Hey, I am in the process of trying to build a design to measure the specific gravity of a liquid (usually around 65deg C) through a straight pipe between 2 tanks.
My thought process was to get a flow meter sensor to measure the mass or volumetric flow through the pipe. Then if I know the area volume of the straight pipe section I should be able to find the density of the liquid, thus finding the specific gravity.
I am unsure if this is the best way to handle this issue, or is there another way I should look into? If it is, anyone have any good flow meter sensor recommendations?
A flow meter cannot measure the mass of the liquid flowing through the pipe, only it's volume. You need to know both mass and volume to measure it's "specific gravity" which is an old name for "density". Specifically, it is density relative to to pure water.
Accurately measuring volume using a flow meter could be difficult, I think. It might be easier to accurately measure the mass of a known volume of the liquid.
Do you need to measure the actual value of the specific gravity, or only sense whether it is above or below a threshold?
The principle goes back a few decades so I expect that there are quite a few designs available though they could be quite expensive. Once you know the mass of fluid flowing you can calculate its density knowing the pipe volume.
This design is for beer making process and once the liquid flows through the straight pipe section connecting the 2 tanks is where I would require to calculate the density.
The specific value of the density must be calculated and then shown on a LCD screen
The liquid is wort in the beer fabrication process it is a straight pipe travelling through 2 tanks so not too sure how I’d be able to effectively weigh the pipe connected/mounted to the 2 tanks
They’d like to know the density (to get specific gravity) so they can accurately batch and ferment their beer
Yes, I think you have understood the problem. You need both weight/mass and volume in order to calculate density. You can measure the volume of liquid flowing through a pipe with a flow meter, but measuring the mass of that liquid is not easy to do.
You also need to measure the volume and mass very accurately in order to calculate the density accurately enough to know the specific gravity, because I think the differences in density will be very small in practice.
In short, a sealed cylinder floats on the surface of the liquid, but it does not float perfectly upright. It tilts at an angle and that angle depends on the density of the liquid. Using an accelerometer, the MCU sealed inside in the cylinder can measure the angle of tilt and calculate the density from that. It then transmitts the density figure over wi-fi to be logged in a database.