Combined Specific Gravity of a Mixture of Liquid and Gas

[Stressman76]

Hi, all. I am currently working on a problem where we have a flow in a line that is about 50% liquid and 50% gas. I know the specific gravity of the liquid, but always assume a specific gravity of 0 for the gas. How would I go about calculating the specific gravity of the combined contents of the line? Thanks in advance for the help!

 

[JStephen]

If it's 50/50 based on volume, you could just take 50% of the specific gravity of the liquid.
Flow could be highly erratic if you have low spots and high spots in the line. With uniform slope, you could have the vapor moving a lot faster than the liquid.
If you know exact composition and have design data for that product, it'd be easy enough to work out.
With water, use the steam charts, the steam "quality" is the critical number.
For design gravity loading, I would assume completely full of liquid.