Understanding types of copper?

[DianneB]

I am working on a 1" scale boiler and was planning to use 1/4" Type L copper for flues and have the tube sheets made to accommodate 3/8" O.D. flues but have found it very difficult to find 1/4" Type L up here in Grandmother's Land. I have used Type L copper before and it is easy to use for flues.

"Soft copper tube" is available in most hardware stores and has the same O.D. but it is difficult to track down the specs on hardware tubing so gawd knows what the wall thickness and strength are like. Straightening it would also seem to be a P.I.T.A. since it comes in coils.

Any advice on selecting material for flues?

Thanks gang!

[Soot n' Cinders]

I went to my local plumbing supplier, Ferguson Plumbing here, and bought American made type K copper pipe for my flues, granted mine are 7/8" OD. Id be leery of hardware store copper, too much of it is chinese junk these days.
Id try and find a plumbing supply house near you and buy from them, it will be much better material than what Home Depot/Lowes carries

[gwrdriver]

I would agree with Soot on all counts . . . see your local pipe supply/plbg house and order seamless rigid Type K tube, or McMaster-Carr should have it. I always use Type K for it's thicker wall and, assuming good initial workmanship and proper care later, a longer life expectancy.

[DianneB]

I find that plumbing suppliers carry 1/2 and above but not the smaller diameters.

I tried ordering from McMaster & Carr but they don't' ship to Canada and the border is 2 hours away

[hoppercar]

Type k hard drawn tubing is available from both McMaster carr and msc industrial supply...it's easily rolled in, and the best thing to use

[Carrdo]

Dianne,

Had a quick look on the internet. Did you try New West Metals Inc.in Winnipeg? Their toll free number is 1-800 665-7625 . They have no minimum and will cut to length and deliver to your door. They have hard drawn copper tubing in straight lengths, types K,L, M.

Don

[DianneB]

Did you try New West Metals Inc.in Winnipeg?

I am waiting to hear back from them and also from another local metal dealer before I go to "extraordinary lengths" to get my copper tube!

[steamup]

3/8" OD hard copper is not a normal plumbing copper size but is used readily in refrigeration. Check with a supplier that deals in refrigeration supplies. I have bought ACR hard copper for refrigeration use. Basically ACR is type L that has been cleaned and capped with a dry nitrogen purge.

I would caution using 1/4" OD flues in a 1" engine. I have a 1" camelback 0-4-0 with 1/2" OD (3/8" ID) flues and they are none to large when fired on coal. It is a good steamer but soot buildup can slow things down. If you are firing propane you might get away with 1/4" OD but remember your surface area that transfers heat is much less and you will require more tubes to compensate.

[Harold_V]

Do keep in mind, tubing and pipe are not measured the same way until the size exceeds 12". If you inquire of ¼" tubing, it will have a ¼" outside diameter, while ¼" pipe will be larger, as it is measured by the bore. This could prove to be a fatal mistake if you improperly place an order. Don't use those two terms (tubing and pipe) as if they are interchangeable. They are not.

H

[Bill Shields]

Extraordinary lengths is when you order it from the UK...as I do for 5" and above tubing...and 7/16" OD thick wall tubing for flues.

Be CAREFUL about tubing sizes as Harold mentions. In many places they still use SWG for wall thickness.

There WAS a time when 3/8 tube was 3/8 OD because tube was tube and pipe was pipe...

I have found that 7/16 OD tube is very good for 1" scale boiler. If you can find it in North America, I would recommend it....for anthracite.

[James Powell]

I know my dad has just run into this in a 30 year old project- it has a range of (I assume 7/16, 1/2 and 9/16") tubes for the flues, and is a tad bit hot in the smokebox as a result.

That's because the previous to that boiler he built was with 3/8" tube, and it steamed like a constipated elephant. As in, it didn't at all well...

I have a copper boiler here with 1/4" tubes, but it is a vertical boiler, and the L/D's for vertical boilers are much lower than horizontal boilers. Unless you are building a vertical boiler, I would strongly recommend staying away from 1/4" tube in use as flues. Just way too small, unless gas fired.

James

[DianneB]

The boiler design (Cornish) I am working on is to be gas fired and the flues are only 6" long so the L/D ration is only 24. By Harris's book (which I have used before with considerable success) I should get the steam production that I am looking for.