What Is a Salinometer?

Ray Hawk

A salinometer is a machine that is capable of measuring the table salt (NaCl) content, known as salinity, of a solution. Another name for a salinometer is a conductivity meter, as dissolved salt in water will increase its ability to conduct electricity at measurable levels. Equipment to measure the salt quantity of water is widely used on ships, so its fitting that the first apparatus to do this was invented by several oceanographers. The Wenner-Smith-Soule salinometer was built in 1930, and, in 1934, it was incorporated into International Ice Patrol Vessels. The International Ice Patrol (ICP) was established in 1914 after the sinking of the Titanic to monitor the movement of icebergs in the north Atlantic Ocean so that further ships collisions could be avoided.

Some of the most high tech salinometers in the world are used in desalination plants to ensure the water is safe for use.
Some of the most high tech salinometers in the world are used in desalination plants to ensure the water is safe for use.

The floatation of freshwater icebergs on the ocean surface is directly affected by its degree of salinity, but this is not the only use for a salinometer. They are also commonly used to measure the salt content of blood, since too much salt in the diet can lead to high blood pressure. The devices are also used on ships that have desalination equipment to purify salt out of water, such as on submarines and cruise ships. A salinometer measurement ensures that the final product of desalination is safe to drink.

A salinometer can measure the amount of table salt in a solution.
A salinometer can measure the amount of table salt in a solution.

The salt content of food can also be measured by a salinometer device through one of four methods. It may have a meter that measures chloride ions in the food and coverts that to a salt content measurement, or a meter to measure sodium ions and do the same. Another approach is to measure the electrical conductivity of the food and convert that to the level of salt present. Finally, a salinometer for measuring salt content in foods that are transparent can measure refractive light qualities by passing a low power laser beam through the food, and convert the readout to the salt quantity present.

Salinometers were originally fairly large, floor-mounted machines. In 1961, Bruce Hamon and Neil Brown, oceanographers in Australia's Commonwealth Science and Industrial Research Organization (CSIRO), developed a portable model that weighed only 33 pounds (15 kilograms). It replaced traditional oil-bath thermostats with a thermistor, which would alter electrical resistivity as temperature changes took place, and it had an accuracy level within 0.003%. Further refinements of the salinometer were done in 1975 by Tim Dauphinee of the National Council of Canada in Ottawa to create a laboratory model that is still widely used as of 2011.

A salinometer measures the amount of salt left after desalinating seawater.
A salinometer measures the amount of salt left after desalinating seawater.

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Discussion Comments


@indigomoth - Possibly they'd be able to simply test your sweat instead of your blood if necessary? I could see them doing this at a sporting event.

I know my sister competed in a Iron Man a few years ago and they told her that she had to make sure to keep her salt and electrolyte levels up.

She drank a bunch of sports drinks in order to be sure and was actually disappointed when they weighed her after the race (to check her fluids) and she had gained weight!

But since she wasn't showing any bad signs they didn't check her out further and she was fine.


@croydon: Yes, apparently cruise ships have been doing this for many years. The common method used is a multi-stage flash evaporator (MSF) and it equipment as of 2006 can process 100 to 1,000 metric tonnes a day of seawater into fresh water.

Desalination is an energy intensive process though, so it hasn't been practical everywhere, and has mostly been used in regions where there's abundant energy and little fresh water, such as in the Middle East. But the technology is becoming more practical. Desalination is done now in Saudi Arabia, Australia. Even the US base in Cuba at Guantanamo Bay has been able to desalinate up to 3.4 million gallons of water every day since Cuba cut off water supplies to the base back in the 1960s.


I never actually thought of the fact that they could use a measure to see how much salt was in a person's blood.

I know I must eat way too much salt, as I really like savory and salty foods, but I also do a lot of exercise and sweat a lot so I think it probably balances out.

I know I've been in a situation where it was hot enough that I was warned that my salts might get too low, and that I should make sure to eat enough just in case, so it's definitely possible to lower your salt through sweating.

I don't think they'd bother to check your blood with a salinometer to make sure you have enough salt though, as it would be easier to just give you a salt tablet or electrolytes and send you on your way.


I didn't realize that cruise ships use desalination equipment to purify water. That actually makes me feel better about using cruise ships, as people are always talking about how environmentally unfriendly they are. They do use an awful lot of food and I'm sure quite a bit of it goes to waste. But I always thought that the water they use came from fresh sources on land and was also wasted, for example in showers and things like that.

If it is processed through a miniature desalination plant and hopefully the waste water is properly processed as well then they aren't "wasting" the water found on land at least.

It makes sense though. It would be really difficult to store enough fresh water for all the people they have on board at any given time.

I imagine they have to make sure to keep the salinometer working at all times to make sure nothing is going wrong with the equipment though.

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