Conductivity Sensors
Why Measure Conductivity On-line?
Conductivity is a general measurement of the dissolved acids, bases, salts, and other dissolved solids in a liquid solution. Electrical conductivity is a good indication of purity (or lack there of) of the liquid. For this reason, it is commonly used in pure water measurements to determine the presence of contaminants. Conductivity is also an effective tool to measure the concentration of an acid or a base. The relationship of the concentration addition of an acid or base to pure water can be charted by a well defined curve of conductivity versus concentration. These measurements are often used to create solutions such as NaOH for clean-in-place applications.
2-Pole
Ultrapure water to mid-range conductivity applications with clean liquids where corrosion or build-up is not a concern.
4-Pole
Designed for wide range of conductivity measurements found in chromatography, filtration, and chemical blending applications.
Inductive
Inductive conductivity sensors are ideal for applications with moderate to high conductivity levels as well as high potential for fouling.
Which conductivity sensor style is right for me?
Selection of conductivity sensors is highly dependent on the application and measurement range. There are three main technologies to currently available to choose from.
2-Pole Conductivity
Relies on two stainless steel electrodes to measure conductivity. Range is controlled using the cell constant of the sensor. Very common, well known technology that works with most existing transmitters on the market.
4-Pole Conductivity
Uses one pair of metallic electrodes to measure and a second pair to vary drive voltage. The design offers high accuracy over a very large measurement range in a small 12 mm sensor format.
Inductive Conductivity
Embedded toroids within the plastic sensor body are used to measure conductivity. The design solves corrosion and coating issues since no metal electrodes are exposed. These sensors are physically larger and require a dedicated transmitter.
Specifications
| Conducell UPW | Conducell 2DC | Conducell 4UxF | Conducell 4US | Conducell I | |
|---|---|---|---|---|---|
| Measuring Range | 0.01 - 1500 µS/cm | 10 µS/cm - 20 mS/cm | 1 µS/cm - 300 mS/cm | 0.1 µS/cm - 500 mS/cm | 100 µS/cm - 2000 mS/cm |
| Measurement Principle | 2-pole | 2-pole | 4-pole | 4-pole | Inductive |
| Operating Temperature Range | -10 - 140 °C (Arc: analog 0 – 110 °C, digital 0 – 130 °C) |
-5 – 80 °C | -20 – 150 °C (Arc: analog 0 – 110 °C, digital 0 – 130 °C) |
-20 – 135 °C | -10 – 125 °C |
| Pressure Range (bar g) | 0 – 10 bar (130 °C) | 0 – 6 bar | -1 – 20 bar (135 °C) -1 - 10 bar (140 °C) |
0 – 6 bar | 0 – 8 bar (125 °C) 0 - 12 bar (90 °C) |
| Hygienic Aspects | Autoclavable, CIP, SIP | -- | Autoclavable, CIP, SIP | CIP, SIP | CIP, SIP |
| Cell Constant | < 0.1/cm | 1/cm | 0.36/cm | 0.147/cm | 6.3/cm |
| Electrode Material | Stainless Steel 1.4435 | Graphite | S=Stainless Steel 1.4435 H=Stainless Steel 2.4602 T=Titanium Pt=Platinum |
Stainless Steel 1.4435 | Toroids (embedded in PEEK Body) |
| O-ring | EPDM | EPDM | EPDM | EPDM | -- |
Specific Applications
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App Note - Intelligent Sensor in Pure Water Production
Arc sensors for conductivity, pH and ORP measurement in pure water treatment
Resources
Hamilton's knowledge base provides a range of explanatory articles, frequently asked questions, and document downloads.
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Brochure - BioPharma
Innovative solutions for process analytics in biotechnological and pharmaceutical industries. -
Flyer - Conducell UPW
Overview of the features of the conductivity sensor Conducell UPW for Ultra pure water applications. -
Manual - Conducell 4UxF Sensors
Manual for Conducell 4UxF sensors.
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Does temperature affect conductivity measurement?
Yes, temperature has a direct impact on conductivity. Increasing temperature increases the mobility of ions within a solution and results in higher conductivity measurements. Temperature compensation can be performed using empirically derived temperature coefficients, which may be different for various solutions. -
Which liquid conductivity standard should I use for calibration?
A conductivity standard should be chosen that most closely matches the anticipated conductivity range of the process. -
Where can I find documentation and certificates for my sensors?
Paper copies sensor information such as manuals, declarations of quality, and material certificates ship with the product. Hamilton also has several website resources to find related information. Click on the FAQ to learn more.
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Conductivity Knowledge Base Articles
A summary page with links for all conductivity related articles -
Conductivity Sensor Selection
There at three basic styles of conductivity sensors. This article discusses which products are the best fit for the application. -
How to Measure Sensor A-length
Sensor A-length determines the insertion depth of the sensor. This article shows how this measurement is made for various styles of sensors.
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