Threadtypes - wich are best for diving?

Hanssing · 27th February 2008, 21:41

Hi Guys,

I originally thought that I would keep the standard regulator-hoses with adaptors for any modification. But after a few oring-blowouts and leaks lately, I went looking for someone to professionally crimp the hoses.
And I can get them made as long as I provide the barbed ends.

We all know that the most common used threads in diving are
3/8"-24 UNF O-ring sealed - (Unified Screw Thread) for 1st.-stage ports.
9/16-18 UNF O-ring sealed swivel for regulator-connection.

I have now severeal times had leaks from those damn orings, so I'm thinking that perhaps for custom applications theres a better thread with regards to robustness? So insted of using manifold-blocks with 3/8-UNF I could use whatever I would like.

My guess is that most tapered threads will do better since they seal better than an oring, but theres also the non-tapered versions wich are not oring-sealed.

So if there were no difficulties associated, wich thread would you use for lowpressure hose-routing on an Rebreather?

Standard Oringsealed UNF types (3/8 and 9/16)
1/4" NPT - Nationalstandard Pipethread Tapered. American standard-thread.
BSPP - British Standard Pipethread Parallel (O-ring?)
BSPT - British Standard Pipethread Tapered.
G-type (European) - Is actually normally used abbreviation for BSPP
R-Type (European) - Is actually normally used abbreviation for BSPT

.... or something else?

BTW:
Please do tell where you get hose-barb connection for the different thread-types...

Regards
Nicolai

cramerdn · 27th February 2008, 22:26

NPT threads are designed to produce a seal when some sealing material is used, like teflon tape. NPTF, F for fine, will seal from the deformation of the threads and do not require sealing material. NPT and NPTF can be mixed but you don't get the "F" seal.

OceanOpportunity · 27th February 2008, 23:31

I've been using various NPT threaded fittings. They're secure. Think about it...many, many fill station designs incorporate NPT fittings. These run at very high pressures ( to 5000 psi in some cases), so have no fear about a good seal. One inconvenience to consider is that if you plan on making routine configuration alterations, it's a little work to clean the threads and re-tape before securing the fitting again. If you do go NPT, its worth teh extra money to get fittings that swivel. a hose that ties in to your rig at both ends will be difficult to replace unless one end can swivel. From experience...you'll eat through alot of hose, and have some very twisted hose routings without them!

Hanssing · 28th February 2008, 09:14

Quote: (Originally Posted by OceanOpportunity)

One inconvenience to consider is that if you plan on making routine configuration alterations, it's a little work to clean the threads and re-tape before securing the fitting again.

Yeah, that was my assuption as well, that tapered threads would be better as long as you dont take them apart often....

Quote: (Originally Posted by OceanOpportunity)

If you do go NPT, its worth teh extra money to get fittings that swivel. a hose that ties in to your rig at both ends will be difficult to replace unless one end can swivel. From experience...you'll eat through alot of hose, and have some very twisted hose routings without them!

Yes, but I really want to avoid any orings if possible, so no swivels if not needed. In the configuration as planned, there's only one hose where this could become a problem (Manifold to Manifold), so by installing this first I can avoid any twisting. All the other hoses end in some sort of QC, so the will not twist.

So, I'm now very much leaning towards tapered threads as expected.
Two posibilites:
BSPT 1/4" or NPT 1/4"

I can get BSPT male with 1/4" hosebard from CEJN (Their fittings series 900).
Can someone provide a retailer with 1/4" hosebard NPT fittings?
Preferably in europe.

Thanks
Nicolai

Stephane · 28th February 2008, 09:33

Hello Nicolai,

Undersea UK (http://www.undersea.uk.com/catalogue/catalogue.pdf) has re-usable fittings with G1/4, 3/8-24UNF and 1/4NPT threads (5045 series) or 9/16-18UNF (5046) for 2nd stage connection.
This allows you to use a scuba hose cut at the right dimension.

**Dave Sutton** · 28th February 2008, 10:30

Tapered pipe threads with teflon (PTFE) tape is about as bulletproof as can be. 1/8 NPT fittings are easy to get, and if needed I can send you the tap for the holes (if you cannot find the tap in Europe). The 1/8 NPT is the same physical size as 3/8-28, but is non O-Ring sealed. I use it for almost everything.

1/4 NPT is WAY too big... don't even think about it. Yes I know you can get adapters and hoses made with it. You'll hate them. Trust me here. Buy a bag of barbed fittings in 1/8 NPT male, some Oetker crimps, a crimping tool, and make your own hoses. McMaster-Carr has it all, and it's cheap. If you need stuff sent, just let me know and I can make up a complete kit for you, including bulk hose in green for 02 and blue for diluent.

Dave

Hanssing · 28th February 2008, 12:10

Quote: (Originally Posted by Stephane)

Hello Nicolai,

Undersea UK (http://www.undersea.uk.com/catalogue/catalogue.pdf) has re-usable fittings with G1/4, 3/8-24UNF and 1/4NPT threads (5045 series) or 9/16-18UNF (5046) for 2nd stage connection.
This allows you to use a scuba hose cut at the right dimension.

Yup, I know....
But I'm vary of those reusabel ones.... I'd rather have them crimped correctly.

The whole point is to avoid unessecary orings, get the most robust connection, and thereby hopefully get a tough'er system. Otherwise I'd just go with GolemGear adaptors and UNF threads with orings.

Been in contact with different supplies, and CEJN kan actually make NPT-hosebarbed ones, if you order enough, but its hard to get a threadcutter.
But if I use European R-thread I can get the cuttingtools and hose-adaptors cheap and easy - no one here will have anything to do with NPT....

Cheers
Nicolai

Hanssing · 28th February 2008, 12:34

Quote: (Originally Posted by Dave Sutton)

1/4 NPT is WAY too big... don't even think about it. Yes I know you can get adapters and hoses made with it. You'll hate them. Trust me here. Buy a bag of barbed fittings in 1/8 NPT male, some Oetker crimps, a crimping tool, and make your own hoses.

Well I had a complete order at a place called LDSOH, but the deal seemed to have fallen through?

Anyway what's the internal diameter of the 1/8"-NPT with 1/4"-hosebarb?
If its close to the UNF-3/8-24 then its good enough for breathing-supply.

Quote:

McMaster-Carr has it all, and it's cheap. If you need stuff sent, just let me know and I can make up a complete kit for you, including bulk hose in green for 02 and blue for diluent.

McMaster-Carr, McMaster-Carr, it all you american people ever talk about. Why cant they open a store here in EU ?

Nicolai

Edvin M · 28th February 2008, 13:02

I dont know about how you have it in Denmark but in sweden there is almost always a simple 1/8 NTP threadcutter in the "normal" boxes with a few different threadcutters, dont ask me why, it doesnt make any sense to me my why there is. The only NPT thread that is "common" here is 1/4 that is used in some plumbing and compressed air applications although the non threaded is quite more common.

OceanOpportunity · 28th February 2008, 14:01

There are NPT fittings with swivels that do not use o-rings.

Both the 1/8NPT and 1/4NPT are produced with barbs that fit 1/4" inside diameter hose. This is effectively the same as dedicated scuba hoses, and just fine for breathing. I agree with Dave that 1/8NPT is ideal from the perspective of keeping things as clean as possible. However in some instances you may end up using a few 1/4" fittings. For example, I use a manifold block that has 1/4" NPT inputs and 1/8" NPT outputs. Not ideal, but it cost me $11 versus whatever the dedicated 'diving manifolds' are. Works perfectly.

On hoses...these NPT fittings with 1/4" barbs fit standard scuba hoses. In some cases, I wanted to salvage an end fitting from a regulator hose, so I chopped off the 3/8UNF end and fit an NPT fitting. Easy to install, and easy to crimp. Very secure, no leaks, and saves mega bucks on custom hoses. The colored hose from McMaster is rated at 250psi...basically twice the pressure that it wil actually see when diving...works great, and being color coded is a nice step towards standardizing something that should be between all rigs (IMHO).

I can also help you get McMaster parts. PM me with whatever you are interested in.

Cheers,
Mike

27th February 2008, 21:41	#1 (permalink)
Hanssing flap-flop ..... flap-flop Current Rebreather/s: rEvo Other Rebreather/s: rEvo Join Date: Nov 2005 Location: Denmark Posts: 430	Threadtypes - wich are best for diving? Hi Guys, I originally thought that I would keep the standard regulator-hoses with adaptors for any modification. But after a few oring-blowouts and leaks lately, I went looking for someone to professionally crimp the hoses. And I can get them made as long as I provide the barbed ends. We all know that the most common used threads in diving are 3/8"-24 UNF O-ring sealed - (Unified Screw Thread) for 1st.-stage ports. 9/16-18 UNF O-ring sealed swivel for regulator-connection. I have now severeal times had leaks from those damn orings, so I'm thinking that perhaps for custom applications theres a better thread with regards to robustness? So insted of using manifold-blocks with 3/8-UNF I could use whatever I would like. My guess is that most tapered threads will do better since they seal better than an oring, but theres also the non-tapered versions wich are not oring-sealed. So if there were no difficulties associated, wich thread would you use for lowpressure hose-routing on an Rebreather? Standard Oringsealed UNF types (3/8 and 9/16) 1/4" NPT - Nationalstandard Pipethread Tapered. American standard-thread. BSPP - British Standard Pipethread Parallel (O-ring?) BSPT - British Standard Pipethread Tapered. G-type (European) - Is actually normally used abbreviation for BSPP R-Type (European) - Is actually normally used abbreviation for BSPT .... or something else? BTW: Please do tell where you get hose-barb connection for the different thread-types... Regards Nicolai __________________ Woohooo - I can change my rEvo! Its going to be bitchin' tricked out piece of gear Last edited by Hanssing : 27th February 2008 at 22:07.
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27th February 2008, 22:26	#2 (permalink)
cramerdn Obey my dog! Current Rebreather/s: Evolution Dolphin Other Rebreather/s: Dolphin Join Date: Dec 2006 Location: Townsville QLD Posts: 730	Re: Threadtypes - wich are best for diving? NPT threads are designed to produce a seal when some sealing material is used, like teflon tape. NPTF, F for fine, will seal from the deformation of the threads and do not require sealing material. NPT and NPTF can be mixed but you don't get the "F" seal. __________________ "Its better to live one day as a tiger than an entire life as a worm." "But who's ever heard of a worm skin rug?"
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27th February 2008, 23:31	#3 (permalink)
OceanOpportunity for a world of water Current Rebreather/s: Other CCR Dolphin Home Build Other Rebreather/s: Not Bought Yet Inspiration Classic Other CCR Dolphin Home Build Join Date: Nov 2006 Location: Providence, RI USA Posts: 596	Re: Threadtypes - wich are best for diving? I've been using various NPT threaded fittings. They're secure. Think about it...many, many fill station designs incorporate NPT fittings. These run at very high pressures ( to 5000 psi in some cases), so have no fear about a good seal. One inconvenience to consider is that if you plan on making routine configuration alterations, it's a little work to clean the threads and re-tape before securing the fitting again. If you do go NPT, its worth teh extra money to get fittings that swivel. a hose that ties in to your rig at both ends will be difficult to replace unless one end can swivel. From experience...you'll eat through alot of hose, and have some very twisted hose routings without them! __________________ Michael Lombardi Oceans of Opportunity www.oceanopportunity.com Elected Director, Society for Human Performance in Extreme Environments MN'07, The Explorers Club Project Manager, Diving a Dream
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28th February 2008, 09:14	#4 (permalink)
Hanssing flap-flop ..... flap-flop Current Rebreather/s: rEvo Other Rebreather/s: rEvo Join Date: Nov 2005 Location: Denmark Posts: 430	Re: Threadtypes - wich are best for diving? Quote: (Originally Posted by OceanOpportunity) One inconvenience to consider is that if you plan on making routine configuration alterations, it's a little work to clean the threads and re-tape before securing the fitting again. Yeah, that was my assuption as well, that tapered threads would be better as long as you dont take them apart often.... Quote: (Originally Posted by OceanOpportunity) If you do go NPT, its worth teh extra money to get fittings that swivel. a hose that ties in to your rig at both ends will be difficult to replace unless one end can swivel. From experience...you'll eat through alot of hose, and have some very twisted hose routings without them! Yes, but I really want to avoid any orings if possible, so no swivels if not needed. In the configuration as planned, there's only one hose where this could become a problem (Manifold to Manifold), so by installing this first I can avoid any twisting. All the other hoses end in some sort of QC, so the will not twist. So, I'm now very much leaning towards tapered threads as expected. Two posibilites: BSPT 1/4" or NPT 1/4" I can get BSPT male with 1/4" hosebard from CEJN (Their fittings series 900). Can someone provide a retailer with 1/4" hosebard NPT fittings? Preferably in europe. Thanks Nicolai __________________ Woohooo - I can change my rEvo! Its going to be bitchin' tricked out piece of gear Last edited by Hanssing : 28th February 2008 at 12:15.
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28th February 2008, 09:33	#5 (permalink)
Stephane Stéphane Acounis Current Rebreather/s: rEvo Other Rebreather/s: rEvo Join Date: Nov 2005 Location: Nantes - France Posts: 788	Re: Threadtypes - wich are best for diving? Hello Nicolai, Undersea UK (http://www.undersea.uk.com/catalogue/catalogue.pdf) has re-usable fittings with G1/4, 3/8-24UNF and 1/4NPT threads (5045 series) or 9/16-18UNF (5046) for 2nd stage connection. This allows you to use a scuba hose cut at the right dimension. __________________ Stéphane
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28th February 2008, 10:30	#6 (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: Threadtypes - wich are best for diving? Tapered pipe threads with teflon (PTFE) tape is about as bulletproof as can be. 1/8 NPT fittings are easy to get, and if needed I can send you the tap for the holes (if you cannot find the tap in Europe). The 1/8 NPT is the same physical size as 3/8-28, but is non O-Ring sealed. I use it for almost everything. 1/4 NPT is WAY too big... don't even think about it. Yes I know you can get adapters and hoses made with it. You'll hate them. Trust me here. Buy a bag of barbed fittings in 1/8 NPT male, some Oetker crimps, a crimping tool, and make your own hoses. McMaster-Carr has it all, and it's cheap. If you need stuff sent, just let me know and I can make up a complete kit for you, including bulk hose in green for 02 and blue for diluent. Dave __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com Last edited by Dave Sutton : 28th February 2008 at 10:34.
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28th February 2008, 12:10	#7 (permalink)
Hanssing flap-flop ..... flap-flop Current Rebreather/s: rEvo Other Rebreather/s: rEvo Join Date: Nov 2005 Location: Denmark Posts: 430	Re: Threadtypes - wich are best for diving? Quote: (Originally Posted by Stephane) Hello Nicolai, Undersea UK (http://www.undersea.uk.com/catalogue/catalogue.pdf) has re-usable fittings with G1/4, 3/8-24UNF and 1/4NPT threads (5045 series) or 9/16-18UNF (5046) for 2nd stage connection. This allows you to use a scuba hose cut at the right dimension. Yup, I know.... But I'm vary of those reusabel ones.... I'd rather have them crimped correctly. The whole point is to avoid unessecary orings, get the most robust connection, and thereby hopefully get a tough'er system. Otherwise I'd just go with GolemGear adaptors and UNF threads with orings. Been in contact with different supplies, and CEJN kan actually make NPT-hosebarbed ones, if you order enough, but its hard to get a threadcutter. But if I use European R-thread I can get the cuttingtools and hose-adaptors cheap and easy - no one here will have anything to do with NPT.... Cheers Nicolai __________________ Woohooo - I can change my rEvo! Its going to be bitchin' tricked out piece of gear
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28th February 2008, 12:34	#8 (permalink)
Hanssing flap-flop ..... flap-flop Current Rebreather/s: rEvo Other Rebreather/s: rEvo Join Date: Nov 2005 Location: Denmark Posts: 430	Re: Threadtypes - wich are best for diving? Quote: (Originally Posted by Dave Sutton) 1/4 NPT is WAY too big... don't even think about it. Yes I know you can get adapters and hoses made with it. You'll hate them. Trust me here. Buy a bag of barbed fittings in 1/8 NPT male, some Oetker crimps, a crimping tool, and make your own hoses. Well I had a complete order at a place called LDSOH, but the deal seemed to have fallen through? Anyway what's the internal diameter of the 1/8"-NPT with 1/4"-hosebarb? If its close to the UNF-3/8-24 then its good enough for breathing-supply. Quote: McMaster-Carr has it all, and it's cheap. If you need stuff sent, just let me know and I can make up a complete kit for you, including bulk hose in green for 02 and blue for diluent. McMaster-Carr, McMaster-Carr, it all you american people ever talk about. Why cant they open a store here in EU ? Nicolai __________________ Woohooo - I can change my rEvo! Its going to be bitchin' tricked out piece of gear
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28th February 2008, 13:02	#9 (permalink)
Edvin M RBW Member Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Aug 2007 Location: Lysekil, Sweden Posts: 121	Re: Threadtypes - wich are best for diving? I dont know about how you have it in Denmark but in sweden there is almost always a simple 1/8 NTP threadcutter in the "normal" boxes with a few different threadcutters, dont ask me why, it doesnt make any sense to me my why there is. The only NPT thread that is "common" here is 1/4 that is used in some plumbing and compressed air applications although the non threaded is quite more common. Last edited by Edvin M : 28th February 2008 at 13:05.
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28th February 2008, 14:01	#10 (permalink)
OceanOpportunity for a world of water Current Rebreather/s: Other CCR Dolphin Home Build Other Rebreather/s: Not Bought Yet Inspiration Classic Other CCR Dolphin Home Build Join Date: Nov 2006 Location: Providence, RI USA Posts: 596	Re: Threadtypes - wich are best for diving? There are NPT fittings with swivels that do not use o-rings. Both the 1/8NPT and 1/4NPT are produced with barbs that fit 1/4" inside diameter hose. This is effectively the same as dedicated scuba hoses, and just fine for breathing. I agree with Dave that 1/8NPT is ideal from the perspective of keeping things as clean as possible. However in some instances you may end up using a few 1/4" fittings. For example, I use a manifold block that has 1/4" NPT inputs and 1/8" NPT outputs. Not ideal, but it cost me $11 versus whatever the dedicated 'diving manifolds' are. Works perfectly. On hoses...these NPT fittings with 1/4" barbs fit standard scuba hoses. In some cases, I wanted to salvage an end fitting from a regulator hose, so I chopped off the 3/8UNF end and fit an NPT fitting. Easy to install, and easy to crimp. Very secure, no leaks, and saves mega bucks on custom hoses. The colored hose from McMaster is rated at 250psi...basically twice the pressure that it wil actually see when diving...works great, and being color coded is a nice step towards standardizing something that should be between all rigs (IMHO). I can also help you get McMaster parts. PM me with whatever you are interested in. Cheers, Mike __________________ Michael Lombardi Oceans of Opportunity www.oceanopportunity.com Elected Director, Society for Human Performance in Extreme Environments MN'07, The Explorers Club Project Manager, Diving a Dream
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