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Heatshrink sleeving as a heat insulator for valve handles?

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Bryan Cedar 125/09/2021 22:00:59
82 forum posts
4 photos

I have run my Kingscale Std 4 for the first time and all went well except for the fact that I found the handles on the steam valves too hot to handle.

Can an kind member let me know if say two layers of heatshrink sleeving on the handles would help? This would be an easy solution as the handles are straight.

The gloves I had on simply melted where covered with grip rubber.

Paul Kemp26/09/2021 01:41:21
689 forum posts
18 photos

Just do what the big boys do and use rag or wear leather gloves! Aside from that and following full size practice also, fit wooded handles.

Paul.

not done it yet26/09/2021 07:07:16
6322 forum posts
20 photos

Even one layer would help to reduce the rate of heat transfer.

Personally, if I was thinking of two layers, I would use one heat shrink sleeve over an inner layer of insulation. Got to be better if the right sort of insulator is chosen.

Martin Connelly26/09/2021 08:06:09
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1889 forum posts
203 photos

The ATUM range of heat shrink tubing should be better than standard as it has an internal layer of hot melt adhesive that would secure it to the surface it was on.

Martin C

Ramon Wilson26/09/2021 08:50:00
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1194 forum posts
296 photos

Silicone tubing as used for model aircraft fuel tube is perfect for this problem. Unaffected by the temperatures involved and a good insulator. Comes in a variety of bore diameters, wall thickness etc and easy to slip on for use.

Not particularly visually aesthetic it's easily removed after use and can be used over and over.

Tug

Circlip26/09/2021 11:42:26
1353 forum posts

Handles used to be "Sleeved" with Tufnol.

Regards Ian.

Bryan Cedar 126/09/2021 12:41:29
82 forum posts
4 photos
Posted by Circlip on 26/09/2021 11:42:26:

Handles used to be "Sleeved" with Tufnol.

Regards Ian.

Hi Ian

Tufnol was my first thought but will try the heat shrink tubing first as much easier to do. A friend made his handles in Tufnol but it is almost a clockmakers job to achieve the very fine square sockets that my loco requires.

Calum Galleitch26/09/2021 13:21:20
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101 forum posts
27 photos

Two wee points about heatshrink: one, it only shrinks to about 50% of its size, so it needs to be carefully sized for the part. Second, over time it will lose the inherent tension it has when shrunk, and can slip if it's not mechanically secure.

I'd give the silicon tube serious consideration - it's easy to find in various sizes and colours and should be ideal, I would think.

Robert Atkinson 226/09/2021 15:56:34
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1086 forum posts
20 photos

ATUM of similar glue lined hestshrink is not a good idea as the glue will soften with heat.
Silicone rubber tube is a good option. The only issues are that it tends to be thick wall and most types have poor resistance to oil and grease.
If you want to try heatsink I'd suggest Raychem DR-25. This is a durable thick wall tube and will give reasonable insulation. As Calum points out it can loosen with time. The best solution for this is to use a thin layer of epoxy under the heatshrink. Try it without and if happy but it loosens replace it and use epoxy.

Robert G8RPI.

Gerhard Novak27/09/2021 15:19:28
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53 forum posts
63 photos

I agree with Robert that glue lined heat shrink is not a good idea as the glue will get soft and slippery every time the handle gets warm.

I wouldn't suggest an epoxy layer under the heat shrink tube, as there may be some chemical reaction between the epoxy and the heat shrink tube. Heat shrink tubes are mainly made from cross linked polyolefins, a long time reaction such as brittleness can not be excluded if they are in long time contact with other polymers, especially under elevated temperatures.

I would suggest to apply a heatshrink tube (or more then one) direct over the metal handle, or, if possible, produce wooden sleves which go over the handle.

Edited By Gerhard Novak on 27/09/2021 15:35:23

Martin Kyte27/09/2021 15:26:25
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2558 forum posts
45 photos

Just so you know, non adheasive heat shrink is 2 to 1 and adhesive heat shrink is 3 to 1.

regards Martin

Edited By Martin Kyte on 27/09/2021 15:26:46

Baz27/09/2021 15:57:03
578 forum posts
2 photos

There is a yellow plastic tube available very similar to the silicon tubing mentioned in earlier posts that is resistant to petrol. It is used on garden machinery for fuel feed from tank to carb. I have seen two sizes of it, may be more available but the larger one should do the job.

Peter Greene27/09/2021 16:46:11
287 forum posts
2 photos
Posted by Bryan Cedar 1 on 25/09/2021 22:00:59:

Can an kind member let me know if say two layers of heatshrink sleeving on the handles would help? This would be an easy solution as the handles are straight.

Seems to me this is one of those things (not uncommon here) that's easier to try than to spend two days discussing it.

My own feeling is that the material is too thin to be of much help even though it may be nominally a thermal insulator. Like the insulating washer between a power transistor and heat-sink. The washer material is actually an excellent thermal (as well as electrical) insulator - but at the thickness that is used it hardly matters.

bernard towers27/09/2021 19:24:31
293 forum posts
84 photos

a0f771c5-8a0f-42e1-9714-a3019348d739.jpegI’m for the tufnol ones like these9d6b02d1-b168-46ca-90c2-2ee036cee852.jpeg

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