Picture a tank with fluid in it with a hole in the bottom. All the fluid could drain out of that hole.
Now instead of the hole, picture a pipe sticking up from the bottom of the tank half the height of the tank.
Only the top half of the fluid can drain through that pipe because when half the fluid is gone the top of that pipe is standing above the level of the fluid.
This is a stand pipe. It is used to limit or prioritise fluid levels.
Last edited by FE Hoppy; 28th September 2010 at 11:58.