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Boiler lagging

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Garry Coles19/04/2021 15:52:13
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97 forum posts
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Hi, The time has come to think about lagging the boiler on my 2 in D & NY traction engine. I have some kerwool which is about 1/4 in thick. But its to thick to use. Has anybody used anything else, like thick cardboard. Will the heat be to much for this type of material. Some of you will say, why don't I just buy some thinner stuff. Well the price may not be a lot, but the postage costs to Jerey are.

Any thoughts please.

Garry

J Hancock19/04/2021 16:00:49
724 forum posts

The coefficient of heat transfer for Balsa wood is impressively low.

Harry Wilkes19/04/2021 16:18:19
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1174 forum posts
64 photos

Hi Garry

On my 3" Burrell which I,m about to do there are 2 layers I would say without getting the rule out one is around a 1/4 the other 1/8

H

SillyOldDuffer19/04/2021 16:45:37
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7549 forum posts
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On a model locomotive boiler I feel insulation is more a statement of intent than likely to deliver a marvellous improvement! Some materials will be better than others, but they are all too thin to do much good. The insulation on a domestic immersion heater is 2 or 3 inches thick, and that's not fully effective either, even though the water is well below boiling point. Good insulation is bulky.

Always well worth having some insulation, but I wouldn't get too excited about the exact material or thickness beyond more is better! Most materials apart from soft plastics will withstand boiler temperatures, but Cerwool can't go wrong because it's made to get very hot! Can't find any Thermal Conductivity figures for it, but as it depends on trapped air, I guess it's similar to Balsa, which should be fine on a 200psi boiler.

Be interesting to experiment with various materials to see if any are outstanding, but I suspect the thermal performance of all common insulators at model scale thickness will be spoiled by the layer's thinness.

Dave

MichaelR19/04/2021 16:49:00
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443 forum posts
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Hi Garry,

On my Durham & NY I used Glass Fibre chopped strand mat, the type used for car body work patching, I had my engine a lot of years and the lagging showed no problems.

MichaelR

JasonB19/04/2021 16:53:51
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Not sure about thickness Dave, take a look at some of the multi layer house insulation products.

Two layers of 1/16" Kaowool with a sheet of tin foil between is a popular choice for 2" engines. Unless you have something handy I suspect postage costs on most things will be similar.

Garry Coles19/04/2021 17:45:35
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97 forum posts
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Thanks everyone. I will probably use some thick cardboard.

Bazyle19/04/2021 18:50:31
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6038 forum posts
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re cardboard, think about whether water will get in Even if it dries out next steaming will it affect the integrity of the material?

duncan webster19/04/2021 19:23:58
3508 forum posts
63 photos

The insulation is provided by the trapped air. What the insulation material (Kaowool etc) does is prevent convection, conduction through air is very low. Scrunched up aluminium foil is pretty good, or corrugated cardboard (not very water proof). Cork is pretty good as well, floor tiles?

Daggers20/04/2021 13:10:30
30 forum posts

I need some thin lagging in the end i purchased Kiln Glass Paper which is 1mm thick. I purchased a pack 50 pieces 80mm square for £5 just butted some sheets using double sided tape then brass cladding. Worked really well.

Brian Abbott23/05/2021 23:34:34
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488 forum posts
93 photos

Hello All.

Anyone know a stockist for the 1/16" thick Kaowool insulation?

Thanks

duncan webster24/05/2021 00:34:14
3508 forum posts
63 photos

ceramic paper

but it's comfortingly expensive. A phone call to explain what it's for might produce a sample. Otherwise find furnace engineers in your local yell and cadge some from them

or let ebay be your friend rcAAOxy4fVTB3xZ">cheaper

However I've no idea of its insulation properties

Edited By duncan webster on 24/05/2021 00:36:36

bernard towers24/05/2021 11:20:55
293 forum posts
84 photos

If it’s kaowool I split mine down on my DNY so it is about 5/32 thick.

bernard towers24/05/2021 11:20:56
293 forum posts
84 photos

If it’s kaowool I split mine down on my DNY so it is about 5/32 thick.

Brian Abbott24/05/2021 11:54:30
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488 forum posts
93 photos

Thanks Duncan.

I have ordered a roll of the 1mm,

As i only need a couple of meters if anyone needs a small amount for a project then drop me a message, token gesture towards the cost plus postage.

Thanks.

Robert Atkinson 224/05/2021 12:43:23
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1086 forum posts
20 photos
Posted by duncan webster on 24/05/2021 00:34:14:

ceramic paper

but it's comfortingly expensive. A phone call to explain what it's for might produce a sample. Otherwise find furnace engineers in your local yell and cadge some from them

or let ebay be your friend rcAAOxy4fVTB3xZ">cheaper

However I've no idea of its insulation properties

Edited By duncan webster on 24/05/2021 00:36:36

That ebay listing is much more expensive, £22 a meter compared than £2.83 !

duncan webster24/05/2021 13:35:15
3508 forum posts
63 photos

But if you only want a metre it's cheaper to buy from FleaBay

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