How many litres does a 4ft x 3ft pipe hold?

To calculate the volume of a cylindrical pipe, you can use the formula ( V = \pi r^2 h ). For a pipe with a diameter of 4 ft (radius of 2 ft) and a length of 3 ft, the volume is approximately ( V = \pi (2^2)(3) \approx 37.7 ) cubic feet. Since there are about 7.48 gallons in a cubic foot and 1 gallon is approximately 3.785 liters, the pipe holds about 142.3 liters.