absolute newb ?: what is NPT?

m3_arun · 12-17-2002, 10:04 PM

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.

Aardil · 12-17-2002, 10:25 PM

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

FRAGN'STIEN · 12-17-2002, 10:31 PM

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.

redleader · 12-18-2002, 12:49 AM

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

m3_arun · 12-18-2002, 10:42 AM

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

redleader · 12-18-2002, 01:13 PM

Quote:

so basically npt is like the ID of the barb?

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

12-17-2002, 10:04 PM	#1
m3_arun Cooling Neophyte Join Date: Oct 2002 Location: san jose, ca Posts: 91	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.

12-17-2002, 10:31 PM	#3
FRAGN'STIEN Cooling Savant Join Date: May 2002 Location: Rathdrum, ID Posts: 380	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. __________________ This space for rent Last edited by FRAGN'STIEN; 12-17-2002 at 10:37 PM.

12-17-2002, 10:25 PM	#2
Aardil Cooling Savant Join Date: Oct 2002 Location: Louisiana Posts: 174	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

12-18-2002, 12:49 AM	#4
redleader Thermophile Join Date: Jun 2001 Location: The deserts of Tucson, Az Posts: 1,264	If you're still confused, check McMaster.com. They explain pipe fittings in detail at the frnt of their cataloge (electronic and print).

12-18-2002, 10:42 AM	#5
m3_arun Cooling Neophyte Join Date: Oct 2002 Location: san jose, ca Posts: 91	ok thanks a lot. so basically npt is like the ID of the barb? (maybe im still not getting it) ill check that site.

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