundwater monitoring, wastewater treatment, aquaculture, pollution monitoring, etc.

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Starting at $930 USD

All STs Series base prices include a 25 ft. (7.62 m) cable. Custom cable lengths available.

Pricing

Please see our STs Series pH Sensor Price List for more information on available options and pricing. Our spare parts pricing is available here.

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Business hours:

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Full Features List

Combination double-junction electrode with large reference reservoir
Secondary 0-50°C temperature sensor 
Chemical-resistant Delrin®, PVDF, and 316 Stainless Steel housing (Titanium optional) 
Narrow diameter (0.75 inches or 1.9 cm) 
Removable electrode guard to protect from damage while allowing access to electrode for cleaning
Fully submersible up to 70 psi 
Shielded, Kevlar®-reinforced, water-blocked polyurethane cable 
4-20 mA signal capable of transmission up to 3 miles (with proper wire gauge) 
Automatic Temperature Compensation (2% per degree Celsius) 
Reversible Input Protection and Operation 
2-second warm-up time to avoid battery drain of datalogger or RTU
Low power usage for long-term water quality monitoring
Isolated to prevent ground loops 
Signal conditioning to remove background noise

Low Maintenance

The weak point of pH sensors is their reference solution, which gets diluted by the sample over time.  STs Series pH sensors mitigate this problem by incorporating a reference half cell with a large reservoir.  The high volume, combined with a low-flow reference gel and double-junction, reduces the dilution rate to provide a more stable reference.

Accurate Measurements

No noise. No nonsense.

Experience the difference with our proprietary noise reduction technology.

Specifications

pH Sensor

Output	4-20 mA
pH Range	0-14 pH
Operational Temperature Range	0-70°C
Electrode Type	Silver/silver chloride, double junction, replaceable gel electrode
Transmitter Type	2-wire
Pressure Range	0-70 psi
Automatic Temperature Compensation	0-70°C
Isolation	600 VDC
Power Supply Voltage	8-40 VDC
Warm-up Time	2 seconds
Response time	95% < 5 seconds
Wetted Materials	316 Stainless Steel, Delrin®, Viton™, glass, epoxy
Length	14.25 in (36.20 cm)
Width	0.750 in (1.9 cm) maximum
Weight (No cable)	0.50 lbs (0.227 kg)
Linearity	±0.014 pH*
Accuracy	±0.014 pH*
Sensitivity	±0.01 pH
Stability	±0.03 pH per year
Repeatability	±0.01 pH

*After proper calibration

Temperature Sensor

Output	4-20 mA
Temperature Range	0-50°C
Accuracy	+/- 1°C
Linearity	+/- 0.5°C
Power Supply Voltage	7-40 VDC

Cable

Cable Material	Polyurethane
Type	4 conductor, Kevlar® reinforced, water blocked, shielded, twisted-pair wiring
Maximum Distance	3 miles
Resistance per 1000 ft (304.8 m)	26 Ohms
Replaceable?	Yes