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pHionics STs DO (Dissolved Oxygen) Transmitter

Manufacturer:
The STs Series Dissolved Oxygen combines a dissolved oxygen and temperature sensor along with a 4-20 mA transmitter into one durable, compact device.
Part Number: STS3020S-025
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$2,207.00 ex GST
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Delivery date: 2-3 weeks

All STs Series base prices include a 25 ft cable. 

Product Description

The STs Series Dissolved Oxygen combines a dissolved oxygen and temperature sensor along with a 4-20 mA transmitter into one durable, compact device.  The dissolved oxygen electrode is galvanic with a large surface area anode and a Teflon membrane, providing fast response times and low energy usage.  The large electrode tip provides the STs Series Dissolved Oxygen with a longer lifetime than typical sensors, averaging about two years.

The STs Series measures 0-20 mg/L (ppm) with an included temperature sensor measuring 0-50°C.  Automatic Temperature Compensation is provided independently of the temperature output from 0-70°C.

Isolation and differential amplification eliminate background noise and ground loops, allowing for use in a wide range of water quality monitoring and process control applications.

All parts, including the cable, are easily replaceable.

 

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, cable included, are quick and easy to replace without any special tools.  This cuts down on maintenance time and costs, especially in circumstances where cable damage otherwise requires complete replacement of traditional 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 and people 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.


2-wire, 4-20 mA Dissolved Oxygen Sensor/Transmitter

Output 4-20 mA
Dissolved Oxygen Range 0-20 mg/L (ppm)
Electrode Type Galvanic cell with Teflon membrane
Minimum Flow Rate 1.5 ft (0.457 m) per second
Automatic Temperature Compensation 2% per °C
Isolation 600 VDC
Operational Temperature Range 0-70°C
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 98% < 60 seconds
Pressure Range 0-100 psi
Wetted Materials 316 SS, Delrin, Viton, Teflon
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 ± 0.5% of full scale
Accuracy ± 2.0% of full scale
Sensitivity ± 0.05% of full scale
Stability ± 2.0% of full scale
Repeatability ± 1.0% of full scale

 

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

Output 4-20 mA
Temperature Range 0-50°C
Power Supply Voltage 8-40 VDC
Loop Impedance (Max)

200 Ohms at 12 VDC

800 Ohms at 24 VDC

1600 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 Initial Setup


pHionics STs Series Setup with HOBO RX3000


STs Series Electrode Replacement


STs Series Cable Replacement

STs Series Dissolved Oxygen FAQ

Commonly asked questions and answers regarding STs Series Dissolved Oxygen maintenance and features.

How long does a new electrode take to burn off oxygen in the cell?

New dissolved oxygen electrodes have trapped oxygen from the manufacturing process.  This trapped oxygen must be burned off before accurate measurement can be taken.  While many dissolved oxygen electrodes require multiple days, our electrodes burn off trapped oxygen within 15 minutes.

How should the electrode be stored?

The electrode should be stored dry with a protective cover over it like the rubber boot that comes in the package. Always rinse with deionized water to remove any residue remaining on the electrode.  For tough debris removal, please see our Dissolved Oxygen Care guide.

How long will the electrode last?

The standard life is 24-30 months while engaged with the transmitter, powered or not. To extend the life, disengage the electrode from the transmitter at least one full turn, or completely remove the electrode and store it.  Always protect the electrode with the provided rubber boot or similar. Unlike many dissolved oxygen electrodes, ours do not have any internal resistors or connections so they do not passively consume the electrolytes until attached to the transmitter.

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.

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?

Our dissolved oxygen electrode is a galvanic cell containing propionic acid.  It has a large surface area to allow for extremely fast response time.

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 Dissolved Oxygen Series 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 Dissoved Oxygen Electrode Care Guide for cleaning and troubleshooting procedures.

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.

All STs Series base prices include a 25 ft cable. 

Product Description

The STs Series Dissolved Oxygen combines a dissolved oxygen and temperature sensor along with a 4-20 mA transmitter into one durable, compact device.  The dissolved oxygen electrode is galvanic with a large surface area anode and a Teflon membrane, providing fast response times and low energy usage.  The large electrode tip provides the STs Series Dissolved Oxygen with a longer lifetime than typical sensors, averaging about two years.

The STs Series measures 0-20 mg/L (ppm) with an included temperature sensor measuring 0-50°C.  Automatic Temperature Compensation is provided independently of the temperature output from 0-70°C.

Isolation and differential amplification eliminate background noise and ground loops, allowing for use in a wide range of water quality monitoring and process control applications.

All parts, including the cable, are easily replaceable.

 

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, cable included, are quick and easy to replace without any special tools.  This cuts down on maintenance time and costs, especially in circumstances where cable damage otherwise requires complete replacement of traditional 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 and people 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.