1/4" BSP to 1/4" NPT

**RichClark** · 7th July 2008, 12:57

Hi,

I'm not sure of the best place to post this question, but i figured the homebuilders would be likely candidates to know.

I need to covert from 1/4" BSP to 1/4" NPT, so I guess i need 1/4 BSP male to 1/4 NTP female.Does anyone know where i could source these from? (UK Preferably) I want to use these on my booster to add some QC's that I bought from Golem Gear so I guess the adaptor needs to be rated for high pressure.

Thanks

Rich

louisrankin · 7th July 2008, 13:15

Rich,

Is this what you need?

HP fitting stainless 316 NPT BSP 1/4 oxygen gas booster on eBay, also, Other SCUBA, SCUBA Snorkelling, Sporting Goods (end time 25-Jul-08 13:07:59 BST)

Sorry just read the post you need male to female try Undersea Ltd - Serving the diving industry since 1970

I think they are the ones I had to buy for my Jetsam baby booster.

Louis

**rigdiver** · 7th July 2008, 13:19

Sub_Aqua Products in the UK
or contact iain-hsm on this board.
Undersea Ltd 202 82 20 25

**Dave Sutton** · 7th July 2008, 14:50

If all else fails, McMaster-Carr has them in both brass and stainless.

Dave

.

LukeN · 8th July 2008, 09:09

Or just go out and buy the tap? I think it is only about a 5 degree change of pitch.

Lancer4545 · 8th July 2008, 09:30

Quote: (Originally Posted by RichClark)

Hi,

I'm not sure of the best place to post this question, but i figured the homebuilders would be likely candidates to know.

I need to covert from 1/4" BSP to 1/4" NPT, so I guess i need 1/4 BSP male to 1/4 NTP female.Does anyone know where i could source these from? (UK Preferably) I want to use these on my booster to add some QC's that I bought from Golem Gear so I guess the adaptor needs to be rated for high pressure.

Thanks

Rich

Hey Rich,

There is such a minute difference in the threads it's quite acceptable to run an NPT tap through and "Modify" the existing thread and a whole lot easier. Just remember to get a "Tapered" tap and not a paralell one.

Regards,

lance

**RichClark** · 8th July 2008, 10:51

Quote: (Originally Posted by LukeN)

Or just go out and buy the tap? I think it is only about a 5 degree change of pitch.

Quote: (Originally Posted by Lancer4545)

Hey Rich,

There is such a minute difference in the threads it's quite acceptable to run an NPT tap through and "Modify" the existing thread and a whole lot easier. Just remember to get a "Tapered" tap and not a paralell one.

Regards,

lance

Cheers Guys, that might be the best option. So bleedin' obviously as well!

Woz · 10th July 2008, 16:26

You can screw BSP and NPT into each other up to 1/4". After that they won't fit. We used to screw them in all the time hydrotesting to pressures well in excess of 450 bar.

**RichClark** · 10th July 2008, 19:22

Quote: (Originally Posted by Woz)

You can screw BSP and NPT into each other up to 1/4". After that they won't fit. We used to screw them in all the time hydrotesting to pressures well in excess of 450 bar.

I could only get a few threads worth and didn't feel comfortable doing that as it HP O2 on my booster

iain-hsm · 10th July 2008, 20:13

I feel one of those “How many divers does it take to screw in a lightbulb” posts coming on.
You are all very naughty boys, ¼ NPT is not ¼ BSPT and I would like to know what you do with the left over half thread, that ends up spare?

1/4 NPT if you bother to look it up has 18 threads per inch and 1/4 BSP taper has 19

NPT - American Standard Pipe Thread Taper
Pipe Size (inches) Threads per Inch TPI - pitch Nominel Outside Diameter OD (inches)
1/16" 27 0.313"
1/8" 27 0.405"
1/4" 18 0.540"
3/8" 18 0.675"
1/2" 14 0.840"
3/4" 14 1.050"
1" 11-1/2 1.315"
1-1/4" 11-1/2 1.660"
1-1/2" 11-1/2 1.900"
2" 11-1/2 2.375"

BSP Taper
Nominal Size (inches) T P I Major Diameter (inches)
1/8" 28 0.383
1/4" 19 0.518
3/8" 19 0.656
1/2" 14 0.825
5/8" 14 0.902
3/4" 14 1.041
7/8" 14 1.189
1" 11 1.309
1-1/4" 11 1.650
1-1/2" 11 1.882
1-3/4" 11 2.116
2" 11 2.347

So anyone else talking crap about bolloking up perfectly good threads in sheer ignorance would be better off placing the method of thread "mixing" under the term: butchery. LOL
Kind regards Iain Middlebrook

7th July 2008, 12:57	#1 (permalink)
RichClark Classic KISS No. 226 Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Mar 2005 Location: Hove, UK Posts: 793	1/4" BSP to 1/4" NPT Hi, I'm not sure of the best place to post this question, but i figured the homebuilders would be likely candidates to know. I need to covert from 1/4" BSP to 1/4" NPT, so I guess i need 1/4 BSP male to 1/4 NTP female.Does anyone know where i could source these from? (UK Preferably) I want to use these on my booster to add some QC's that I bought from Golem Gear so I guess the adaptor needs to be rated for high pressure. Thanks Rich __________________ The more I learn about women, the more I want to go diving... just don't tell my wife I said that To taste something a little different, try http://www.thechillikitchen.co.uk
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7th July 2008, 13:15	#2 (permalink)
louisrankin Póg mo thóin Current Rebreather/s: Megalodon Other Rebreather/s: Sport Kiss Classic Kiss Join Date: May 2005 Location: Cambridge Posts: 315	Re: 1/4" BSP to 1/4" NPT Rich, Is this what you need? HP fitting stainless 316 NPT BSP 1/4 oxygen gas booster on eBay, also, Other SCUBA, SCUBA Snorkelling, Sporting Goods (end time 25-Jul-08 13:07:59 BST) Sorry just read the post you need male to female try Undersea Ltd - Serving the diving industry since 1970 I think they are the ones I had to buy for my Jetsam baby booster. Louis
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7th July 2008, 13:19	#3 (permalink)
rigdiver LEARNING CONTINUALLY Current Rebreather/s: Inspiration Vision Other Rebreather/s: Inspiration Classic Megalodon Join Date: Mar 2005 Location: TEXAS Posts: 427	Re: 1/4" BSP to 1/4" NPT Sub_Aqua Products in the UK or contact iain-hsm on this board. Undersea Ltd 202 82 20 25
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7th July 2008, 14:50	#4 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Evolution Megalodon rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,907	Re: 1/4" BSP to 1/4" NPT If all else fails, McMaster-Carr has them in both brass and stainless. Dave . __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com
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8th July 2008, 09:09	#5 (permalink)
LukeN New Member Current Rebreather/s: Optima Other Rebreather/s: Not Bought Yet Prism Topaz Join Date: Jun 2005 Location: Australia,West Aus Posts: 86	Re: 1/4" BSP to 1/4" NPT Or just go out and buy the tap? I think it is only about a 5 degree change of pitch. __________________ Luke Nelson www.imagedive.com.au
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8th July 2008, 09:30	#6 (permalink)
Lancer4545 RBW Member Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Jun 2007 Location: Cairns QLD Australia Posts: 746	Re: 1/4" BSP to 1/4" NPT Quote: (Originally Posted by RichClark) Hi, I'm not sure of the best place to post this question, but i figured the homebuilders would be likely candidates to know. I need to covert from 1/4" BSP to 1/4" NPT, so I guess i need 1/4 BSP male to 1/4 NTP female.Does anyone know where i could source these from? (UK Preferably) I want to use these on my booster to add some QC's that I bought from Golem Gear so I guess the adaptor needs to be rated for high pressure. Thanks Rich Hey Rich, There is such a minute difference in the threads it's quite acceptable to run an NPT tap through and "Modify" the existing thread and a whole lot easier. Just remember to get a "Tapered" tap and not a paralell one. Regards, lance __________________ You can run but you can't hide! ISC Appointed Megalodon Dealer for East Australia http://www.closedcircuitdivers.com.au info@closedcircuitdivers.com.au
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8th July 2008, 10:51	#7 (permalink)
RichClark Classic KISS No. 226 Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Mar 2005 Location: Hove, UK Posts: 793	Re: 1/4" BSP to 1/4" NPT Quote: (Originally Posted by LukeN) Or just go out and buy the tap? I think it is only about a 5 degree change of pitch. Quote: (Originally Posted by Lancer4545) Hey Rich, There is such a minute difference in the threads it's quite acceptable to run an NPT tap through and "Modify" the existing thread and a whole lot easier. Just remember to get a "Tapered" tap and not a paralell one. Regards, lance Cheers Guys, that might be the best option. So bleedin' obviously as well! __________________ The more I learn about women, the more I want to go diving... just don't tell my wife I said that To taste something a little different, try http://www.thechillikitchen.co.uk
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10th July 2008, 16:26	#8 (permalink)
Woz Custom Title Allowed! Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Jun 2005 Location: Nottingham Posts: 186	Re: 1/4" BSP to 1/4" NPT You can screw BSP and NPT into each other up to 1/4". After that they won't fit. We used to screw them in all the time hydrotesting to pressures well in excess of 450 bar. __________________ Still punting shiny diving tatt to gullible divers www.kitfondle.co.uk
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10th July 2008, 19:22	#9 (permalink)
RichClark Classic KISS No. 226 Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Mar 2005 Location: Hove, UK Posts: 793	Re: 1/4" BSP to 1/4" NPT Quote: (Originally Posted by Woz) You can screw BSP and NPT into each other up to 1/4". After that they won't fit. We used to screw them in all the time hydrotesting to pressures well in excess of 450 bar. I could only get a few threads worth and didn't feel comfortable doing that as it HP O2 on my booster __________________ The more I learn about women, the more I want to go diving... just don't tell my wife I said that To taste something a little different, try http://www.thechillikitchen.co.uk
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10th July 2008, 20:13	#10 (permalink)
iain-hsm Custom Title Allowed! Current Rebreather/s: MK 15.X Other CCR Other SCR Other Rebreather/s: Other CCR Other SCR Join Date: Mar 2005 Location: Loughborough England uk Posts: 347	Re: 1/4" BSP to 1/4" NPT I feel one of those “How many divers does it take to screw in a lightbulb” posts coming on. You are all very naughty boys, ¼ NPT is not ¼ BSPT and I would like to know what you do with the left over half thread, that ends up spare? 1/4 NPT if you bother to look it up has 18 threads per inch and 1/4 BSP taper has 19 NPT - American Standard Pipe Thread Taper Pipe Size (inches) Threads per Inch TPI - pitch Nominel Outside Diameter OD (inches) 1/16" 27 0.313" 1/8" 27 0.405" 1/4" 18 0.540" 3/8" 18 0.675" 1/2" 14 0.840" 3/4" 14 1.050" 1" 11-1/2 1.315" 1-1/4" 11-1/2 1.660" 1-1/2" 11-1/2 1.900" 2" 11-1/2 2.375" BSP Taper Nominal Size (inches) T P I Major Diameter (inches) 1/8" 28 0.383 1/4" 19 0.518 3/8" 19 0.656 1/2" 14 0.825 5/8" 14 0.902 3/4" 14 1.041 7/8" 14 1.189 1" 11 1.309 1-1/4" 11 1.650 1-1/2" 11 1.882 1-3/4" 11 2.116 2" 11 2.347 So anyone else talking crap about bolloking up perfectly good threads in sheer ignorance would be better off placing the method of thread "mixing" under the term: butchery. LOL Kind regards Iain Middlebrook Last edited by iain-hsm : 10th July 2008 at 20:30. Reason: Post didnt take the table
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