Re: Please explain NPT fittings??
[Re: GO_Fish]
#72542
06/12/08 09:59 PM
06/12/08 09:59 PM
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Joined: Jul 2003
Posts: 6,167 Maryland
GO_Fish
OP
master
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OP
master
Joined: Jul 2003
Posts: 6,167
Maryland
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Thanks guys! I bought my pump from Mancini, and their site does not give all the info that the Summit site does. The directions that came with the pump specifically say not to use teflon tape, it will break the fitting. I guess it is too slick and results in over torque? Anywho, I can now order my 1/4 npt fittings with 5/16" barb.
Scott B.
"I'm a self-made man... I started with nothing, and I still have most of it!"
68 360 rusty B'cuda 'vert (GO Fish)13.59@ 98.72 mph
69 340 GTS stock 14.18@ 95.60 mph
01 5.9L Ram 1500 Quad Cab 4x4
01 3.5L 300M 16.23@ 86.97 mph
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Re: Please explain NPT fittings??
[Re: GO_Fish]
#72543
06/12/08 10:16 PM
06/12/08 10:16 PM
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Joined: Apr 2008
Posts: 1,195 Snowing in the north!
Dart 340
moparts member
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moparts member
Joined: Apr 2008
Posts: 1,195
Snowing in the north!
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Quote:
Thanks guys! I bought my pump from Mancini, and their site does not give all the info that the Summit site does. The directions that came with the pump specifically say not to use teflon tape, it will break the fitting. I guess it is too slick and results in over torque? Anywho, I can now order my 1/4 npt fittings with 5/16" barb.
They are a nice pump, I just put one in my dart. Do not use teflon tape. I think the threads are NPTF on the pump side. Tape will crack the housing. You can get the fittings pretty much any hardware store if you want brass. If you want cool blue anodized PM me and I'll send you some.
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Re: Please explain NPT fittings??
[Re: GoodysGotaCuda]
#72545
06/12/08 10:45 PM
06/12/08 10:45 PM
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Joined: Apr 2008
Posts: 1,195 Snowing in the north!
Dart 340
moparts member
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moparts member
Joined: Apr 2008
Posts: 1,195
Snowing in the north!
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Quote:
Interesting, i got my pump used when i ran the carter pump. So nothing told me to not use teflon tape, it ran just fine for a daily driven year with the teflon tape. I still have the 'good used' carter pump in my boxes. I run teflon tape on the NPT fittings at my fuel pressure regulator, holley blue pump and fuel filter. No issues in 3 years there.
Mine said not to use it. I think the reason it that they are nptf (fuel) threads. One is straight and one is tapered so they self seal. If it's working well, dont mess with it.
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Re: Please explain NPT fittings??
[Re: GoodysGotaCuda]
#72546
06/12/08 10:48 PM
06/12/08 10:48 PM
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Joined: Oct 2006
Posts: 4,765
quick77rt
Parts Problem
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Parts Problem
Joined: Oct 2006
Posts: 4,765
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I went through this when I was very young and it is confusing. Here is the same as below but the website which is easier to figure out. Its two different worlds...I hope this helps. http://www.plumbingstore.com/pipethreadsizing.htmlDefinition of pipe thread acronyms NPT National Pipe Thread FPT Female Pipe Thread MPT Male Pipe Thread PTF SAE short tape pipe thread NPTF American National taper pipe thread for dryseal pressure-tight joints NPSM American National straight pipe thread for mechanical joints NPSI American National straight intermediate pipe thread Male threads: Measure the outside diameter of the large portion of the thread at "A"; Find figure nearest this dimension in column 1 or 2 of chart. The dimension in column 3 will be your nominal pipe thread size. Female Threads: Measure top diameter of thread at "B"; Find figure nearest this dimension in column 1 or 2 of chart. The dimension in column 3 will be your nominal pipe thread size. Column 1 Column 2 Column 3 Column 4 Column 5 OD Fraction Inch (for quick reference only) Actual (decimal) Inch. Pipe Thread Size Normal engagement for tight joint (dimension "C") Threads per Inch 5/16 0.3125 1/16 0.2611 27 13/32 0.405 1/8 0.2639 27 35/64 0.540 1/4 0.4018 18 43/64 0.675 3/8 0.4078 18 27/32 0.840 1/2 0.5337 14 1-3/64 1.050 3/4 0.5457 14 1-5/16 1.315 1 0.6828 11-1/2 1-21/32 1.660 1-1/4 0.7068 11-1/2 1-29/32 1.900 1-1/2 0.7235 11-1/2 2-3/8 2.375 2 0.7565 11-1/2 2-7/8 2.875 2-1/2 1.1375 8 3-1/2 3.5 3 1.2000 8 4 4.0 3-1/2 1.2500 8 4-1/2 4.5 4 1.3000 8 Two common pipe thread sizes exist, the tapered National Pipe Thread (NPT) and the straight National Standard Free-Fitting Straight Mechanical Pipe Thread (NPSM). The tapered threads are for joining and sealing, the straight threads are only for joining. The Dry-seal thread (NPTF) allows for joining without sealants. Three less common threads exist, the Garden Hose Thread (GHT), Fire Hose Coupling (NST) and British Standard Taper Pipe Thread (BSPT). The NPT and NPTF threads are interchangeable with sealants such as PTFE tape. None of the other thread standards are interchangeable. Female NPT threads can be designated as "FPT" and male NPT threads can be designated as "MPT." Pipe sizes do not refer to any physical dimensions. The outside diameter of each pipe or fitting must be measured and compared to the table for size identification. For example, a 3/4" NPT pipe thread has an outside diameter of 1.050 inches. Each thread size has a defined number of threads per inch (TPI). The 3/4" NPT pipe thread has 14 threads per inch. Both the TPI and OD of the thread are required for positive identification of thread size because several sizes have the same TPI.
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Re: Please explain NPT fittings??
[Re: quick77rt ]
#72548
06/12/08 11:27 PM
06/12/08 11:27 PM
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Joined: Apr 2008
Posts: 1,195 Snowing in the north!
Dart 340
moparts member
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moparts member
Joined: Apr 2008
Posts: 1,195
Snowing in the north!
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Quote:
I went through this when I was very young and it is confusing.
Here is the same as below but the website which is easier to figure out.
Its two different worlds...I hope this helps.
http://www.plumbingstore.com/pipethreadsizing.html
Definition of pipe thread acronyms NPT National Pipe Thread FPT Female Pipe Thread MPT Male Pipe Thread PTF SAE short tape pipe thread NPTF American National taper pipe thread for dryseal pressure-tight joints NPSM American National straight pipe thread for mechanical joints NPSI American National straight intermediate pipe thread
Male threads: Measure the outside diameter of the large portion of the thread at "A"; Find figure nearest this dimension in column 1 or 2 of chart. The dimension in column 3 will be your nominal pipe thread size. Female Threads: Measure top diameter of thread at "B"; Find figure nearest this dimension in column 1 or 2 of chart. The dimension in column 3 will be your nominal pipe thread size. Column 1 Column 2 Column 3 Column 4 Column 5 OD Fraction Inch (for quick reference only) Actual (decimal) Inch. Pipe Thread Size Normal engagement for tight joint (dimension "C") Threads per Inch 5/16 0.3125 1/16 0.2611 27 13/32 0.405 1/8 0.2639 27 35/64 0.540 1/4 0.4018 18 43/64 0.675 3/8 0.4078 18 27/32 0.840 1/2 0.5337 14 1-3/64 1.050 3/4 0.5457 14 1-5/16 1.315 1 0.6828 11-1/2 1-21/32 1.660 1-1/4 0.7068 11-1/2 1-29/32 1.900 1-1/2 0.7235 11-1/2 2-3/8 2.375 2 0.7565 11-1/2 2-7/8 2.875 2-1/2 1.1375 8 3-1/2 3.5 3 1.2000 8 4 4.0 3-1/2 1.2500 8 4-1/2 4.5 4 1.3000 8 Two common pipe thread sizes exist, the tapered National Pipe Thread (NPT) and the straight National Standard Free-Fitting Straight Mechanical Pipe Thread (NPSM). The tapered threads are for joining and sealing, the straight threads are only for joining. The Dry-seal thread (NPTF) allows for joining without sealants. Three less common threads exist, the Garden Hose Thread (GHT), Fire Hose Coupling (NST) and British Standard Taper Pipe Thread (BSPT). The NPT and NPTF threads are interchangeable with sealants such as PTFE tape. None of the other thread standards are interchangeable. Female NPT threads can be designated as "FPT" and male NPT threads can be designated as "MPT."
Pipe sizes do not refer to any physical dimensions. The outside diameter of each pipe or fitting must be measured and compared to the table for size identification. For example, a 3/4" NPT pipe thread has an outside diameter of 1.050 inches. Each thread size has a defined number of threads per inch (TPI). The 3/4" NPT pipe thread has 14 threads per inch. Both the TPI and OD of the thread are required for positive identification of thread size because several sizes have the same TPI.
thats absolutely awesome! you spent way more time explaining this and I would have. Two thumbs up.
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Re: Please explain NPT fittings??
[Re: 6PakBee]
#72549
06/13/08 12:01 AM
06/13/08 12:01 AM
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Joined: Jan 2003
Posts: 8,089 Sorrento, BC, Canada
4speeds4me
master
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master
Joined: Jan 2003
Posts: 8,089
Sorrento, BC, Canada
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Quote:
Quote:
Quote:
Interesting, i got my pump used when i ran the carter pump. So nothing told me to not use teflon tape, it ran just fine for a daily driven year with the teflon tape. I still have the 'good used' carter pump in my boxes. I run teflon tape on the NPT fittings at my fuel pressure regulator, holley blue pump and fuel filter. No issues in 3 years there.
Mine said not to use it. I think the reason it that they are nptf (fuel) threads. One is straight and one is tapered so they self seal. If it's working well, dont mess with it.
I would guess that the Teflon tape "lubricates" the threads to the point that the fitting can be easily overtorqued and crack the female fitting (housing).
I doubt that overtorquing or cracking is the issue with Teflon. I would suspect that it is MUCH more likely that ordinary teflon tends to break down when exposed to petroleum products. Anytime I have to deal with a fitting that's going to have any kind of petroleum product, liquid or vapor, I need to use a thread sealant (liquid or tape) that is rated accordingly. Nothing worse than a fire because a leak generated from sealant breaking down...or winding up with the junk in your carb or injectors...
2 Demons...no, not my kids!
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Re: Please explain NPT fittings??
[Re: 6PakBee]
#72551
06/13/08 08:38 AM
06/13/08 08:38 AM
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Joined: Feb 2005
Posts: 28,312 Cincinnati, Ohio
Challenger 1
Too Many Posts
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Too Many Posts
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
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Quote:
Quote:
I doubt that overtorquing or cracking is the issue with Teflon. I would suspect that it is MUCH more likely that ordinary teflon tends to break down when exposed to petroleum products. Anytime I have to deal with a fitting that's going to have any kind of petroleum product, liquid or vapor, I need to use a thread sealant (liquid or tape) that is rated accordingly. Nothing worse than a fire because a leak generated from sealant breaking down...or winding up with the junk in your carb or injectors...
I assumed (there's that word again!) that we were talking about the applicable Teflon sealing tape, not something you'd pick up at Home Depot. If you do a web search there are Teflon tapes formulated for fuel usage. Is it still a good idea? I don't know. I'm not a personal fan of tape. The tape gives you a false indication of how tight the fitting is. I've personally cracked fittings and some of my friends have, primarily in castings, from overtorquing the fitting. I like something like Loctite 567, a gasoline rated anaerobic sealant. But whatever floats your boat.
I'm a fuel dealer, when I get new fuel nozzles in the box the directions say Not to use teflon tape. The tape acts like a wick and causes the fitting to weep. Ever notice how the tape turns yellow after some use? Plus as we all know, if it is applied wrong it can get in places you don't want it.
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Re: Please explain NPT fittings??
[Re: Dennis_K]
#72553
06/13/08 04:56 PM
06/13/08 04:56 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,376
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Nice brass fittings at Ace Hardware. R. I have used teflon tape with success. Try to keep the bits of tape out of the inside of the fitting, they have been known to plug small openings. I have also used Fel-Pro TIGHT which is a teflon-bearing liquid sealant. It's not that complicated!
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Re: Please explain NPT fittings??
[Re: Pacnorthcuda]
#72554
06/13/08 08:56 PM
06/13/08 08:56 PM
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Joined: Oct 2005
Posts: 8,914 Ontario, Canada
Stanton
Don't question me!
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Don't question me!
Joined: Oct 2005
Posts: 8,914
Ontario, Canada
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Quote:
self tighting.
Well this got me curious 'cuz I'd always tightened 'em myself so I laid a fittin' on the bench next to a pump I had lyin' aroun' and went in an' had my supper an' when I went back out to the shop they wuz in the same place I left 'em. So I got t' thinkin' maybe I got the self-sealing kind an' not the self tightenin' kind !!!
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