Mod-EC

Summary | Use | Design | Ask a question | FAQ

Datasheet 📜

ℹ️ Summary

  • EC range of 0.05 µS/cm to 1 S/cm with appropriate probe
  • Accuracy ±0.002  mS/cm
  • Resolution 0.001 mS/cm
  • Temperature compensated
  • I²C, UART, and USB interfaces
  • 1-Wire interface for DS18B20 temperature sensor
  • 25x15 mm for castellated or DIP mounting
  • Single, dual, and triple point calibration

🚀 Use


✒️ Design

Adding a module to your own design is straightforward. You'll need:

  1. bus connection to your controlling device (I2C, UART, USB)
  2. clean, isolated, power supply
  3. probe connection (U.FL, BNC, terminal block)

Some resources to get started:

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🤙 Ask a question


🤔 FAQ

Can I keep the probes in water all the time?

The short answer is yes, you can.

The longer answer is yes, but make sure you know the pros and cons. You can leave any probe submerged in water, in fact, the industrial versions are designed for exactly that. The lab versions are primarily designed for use and then storage, but can also be submerged.

For EC probes, there really isn't anything bad that can happen to them from continuous submersion. There is nothing in their design that will degrade. If you frequently submerge and then remove them, you'll need to ensure they are cleaned and they don't develop calcium/hard water deposits as the water dries. These deposits may not dissolve very easily when the probe goes back in the water and will alter the readings.

Do I need isolation?

Yes.

The longer answer: You probably do. Cases where you definately will need isolation include using another EC, pH or ORP probe and when other electrical elements are in the tank (pumps, heaters, contact mixers). You may not need it in a small beaker with nothing else in it.

Isolation through Microfire devices also provides a stable power supply which is vital for accurate measurements, so even if you feel like isolation isn't needed, it may be a better choice to use it for the stability, and you also gain isolation for some unplanned for use-case that would require isolation.

How long should I go between recalibration?

There are a lot of factors involved in this one. It depends on how roughly the probes are being used. Are they subject to large temperature swings, harsh chemicals, fast flowing water, or drying cycles? All of those things will contribute to a faster recalibration schedule.

How accurate do you need your measurements to be? With light use, you might not see a measurement move more than a few tenths in several months. Is that within your error budget? Only you can say, given your specific application requirements and specific set of environmental factors. We can give general guidelines, but there is no simple, accurate answer.

When is temperature compensation needed?

For EC, it is required.

Each C degree of temperature change will also change your EC reading by around 2% (in freshwater). Compensation formulas have been developed that are a good approxiation.

What conductivity cell-constant do I need?

Cell constants are most commonly 0.1, 1.0, and 10.0 and denoted by K. Changing the cell constant of the probe allows for the same device to measure in different ranges. The exact ranges are dependent on the hardware, so for this answer, Microfire's Mod-EC will be used.

  • For measuring ultra-pure water (0.05 to 100 microsiemens), a cell-constant of 0.1 K, or even 0.01 K is used. Ultra-pure water might be pure water, which cannot go lower than about 0.05 microsiemens, to RO/DI water, or maybe even distilled.
  • For measuring freshwater, drinking water, hydroponics solutions (100 microsiemens to 10 millisiemens), a cell constant of 1 K is used.
  • For seawater, brackish, or brine (10 millisiemens to 1 Siemen), a cell-constant of 10 K is used.