OK, here we go : I will try and make this sound far more complicated than it really is
The information you need to work out the volume of liquid in your tank is :
1) The Radius of the cylinder ( Half the diameter
)
2) The Width of the cylinder ( or Length if you prefer )
3) The depth of the water in it
Assume the tank is less than half full :
Looking end on the shape formed by the water is a "Segment" as represented by the green area :
The depth of water is the height of the segment represented by Line E-D ( also known as the "Sagitta" ) so you need to make up a dipstick or other method of measuring the depth of water left in the tank.
Go to this web site :
Daysleeper's Tank Calculator
Check the option for knowing the Radius and Segment Height, fill in the details and click "Calculate" All you need to do then is multiply the answer by the Width ( or Length ) of the tank and you have the volume of water in it.
If the tank is more than half full ( a bit like my Glass
) then work out the total volume of the tank using
"PI x R squared x Width ( or Length )" and halve the answer. ( To get the volume of the bottom half of the tank.
Then perform the segment calculation for the top half of the tank - remembering this time that when you dip the tank, the dry bit will be the segment height ! You need to calculate the dry segment area and subtract it from the volume of a half full tank, then add it it to the bottom half of the tank and multiply it by the Width ( or Length ) to get the total volume.
( Or better still wait until the tank is less than half full
)
After a few calculations at various depths you can mark your dipstick ( If you'll excuse the phrase ) and you're done
Coconutty
Edited to sort the typo's and to add :
- I think I might know him
