I'm taking a pipe fitting class and I can not find witch valve had the most restriction.
VALVES CAUSING RESTRICTIONS? WTF? When they are CLOSED or not open all they way, they can cause a restriction. Otherwise, in and of themselves... valves do not cause restrictions.
Any valve that because of its design involves a change of direction of the medium it is carrying has a definate restriction and a globe valve is a good example of this as the valve has around a 90 degree change of direction in its operating method.A straight through type valve such as a gate or ball valve especially the latter offer some resistance but if required what is called a full bore valve may be used where the operating throat is increased such that it is no smaller than the pipework it is connected to.
A globe valve has a lot of resistance (restriction) even when it is open A metering valve has adjustable restriction but i am thinking that that is not what you are asking.... A gate valve or ball valve has less resistance (a ball valve has almost none).
