Not exactly irrigation related, but similar. Looking for equation or information on: What is the effect of a restriction on flow? If you have a 1" pipe (nom. size, your choice of mtl.), certain pressure, etc. and you have a fitting that has a slightly smaller ID, what will the effect be on flow (volume) after that fitting/restriction? Reason I am asking, and you can dice me if you wish, is that I am working on a project (not irrigation related .... medical related ..... think hypodermic needles) so it's super small volume and very minute, if any, flow difference. Not sure where to look on the web, but figured some of you may have an idea or two. Thanks a bunch!