What does one need to consider when using a wet seal legs? When to choose glycol, diesel, flushing oil, kerosene, process etc. I'm aware each has its own specific gravity but why choose diesel instead of kerosene as an example.
I saw many applications using glycol, but if I were you the electronic remote sensor are the best solutions. You won't have problems with installation and everything related to this sort of application. If you want to use the wet seal leg, you need to pay attention to the molecular weight (MW) of the filled product should be higher than water, and the boiling point as well. Further, you need to check the viscosity in low temperature.
My suggestion is:
1 -Electronic remote sensor
2 -Diaphragm application
3 -Wet seal leg
You can find more information here > https://visaya.solutions/article/definitive-guide-pressure-transmitters/
On a quick reply off my head, you need to consider the following when selecting the wet seal leg fluid.
1. The 1st choice should be that the wet seal leg fluid and process fluid should be same. The reason you are choosing the wet seal leg is the condensation of the vapour. For example water for steam. Advantage is you don't have to check and fill (if necessary) the wet leg regularly. The condensation from vapour will keep it full always.
2. If same fluid is not possible the next choice will be fluid which will not mix with the process fluid.
3. Next point it should have higher density than the process fluid.
4. It should not vapourise easily at the temperature of your application.
5. It should not be frozen at minimum temperature of your application