Views: 206 Author: Yammi Publish Time: 2024-02-06 Origin: Site
Salinity is an important concept in seawater; seawater salinity is the ratio of all dissolved solids in seawater to the weight of the seawater. More than simply evaporating seawater and weighing the mass of dry salt is not an accurate measurement of the salt content of a body of water. We usually use a salinity meter to measure the practical salinity of water (PSU). Please read on if you would like to learn more about the salinity meter.
The salinity meter is a device used to measure salt concentration in water. It is commonly used in industries such as aquaculture, environmental monitoring and food processing, as well as in scientific research and educational settings.
Meaning of Salinity:
Salinity is the concentration or content of dissolved salts in water. It expresses the amount of dissolved salts in the water, usually expressed as salts/kg (ppt) or percentage (%).
The salinity of a water body is important for aquaculture as it maintains the osmotic pressure stability of aquaculture animals and also provides essential mineral nutrients for aquaculture animals, algae, microbial aquatic organisms, etc., and also has an impact on the various physicochemical properties of the water body (e.g., dissolved oxygen).
Using a salinity meter is a straightforward process, but the specific steps may vary slightly depending on the type of salinity meter you have. There are handheld meters, benchtop meters, and even digital probes that can be used. Here is a general guide on how to use a handheld salinity meter:
Calibration:
Before using the meter, it's crucial to calibrate it using a standard calibration solution. This solution should have a known salinity level.
Follow the manufacturer's instructions for calibration, which usually involve placing the meter in the calibration solution and adjusting the device until it reads the correct value.
Sample Preparation:
Collect a water sample that you want to measure. Ensure that the sample is representative of the area you are interested in, and it should be free from any contaminants.
Meter Setup:
Turn on the salinity meter and allow it to stabilize according to the manufacturer's guidelines. Some meters may need a few minutes to warm up
Reading a salinity meter involves interpreting the measurement displayed on the device. Here are general steps on how to read a salinity meter:
Digital Display:
Most modern salinity meters have digital displays that directly show the salinity value in parts per thousand (ppt), practical salinity units (PSU), or other relevant units.
Read the numerical value displayed on the screen. This is the salinity level of the water sample.
Analog Scale:
Some older or simpler salinity meters may have an analog scale or a needle indicator.
Check the position of the needle or marker on the scale. The point where it aligns indicates the salinity level.
Unit of Measurement:
Make sure to note the unit of measurement used by the salinity meter. Common units include parts per thousand (ppt), practical salinity units (PSU), or specific gravity.
Understand the conversion factor if necessary. For example, 1 PSU is approximately equal to 1 ppt.
Temperature Consideration:
Some salinity meters may compensate for temperature, and the displayed value may be adjusted based on the temperature of the water sample.
Ensure that the temperature compensation is either turned off if you want a raw reading or is set to the appropriate temperature if compensation is desired.
Recording the Reading:
Record the salinity reading for future reference or analysis.
If you are conducting multiple measurements, rinse the probe with distilled water between samples to avoid contamination.
The Salinity meter's sensor or electrode measures the conductivity of water by direct contact with the sample.
Calibration: The accuracy of the salinity meter is ensured by calibrating it with a standard solution of known salinity level before use.
Measurement: The salinometer is inserted into the water sample, and the electrodes come into contact with the ions in the water; the conductivity of the water affects the current through the electrodes.
Convert to Salinity: The salinometer converts the conductivity reading to a salinity measurement, usually expressed in units such as parts per thousand (ppt), practical salinity units (PSU) or specific gravity.
Display: The converted salinity measurement is displayed on the meter's screen.
Temperature Compensation: Some salinometers have a temperature compensation feature to correct for the effects of temperature on conductivity.
Cleaning and Maintenance: The electrodes of the salinometer are cleaned and maintained regularly to ensure accuracy and prolong service life.
The tools commonly used to measure the salinity of seawater are generally divided into electronic salinometers for conductivity and refractive salinometers.
The solute in the solution will be electrolyzed into various anions and cations; this type of salinity meter measures the conductivity to convert it into salt content.
There are mainly 3 kinds of results in the form of expression: ppt, PSU, S.G. (20/20)
1: ppt (parts per thousand): salinity in parts per thousand; this is the second most commonly used unit and is also the unit used when calibrating salinometers.
2: PSU/PSS (Practical salinity units): Practical Salinity Scale, which is almost identical to ppt in practice.
3: S.G. (20/20) (specific gravity): relative density, that is, specific gravity.
Operation point: need standard salinity liquid to calibrate
Note: To ensure that the 35.00ppt calibration liquid is calibrated at a temperature of 25°C
The higher the temperature, the more the liquid expands and the lower the salinity, and vice versa.
Correct procedure:
Throw a packet of standard liquid into the vat, take it out after 10 minutes and dry it with paper.
Tear off half or the top ¼ of the bag and insert the salinometer.
Squeeze the bag with one hand, dip the bottom ¼ of the bag into the tank water to maintain 25°C-26°C. When the temperature on the top of the salinometer is unchanged at around 25°C, press Cal with the other hand to carry out the calibration operation.
Salinity Range : 0.00-10.00ppt
Salinity Resolution : 0.01ppt
Salinity Accuracy : ±1%F.S.
Salinity Range : 0.00~42.00psu; 0.00~ 80.00ppt
Salinity Resolution : 0.01
Salinity Accuracy : ±1% F.S.
Salinity Range : 0.00~80.00ppt, 0.00~42.00psu, 0.00~8.00%
Salinity Resolution : 0.01,0.1,1
Salinity Accuracy : ±1% F.S.
An optical salinometer uses the light refraction principle, which, according to different concentrations of different liquid components, has a different refractive index of the salinity determination principle.
Simple operation, just the solution to be measured evenly covered in the prism to ensure that the temperature of the solution and the prism temperature are consistent through the photoelectric conversion or visual method to read out the salinity.
Operation points:
Don't touch the metal part in front when measuring.
Different room temperatures, the 0 point line will have different positions; the higher the room temperature, the lower the 0 line, the lower the room temperature, the higher the 0 line. Before each use, please use RO water to correct the zero. Also don't immerse the metal head in tank water to get the salinity meter to the same temperature (unless the zeroing is also immersed in 25°C RO water). Room temperature calibration is fine.
Tool | Results | Principle | Operation |
---|---|---|---|
Salinity Meter | Salinity and Specific Gravity | Uses the principle of electrical conductivity to measure salinity by measuring conductivity in a body of water. | The probe is immersed in the liquid to be measured and read. |
Density Meter | Specific gravity | Archimedes' principle of determining density by buoyancy. | Place the densitometer in the water and read it after it has stabilised. |
Refractometer | Salinity and specific gravity | A refractometer measures the refractive index in a body of water and calculates salinity from the relationship between refractive index and salinity. | A sample drop is added to the lens and the cover plate is read. |
Overall, salinometers play an indispensable role in environmental monitoring, water resource management and scientific research. As technology advances and continues to innovate, the performance and accuracy of salinometers will continue to improve, contributing to a more complete understanding and protection of the health of our waters. In the future, as science and technology continue to evolve, salinometers will continue to play a key role in hydrological and ecological research, contributing to a deeper understanding of the Earth's water environment.