I am currently working on a project for my home brewery using a V350-35-ta24.
In my boil kettle (15 gallons), I am using a fairly cheap direct screw in 4-20ma pressure sensor to calculate water volume using linearization to convert the value to gallons. This works well, until i start to heat the boil kettle. The pressure sensor value increases based on temperature increase, which will throw off other calculations i intend to implement down the road.
I have attached my project. If you look at the first net in the main routine I have compensated for this by adding a second linearization based on the difference in gallons between cold starting water temp and 200 degrees F, then subtracting this number from the original value to find actual volume. This is obviously not perfect, as i assume different volumes of water will have slightly different results, but was the best i could come up with to get things close. The volume is also used for safety checks, to make sure that the heating element contactor turns off when there is not enough water. So its important that its as accurate as possible
I am new to PLC programming. when you look at my project you may find things are not done perfectly, but everything is labeled well and currently working other than the volume is less accurate than i would like.
What is the best way to compensate for the temperature change to keep the volume measurement consistent?
Any advice would be greatly appreciated!
V350 Brewery.vlp