here it is.
In order to calculate pipe volumes the following formula can be used.
Pipe Volume = 0.7854 x D2 x L.
D. being diameter or the pipe L. being the length of the pipe.
To find the volume of 100mtrs of 15mm pipe you will do the following calculation.
Pipe Volume:- 0.7854 x 0.015 x 0.015 x 100 = 0.01767 M3 , to convert to Ltrs multiply by 1000
== 17.67 Ltrs.
hope this helps,cheers.