absolute newb ?: what is NPT?
 

sorry if this is completely dumb...
but i have seen fittings referred to as 1/2x3/8NPT, or something similar. i have yet to find out what the NPT measurement means. if someone could help me that would be great...


thanks a lot.

NPT = National Pipe Thread

It the U.S. standard for Pipe threads NOT bolt threads, Most pipe or barb fittings are NPT, be careful though some blocks use BSSP ( British standard ) also there is NPTF ( National pipe thread FINE )
BSSP is close to NPT and with a bit of force NTP fittings will work ( I know I have NPT fittings in both my Innovatek blocks and they come threaded BSSP.
Hope this helps
Aardil

NPT stands for National Pipe Thread. The way it works is this. Say you have a barb that is 1/2"x1/4"NPT the 1/2" designation is for the OD of the barb so it will take a 1/2" ID tube. Now the 1/4" NPT would be the inside diameter of the pipe, sender, or threaded end of the barb. So if you have a 1/4"-18 NPT the actual outside diameter of the pipe would be 35/64". Follow this link for a chart on other NPT sizes as well. As for the the -18 after the NPT size would indicate threads per inch. Now remember if you tap a 1/4" NPT hole you'll need a 1/4" MPT barb. NPT is the umbrella term for national pipe thread, MPT is male pipe thread , and FPT is female pipe thread.

If you're still confused, check McMaster.com. They explain pipe fittings in detail at the frnt of their cataloge (electronic and print).

ok thanks a lot.
so basically npt is like the ID of the barb?
(maybe im still not getting it)
ill check that site.

NPT is the size of the threading that the back end of the barb would screw into.

Check http://www.mcmaster.com/catalog/108/html/0002.html
and
http://www.mcmaster.com/catalog/108/html/0003.html