Boiler lagging

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

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

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

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

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

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.

Thanks everyone. I will probably use some thick cardboard.

re cardboard, think about whether water will get in Even if it dries out next steaming will it affect the integrity of the material?

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?

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.

Hello All.

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

Thanks

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

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

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

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.

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

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