judy1951 wrote:what is the formula for calculating liquid volume eg. I have a 7 inch diameter pipe with 1 foot of water inside. How do I calculate the amount of water in gallons?
If I understand you correctly you need to calculate volume of a cylinder. It is equal to height * pi * radius squared.
In your case it is going to be (all figures in inches): 3.5*3.5*3.14*12 = 461.6 cubic inches. Here 3.5 inches is the radius (half of the diameter). 3.14 is pi number, 12 inches is the length (or height). 461.6 cubic inches equal to 2 gallons (see
volume conversion page)
So the amount of water in your pipe is about 2 gallons.