Moisture in Propane Liquid

Greetings to all


We normally recieve propane in trucks but it does have some moisture.

How can I find:

1. The saturation temperature of moisure (water) in Propane liquid? can I use The Psychrometric chart?

2. Henry's law constant for water?

Thanks

Refrigeration grade propane doesn't have any appreciable water content.

Low grade propane may do though. You could send a sample for analysis, or a simple field test is called the valve freeze test, where you discharge some propane through a valve and time how long it takes to freeze up, the wetter it is the quicker it will freeze. This would be an IP/ASTM type of test, obviously you need the right type of valve etc., but it will all be in the relevant standard. It's not very accurate but it's the easiest.

Just looked it up, see ASTM D2713-91 (2001) for details.

It does have ppm level of moisture.

I have a section of an article someone gave me - no idea where from though:

Temperature ppm saturated level in liquid propane
-40C 3ppm
-30 5
-15 13
+6C 44
+15 75
+30 173
+45 360

Note that for low temps (below zero) the vapour holds about 20 times more moisture than liquid, this is about 10 times around ambient temperature. I also have some data from GE Sensing which shows higher saturation levels (liquids) - note sure which is more accurate.

Hope this helps