Author Topic: source for pressure tubing  (Read 730 times)

Offline petertha

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source for pressure tubing
« on: December 21, 2023, 04:27:51 PM »
I've consciously left the title rather broad in order to harvest input as much as possible. I'm contemplating running oil lines to specific parts of an IC engine. A scaled OD of say a full scale 0.250" OD line might be 0.062" OD. I have seen tubing in that range, but the fittings, generally for instrumentation or similar real world application, are ginormous. Like 5/16 or 3/8" hex nuts. Now it may well be that 0.062" may not flow what I need to flow or has other limits, but just generically wondering what is out there in the world of small lines?

I have seen/used 'plastic' lines that fit over barbed fittings, say 0.125"OD 0.0625"ID (or metric equivalent). Lines are available for air, water & also hydrocarbons depending on the tubing material, so no issue there. The barbs could be replicated to small fittings which look more at home on a model engine. Functionally would work, but not really the look of metal lines with more geometric bends etc.

- where do people source the typical copper lines & fittings I see on engines? I've pasted an example but I see them a lot on steam engines too. Are the tubing ends flared like I see on most real world applications? I think they have special nuts with specific angled seats? Do-able, but pretty fiddly.

- I considered a low brow solution where the line is permanently bonded to a slim fitting which mitigates threads & flares & nuts. But whenever the engine is disassembled one would snip the line, unscrew the fitting & replace. Seems wasteful. OTOH,it may only be a handful of actual fittings. 10 rebuilds over a lifeime may not be that bad.

Offline astroud

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Re: source for pressure tubing
« Reply #1 on: December 21, 2023, 05:06:13 PM »
Take a look at magomhrc.com, they do  hydraulic fittings and flexible tubing suitable for model excavators and down to 2mm dia with a range of fittings. If you want to use copper lines you may be able to adapt the fittings.
Though based in Spain I have ordered from them and experienced excellent service and high quliaty products.

regards   Andrew

Offline Jasonb

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Re: source for pressure tubing
« Reply #2 on: December 21, 2023, 06:22:55 PM »
Most Model Engineering suppliers will do copper tube down to 1/16" OD.

Usual way to connect is to silver solder on "nipples" sometimes called ferrules which have a 60deg taper on the end to make with a female taper on the fitting. The nipple also has a shoulder that the nut pulls against to close the joint.

See here for nuts an dnipples though not too hard to make yourself

http://www.steamfittings.co.uk/asp/components_subcats.asp?CatID=19

https://www.ekpsupplies.co.uk/brass-cones-for-union-nuts.html

https://www.ekpsupplies.co.uk/brass-union-nuts.html

Typical straight union that would go into a threaded hole in your crankcase etc

https://www.ekpsupplies.co.uk/brass-straight-single-unions.html

Offline petertha

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Re: source for pressure tubing
« Reply #3 on: December 21, 2023, 07:36:02 PM »
Thank You! One stop shopping at reasonable prices. Much easier than how I was going to proceed.

- I also see nice little pressure gauges starting in the 100 psi range. Is it safe to assume the copper tubing + brass cone + threaded fitting is collectively rated for this kind of pressure, or are the gauges intended for other applications? (clearly displaying my lack of steam knowledge).
https://www.ekpsupplies.co.uk/pressure-gauges.html

- Any special procedures to bend this kind of copper pipe like pre-annealing or sacrificial anti-kink core material?




Offline petertha

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Re: source for pressure tubing
« Reply #4 on: December 21, 2023, 07:40:08 PM »
Take a look at magomhrc.com, they do  hydraulic fittings and flexible tubing suitable for model excavators and down to 2mm dia with a range of fittings.

Thanks Andrew. Coincidentally I stumbled on similar links in my searching of miniature pumps, but I didn't pay attention to fittings.
I had no idea this facet of hobby existed & the (hydraulic) pressures they achieve are remarkable. Another good lead!

https://magomhrc.com/en/13-hydraulic-parts

Offline Jasonb

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Re: source for pressure tubing
« Reply #5 on: December 21, 2023, 08:41:51 PM »
They will be fine for 100psi and are what is usually used on steam locos and traction engines. You can also get metric ones if you buy from mainland Europe.

The RC site plant - diggers, cranes, trucks, etc is now quite popular

Offline Roger B

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Re: source for pressure tubing
« Reply #6 on: December 22, 2023, 07:29:54 AM »
I am using 2mm od 1mm bore copper tube with home made brass fittings at around 100 bar, 1500 psi in my fuel injection systems.
Best regards

Roger

Offline rklopp

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Re: source for pressure tubing
« Reply #7 on: December 22, 2023, 06:12:24 PM »
I recommend building a bender to make nice bends and prevent kinking. I built one from C. Horace Clarke plans http://www.opensourcemachinetools.org/archive-manuals/Mini_Tube_Bender-C_Horace_Clarke.pdf. It works very well, and is a good project in itself. There are other benders, some simpler and some even more complicated than Clarke's. The most complicated ones are mandrel benders that use a long slender mandrel with a bullet point reaching into the tube to the bending location to support the inner tube wall as it gets wrapped around the exterior saddle die.

Offline steamer

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Re: source for pressure tubing
« Reply #8 on: December 22, 2023, 10:49:00 PM »
I use "Type K" copper tubing for a lot of steam lines up to 160 psig.   Including boiler tubes

For smaller lines  (3/8" and 1/4") I use A/C copper tubing

Silver soldered of course

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

 

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