Sooo...i'm having some trouble here. I have about 3000 feet of plastic tubing (that looks a lot like the rubber tubing you'd see in a lab). Thats all i know about it.....and i need to find the right sized pump to get 2 gpm of water. Its 1/2 inch diameter tubing. Any sort of estimate would be nice.......trying to make sure i don't get a pump to weak. But don't wanna go to overboard (limited funds). thanks
I suppose that tubing will be used horizontal at all times during the course of operation with out any fittings. If yes then get pressure at the outlet end by Q (Flow)= Pressure x Area (inner) Find pressure drop from any sourse ( e.g. Ask manufacturer for pressure drop per 1000 foot) Add pressure drop of entire lenght to pressure from formula. Have 20% safety factor added. In case of any fittings used add pressure drop of fittings (from Mfg.) to pressure drop of tubing, if height changes; for every 2.31 feet have a loss of 1 PSI added to original loss of tubing before adding safety factor. Hope it help
Take a look at friction loss table on the Internet. I saw one table that said 1.55 psi per 100 feet, and another that said 3.8. In fire sprinkler work, we use tables derived from the Hazen-Williams formula. I don't have a table that goes that low on flow. A search for Hazen-Williams will get you to the formula. You will want to use the actual ID or the tube. It may be different from the nominal ID. For a roughness factor you could use 140.
