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source for pressure tubing

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petertha:
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.

astroud:
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

Jasonb:
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

petertha:
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?



petertha:

--- Quote from: astroud 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.

--- End quote ---

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

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