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pHionics STs Conductivity Sensor/Transmitter 4-20mA

pHionics has combined a conductivity and temperature sensor with a 4-20 mA transmitter into a single, compact device that provides exceptional durability and accuracy.
Part Number: STS4XXXS-025
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$2,329.00 ex GST
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Delivery date: 2-3 weeks

All STs Series base prices include a 25 ft cable. 

Product Description

pHionics has combined a conductivity and temperature sensor with a 4-20 mA transmitter into a single, compact device that provides exceptional durability and accuracy.  The 4-cell electrode with removable guard allows for easy cleaning and prevents common problems such as polarization and debris build-up that would otherwise interfere with measurements of conductivity, salinity, or total dissolved solids.  Our electrode is also made with chemical-resistant Delrin which allows us to extend our 2-year warranty to the electrode as well (The electrode and sensor/transmitter can last up to 20 years with proper care).

Combined with the small diameter (0.75”) to reduce installation costs, the features of the pHionics STs Series™ Conductivity Sensor/Transmitter guarantee accurate conductivity measurement and excellent long-term value.

Features and Benefits

Noise Reduction

From crystal-clear streams only touched by radio frequencies to wastewater treatment plants surrounded by heavy machinery, background noise and interference is everywhere.  Our signal conditioning removes background (common-mode) noise from the measurement to ensure high accuracy.  The signal is also sent through a preamplifier to strengthen it before traveling through a twisted-pair, shielded cable that protects the amplified 4-20 mA signal until it reaches the datalogger or controller.

Ease-Of-Use

Typical 2-wire transmitters are relatively easy to set up but improper wiring can result in damage to the transmitter or expensive controller.  The STs Series prevents damage with a reversible input protection so the two wires per parameter can be switched without performance issues.  Additionally, all parts are quick and easy to replace without any special tools. This cuts down on maintenance time and costs, especially in circumstances where cable damage requires complete replacement of normal sensors and transmitters.

Isolation

Isolation removes ground loop interference to save troubleshooting time and money by preventing damage to connected electronics in the case of power surges up to 600V.  This allows the STs Series to be used in process control applications without worrying about different grounding potentials of the solution or mounting surface.  It has the added benefit of protecting connected devices if exposed to large amounts of current caused by damaged machinery or improper wiring.

Low Power Usage

Sensors and transmitters made by other competitors commonly use more current than the 4-20 mA signal to power their devices, ranging from 3-15 mA additional.  pHionics only ever uses the amount of current required for the signal, allowing STs Series devices to function between 60% to 375% longer on the same battery.  The STs Series also only requires 8 VDC and has a three second turn-on time, further reducing power usage.

STs Series Initial Setup


pHionics STs Series Setup with HOBO RX3000


STs Series Electrode Replacement


STs Series Cable Replacement

2-wire, 4-20 mA Conductivity Sensor/Transmitter

Output 4-20 mA
Conductivity Range

0-100 µS

0-200 µS

0-500 µS

0-1000 µS

0-2000 µS

0-5000 µS

0-10,000 µS

0-20,000 µS

0-50,000 µS

0-100,000 µS

Electrode Type 4-cell
Automatic Temperature Compensation 2% per °C
Isolation 600 VDC
Power Supply Voltage 8-40 VDC
Loop Impedance (Max)

200 Ohms at 12 VDC

800 Ohms at 24 VDC

1600 Ohms at 40 VDC

Response time 95% < 5 seconds
Pressure Range 0-100 psi
Wetted Materials 316 SS, Delrin, Viton, glass
Length 13.5 in (34.3 cm)
Width 0.750 in (1.9 cm) maximum
Weight (No cable) 0.50 lbs (0.227 kg)
Linearity ± 0.20% of full scale
Accuracy ± 0.20% of full scale
Sensitivity ± 0.05% of full scale
Stability ± 0.10% of full scale
Repeatability ± 0.10% of full scale

 

2-wire, 4-20 mA Temperature Sensor/Transmitter

Output 4-20 mA
Temperature Range 0-50°C
Power Supply Voltage 7-40 VDC
Loop Impedance (Max)

250 Ohms at 12 VDC

850 Ohms at 24 VDC

1650 Ohms at 40 VDC

Isolation 600 VDC

 

Cable

Cable Material Polyurethane
Type 4 conductor, Kevlar reinforced, water blocked, shielded, twisted-pair wiring
Maximum Distance 3 miles
Replaceable? Yes

STs Series Conductivity FAQ

Answers to common questions regarding STs Series Conductivity care, features, and recommendations

How should the electrode be stored?

The electrode should be stored dry with the electrode guard on for protection.  Before storage, rinse the electrode and interior of the conductivity guard to remove debris.  A soft brush can also be used to for any debris that remains stuck on the electrode.

How long does the electrode last?

Our conductivity electrode is exceptionally durable and can last between 5 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 but normally the electrode is excluded. For STs Series Conductivity electrodes, we also extend the two year warranty to 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.

How can the STs Series be installed/mounted?

The STs Series can be mounted in-line using the optional 1.0″ NTP PVDF DIN Connector, immersed with compression fitting in a 3/4″ pipe, or freely suspended by the Kevlar™ cable. 

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, which is why we offer the option of 316 Stainless-steel or titanium for the metal housing and PVDF (standard) or Delrin for the plastic.  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 combined sensor/transmitter is always recommended so a replacement for every part is available at any time.  A duplicate simplifies troubleshooting by always having a functional STs Series available.  It also allows for swapping of devices during calibration and cleaning, so measurement is not significantly disrupted.  At a minimum, a spare electrode is recommended in the event of damage or eventual replacement. 

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

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.

All STs Series base prices include a 25 ft cable. 

Product Description

pHionics has combined a conductivity and temperature sensor with a 4-20 mA transmitter into a single, compact device that provides exceptional durability and accuracy.  The 4-cell electrode with removable guard allows for easy cleaning and prevents common problems such as polarization and debris build-up that would otherwise interfere with measurements of conductivity, salinity, or total dissolved solids.  Our electrode is also made with chemical-resistant Delrin which allows us to extend our 2-year warranty to the electrode as well (The electrode and sensor/transmitter can last up to 20 years with proper care).

Combined with the small diameter (0.75”) to reduce installation costs, the features of the pHionics STs Series™ Conductivity Sensor/Transmitter guarantee accurate conductivity measurement and excellent long-term value.

Features and Benefits

Noise Reduction

From crystal-clear streams only touched by radio frequencies to wastewater treatment plants surrounded by heavy machinery, background noise and interference is everywhere.  Our signal conditioning removes background (common-mode) noise from the measurement to ensure high accuracy.  The signal is also sent through a preamplifier to strengthen it before traveling through a twisted-pair, shielded cable that protects the amplified 4-20 mA signal until it reaches the datalogger or controller.

Ease-Of-Use

Typical 2-wire transmitters are relatively easy to set up but improper wiring can result in damage to the transmitter or expensive controller.  The STs Series prevents damage with a reversible input protection so the two wires per parameter can be switched without performance issues.  Additionally, all parts are quick and easy to replace without any special tools. This cuts down on maintenance time and costs, especially in circumstances where cable damage requires complete replacement of normal sensors and transmitters.

Isolation

Isolation removes ground loop interference to save troubleshooting time and money by preventing damage to connected electronics in the case of power surges up to 600V.  This allows the STs Series to be used in process control applications without worrying about different grounding potentials of the solution or mounting surface.  It has the added benefit of protecting connected devices if exposed to large amounts of current caused by damaged machinery or improper wiring.

Low Power Usage

Sensors and transmitters made by other competitors commonly use more current than the 4-20 mA signal to power their devices, ranging from 3-15 mA additional.  pHionics only ever uses the amount of current required for the signal, allowing STs Series devices to function between 60% to 375% longer on the same battery.  The STs Series also only requires 8 VDC and has a three second turn-on time, further reducing power usage.