The pHionics STs Series™ Conductivity is a water quality sensor designed to pair with a datalogger or RTU for real-time data capture. A narrow diameter allows the STs Series to go places others can’t while the chemical-resistant housing ensures the sensor can stay there for many years. Proprietary electrode technology provides stable measurements to reduce calibration frequency.

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 conductivity sensor well-suited for applications such as groundwater monitoring, wastewater treatment, aquaculture, pollution monitoring, etc.

Conductivity Sensor Ranges Available:

• 0-100 µS/cm
• 0-200 µS/cm
• 0-500 µS/cm
• 0-1000 µS/cm
• 0-2000 µS/cm
• 0-5000 µS/cm
• 0-10,000 µS/cm
• 0-20,000 µS/cm
• 0-50,000 µS/cm
• 0-100,000 µS/cm

Low Maintenance

Reduce the number of site visits with the STs Series Conductivity sensor. A 4-cell electrode holds calibration for long periods of time while also preventing errors due to polarization.

In addition, the guard protects the sensing elements from algae and debris build-up, further reducing the need for calibration.

Applications

• Groundwater Monitoring
• Saltwater intrusion
• Agricultural Runoff
• Mining Pollution
• Industrial Effluent Monitoring
• Wastewater Treatment
• Environmental Remediation
• Aquaculture

*After proper calibration

How should the sensor be stored?

Please see our STs Series Storage guide >>

How long does the electrode last?

Our conductivity electrode is exceptionally durable and can last between 10 and 20 years assuming proper care and use in an application that will not attack the electrode cells.  See our guide on Conductivity Electrode Care for more information.

Is the output automatically temperature-compensated (ATC)?

The output is adjusted by 2% per °C relative to 25°C.  A thermistor within the housing is used which is why the ATC is most accurate when the device is fully submersed.  ATC functions regardless of whether the temperature output is in use.

Do you provide a warranty?

Yes, our products come with a 2-year warranty, excluding the electrode. These products are designed to last far longer if properly cared for and we will do what we can to help if any problems occur in or out of warranty.  Please don’t hesitate to reach out!

Read our full warranty here >>

What voltage is required for the STs Series Conductivity?

An 8VDC power supply is sufficient with standard lengths of cable.  Voltage drop must be accounted for over long lengths of cable (50+ ft.) to ensure enough power is supplied to any water quality sensor.  To calculate it, first double the length of cable to get the account for the full length of the circuit, then multiply that by resistance per foot/meter to get total resistance.  pHionics uses 24 AWG tinned-copper wire which has a resistance of 0.026 ohms per foot (0.084 ohms per meter).  Multiply total resistance by the maximum expected current (20 mA, or 0.02 A, is safest) to obtain expected voltage drop.  Verify that the voltage drop plus required voltage for pHionics sensors (8 VDC) is less than the power supply voltage.

How long are STs Series devices expected to last?

While the electrode will require replacement every three years on average, the housing, seals, and cables are intended to last 10-20 years with proper care. To increase longevity of the seals, the Viton O-rings should be relubricated with a silicon grease during each disassembly, or at least inspected for any debris or damage.  The harshness of the solution (high/low pH, extreme salinity, high pressure, etc.) also affects longevity.  All parts are replaceable to save money and limit waste in the event that any piece gets damaged.

What type of electrode is provided?

pHionics conductivity electrodes use a four-cell technique for high accuracy.  The electrodes are made of Delrin and the cells out of 316 stainless steel or titanium.  The electrode guard should always be on during measurement because it provides greater accuracy.

What spare parts are recommended?

For critical measurements, a duplicate STs Series sensor is always recommended so a replacement for every part is always available.  A duplicate simplifies troubleshooting by having a functional STs Series on-hand to compare results.  It also allows for swapping of devices during calibration and cleaning so the measurement or process is not significantly disrupted.  At a minimum, a spare electrode is recommended in the event of damage–or the need for eventual replacement.  This is especially important when waiting for a replacement to be shipped could be detrimental to your application.

How often should the STs Series pH be calibrated and/or cleaned?

The frequency of calibration must be determined empirically as rate of drift and debris accumulation differs for each application. Calculating the offset during calibration provides information on whether the electrode is still viable.  See our article on Proper Sensor Calibration for assistance in the process.  Check out our pH Electrode Care Guide for cleaning and troubleshooting procedures.

How can the STs Series be installed/mounted?

The STs Series can be mounted in-line or immersed with the cmp-k compression fitting in a 3/4″ pipe, or freely suspended by the Kevlar™ cable.  Please see the pHionics STs Series Device Manual or contact us for more information.