Repacking type 4 heat exchangers

Discussion in 'Mech Tech' started by Mark Darby, Mar 14, 2019.

  1. Think Snotts has nailed his colours to the mast there :D
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  2. I won’t be able to get that image out of my mind now :(
  3. Aha, so they eventually reached you in sunny Lyon?
  4. Indeed they did, I collected them from the other Andy in York and brought them back. Belated thanks for them by the way.
  5. The originals used a woven fibreglass mat over an alloy reflector. IMG_3976.JPG

    The repro ones just used a but of recycled alloy
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  6. And @Mark Darby 's just thrown his in the bin ;)...
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  7. :eek:

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  8. It is asbestos ..had it tested came back as Crysotile (asbestos ) if you use fibreglass that could still break down and fragment and be inhaled gets f hot inside those exchangers .
    It's a type of fine netting surrounded by foil but it breaks up in time . The buses are all old now and were never really expected to last this long .

    The scary thing is that it's been blown directly into your face ...and any other unsuitable material will do the same .
    Mark Darby likes this.
  9. Actually still have the reflector bits. They're OK but I'm probably going to source something to remould. Presumably any thin aluminium or alloy will do.
    Last edited: Mar 14, 2019
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  10. When i took mine apart they were so full of oil and stuff there was little chance of any asbestos blowing around , In the end i used high temp silicon sealant to keep the aluminium sheet from rattling against the outer case. Not sure if it was the right thing to do but I do get heat in the cab and no oil smell:)
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  11. Just thinking ....what about using a metal scouring pad type material and stuff that in .
    You could get a welding torch on it just to test it's reaction on heat exposure . But still use the aluminium to case it in so it's not directly on the fins .
  12. I doubt if a metal scouring pad would be much insulation and put a welding torch to it and it will burn. That Calcium-Magnesium Silicate insulation I linked to earlier is good for 1260°C, sandwich it between thin aluminium sheets and mould it to shape. And now I see what the originals are like there’s probably no need to do more than cover the insulation with one sheet of aluminium.
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  13. Can it be guaranteed to not give off a toxic or a smell when heat is past through it . It will certainly take heat but when it gets blown up to your face ....has anyone used it .

    I didn't bother with mine just encased it with that alloy sheet ...i only ever use the heater if driving at night in the summer when it cools off a tad .
  14. I used plumbers mats in mine. Wouldn't recommend it as initially it smoked for a good 100 miles or so. Bit unpleasant but... it did work very well. Ive a write up on here somewhere.
  15. Mark Darby likes this.
  16. That’s a good question.

    Short answer - I don’t know.

    Longer answer - Calcium-Magnesium Silicate is non-toxic and shouldn’t degrade below 1260°C, that’s about double the maximum exhaust temperature as it exits the cylinder head and at the outside of the heat exchanger fins the temperature is probably no more than 100°C (ordinary paint doesn’t burn off). I’m reasonably sure that there would be less risk to health compared to the original material used but it would almost certainly give off some fumes or smell when new.
    Mark Darby likes this.
  17. I like the mesh that Dicky used; it would be easier to form than a solid sheet.
  18. This is from the technical data sheet for what they call the HT Paper version of this product (it comes in various thicknesses):
    Description: It has excellent thermal insulation characteristics and exceptional handling properties. Very flexible and resistant to tearing, it is particularly suited to all applications requiring further processing (laminated composites, die-cutting, rolling, folding). The organic binder burns out cleanly on the first firing at approximately 300°C, with ignition starting at 180°C. It has a good resistance to tearing and to thermal shock. It has a low shot content, is smooth on both sides and has a very low thermal conductivity. It is not affected by the presence of molten aluminium and has no reaction with alumina based bricks in application within the range of the typical use temperature.

    I also had a look at the Blanket version which has no binders to burn off:

    RS Pro thermal insulating sheet measures 2400 x 610 x 38 mm and is made from Superwool 607 fibre. It has a flexible blanket of high temperature insulation wool. It contains no binder or lubricant that can cause fumes which comes with flexible and resilient of good resistance to tearing - easy to wrap around hot equipment. Features and Benefits • 128 kg/m³ density • Thermal Conductivity 0.08 (at 200°C) 0.12 (at 400°C) W/m.K • Thermal stability and low heat storage • Efficient insulation for temperatures of up to 1200°C • Excellent thermal insulating performance

    I like this version as it is a bit thicker and I might also use it to wrap the air ducts to the front as well.
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  19. Looks very similar to the stuff I found in my mum's storage heaters. Kind of squishy silica stuff. Heatproof, and doesn't smell.

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