24 Inch Length 1.5 Inch NPT Pipe Extension

hey Gil here today we're going to talk about pipe sizes NPT national pipe spread and we're going to explain a little bit about how you measure it and how you get it right the first time one of the first things you need to understand about NPT sizes is why is a pipe that measures one inch on the outside called a three-quarter inch NPT the reason for it is because the three-quarter inch stands for the inside diameter of the pipe where the water the air would flow of course you've got the outside diameter the thickness of the pipe wall and it adds about a quarter of an inch sixteenth of an inch on either side so it ends up measuring one inch for three-quarter inch NPT but 3/4 inch is the inside where the flow is actually happening and that's the reason that it's so confusing now this is a check valve but I'm just using this check valve to show pipe thread when you have a female pipe thread