Salinity Meters; How to read specifications

A salinity meter is a water quality-indicating scientific instrument used to obtain quick estimations of the amount of dissolved salt present in a water sample. There is an extensive range of salinity measuring devices available, each with different specifications. So, to help you select the best salinity meter for your application, we have put together a glossary of key terms and definitions you are bound to find in salinity meter specifications.

Salinity Unit

The most common process used by salinity meters to obtain a reading is the electrical conductivity method. Essentially, the number of ions present in a liquid influences its electrical conductivity. The more ions present, the more conductive the liquid will be, and the higher the electrical conductivity reading. The fewer ions present, the substance will be less conductive.

Salinity measuring devices produce a salinity result by finding the electrical conductivity and then applying a conversion factor.This factor is usually 0.5; however, check your device’s specifications for the specific conversion factor used.The conversion factor will take the electrical conductivity measurement and convert it to an estimated salinity measurement. The most common salinity measurement units are;

• Parts per thousand(ppt)
• Parts per million (ppm)
• Grams per litre (g/L)
• Milligrams per litre (mg/L)

Some meters can display all of the salinity units listed above, and some don’t. Again, we recommend you check the specifications to ensure your instrument will display the salinity measurement units you require.

Want to know more about the functionality of salinity meters? Check out the Instrument Choice article ‘How Does a Salinity Meter Work?’

Salinity Range

Specifications will define and display a meter’s measurement range capability as the minimum and maximum values.

Automatic Temperature Compensation (ATC)

The temperature of a solution has a significant effect on the accuracy of salinity readings. Devices with ATC have superior salinity measurement accuracy. With automatic temperature compensation (ATC), your device will automatically account for the ambient liquid temperature when taking a salinity measurement so that the meter can adjust absolute readings to determine the salinity value of the sample accurately.

Display Range/Resolution

Resolution: Refers to the smallest possible value that your instrument can display. For example, a salinity measuring device with a resolution of 0.01ppt will read to the nearest 0.01.

Operating Conditions/Temperature:

For accurate measurements, salinity measuring device specifications will detail a device’s operating temperature range. The operating range will display as a minimum and maximum temperature, sometimes with the addition of a humidity value, expressed as a percentage.

Calibration

Device specifications will outline whether or not a meter can be user-calibrated, and if so, to how many calibration points. Calibration is important to ensure accuracy, so it is essential to look for a salinity measuring device with a minimum of one calibration point.

Accuracy

Accuracy: Is the closeness of a measurement to a specific value. Specifications will express the accuracy of a device as a range, i.e., plus or minus a set amount.

Sample Rate/Time

The sample rate or sample time is the amount of time taken for the salinity meter to obtain a stable result.

Conclusion

To make searching for the perfect salinity meter for your needs as straightforward as possible, we have collated and defined the key terms you will find when searching for a salinity meter.

Need a hand finding the best salinity meter for you? Have questions about any of the definitions listed above? Contact one of the Instrument Choice Scientists. We’re here to help!

Call 1300 737 871 or email [email protected].