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Post by talltuk on Mar 22, 2015 14:16:57 GMT -8
Hi folks. Ok, I know this is a basic question and that with all my reading and conversations with my fellow roketeers on here I should know the answer but I need a little reassuring.
I just chucked a load of money on a mixed batch of 88 reclaimed firebricks. They are old and have no guarantees but fingers crossed they will do for mucking around with. Would using these surrounded by 50mm thick rockwool batt do for a cheap and cheerful batchbox core?
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morticcio
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"The problem with internet quotes is that you can't always depend on their accuracy" - Aristotle
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Post by morticcio on Mar 24, 2015 1:13:28 GMT -8
The firebricks might be up to it but the rockwool isn't suitable for insulating the riser.
You're not going to get the performance using low grade materials so in my opinion it is false economy to use them.
A 6" batch box core doesn't need too many 1260C grade firebricks. Moving forward, it might be worth investing in these & a box of superwool. Alternatively for the riser use insulated firebricks. You can use the other firebricks for the bell?
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Post by Dan (Upstate NY, USA) on Mar 24, 2015 4:05:15 GMT -8
I used rockwool in my riser works good in my stove... feeling the heat at my back right now... link |
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Post by pinhead on Mar 24, 2015 7:08:29 GMT -8
The rockwool just may work as long as it's slightly "protected" by the firebrick. It won't stand to direct contact with flame, though, that's for sure.
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Post by shilo on Mar 24, 2015 7:29:28 GMT -8
rockwool is for 700c
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Deleted
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Post by Deleted on Mar 24, 2015 8:38:16 GMT -8
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morticcio
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"The problem with internet quotes is that you can't always depend on their accuracy" - Aristotle
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Post by morticcio on Mar 24, 2015 9:51:31 GMT -8
If you read further down it says rockwool may be able to withstand temperatures up to 1,000°C but at that temperature the fibres start to melt.
Personally I would choose a different material which isn't going to degrade when exposed to very high temperatures for extended periods of time.
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Deleted
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Post by Deleted on Mar 24, 2015 10:53:59 GMT -8
Leucite rich basalts have high melting points. Fiber manufacturers would not melt their stuff at 1500° if the melting point would be a lot lower, as every degree costs them money. Rockwool insulation is made up of at least 95% stone wool and it has a melting point above 1,000 ºCwww.rockwool.com/files/rockwool.com/Environment/PDF%20-%20Environment/Sustainability_brochure.pdfbasalt fibers have properties akin to S-glass. A common use is in the fire protection sector because of its high melt-point. Fire-blocking tests performed by Basaltex placed its basalt fabric in front of a Bunsen burner, placing the yellow tip of the flame in direct contact with the fabric. The yellow tip reaches temperatures of 1100°C to 1200°C (2012°F to 2192°F) and causes the fabric to become red hot, similar to a metal fabric. When exposed to the flame, basalt fiber maintains its physical integrity for extended periods of times, but the company found that a fabric made of E-glass with the same density can be pierced by the flame in a matter of seconds. www.compositesworld.com/articles/basalt-fibers-alternative-to-glassBasalt FAQs smarter-building-systems.com/smarter-building-basalt-faqs/ |
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Post by talltuk on Mar 25, 2015 8:53:35 GMT -8
Thanks guys. The plan is to build the core and riser out of the reclaimed brick, godknows what their rating is. Then wrap the entire thing in rockwool. I will upgrade to high spec but this is purely experimental at the moment so I have a very small budget
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Post by satamax on Mar 25, 2015 22:38:55 GMT -8
Talltuk
No worries. There's even examples of direct exposure of rockwool, and it lasted somewhat.
Rockwool should be contained to last, as the fibers can whistand the heat, but not the binder.
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Post by satamax on Mar 25, 2015 22:41:06 GMT -8
And for the europeans, who see air entrained concrete often, when protected by split firebricks, it's good insulation for the firebox.
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Post by talltuk on Mar 26, 2015 15:18:23 GMT -8
Ta Max. If the testbed works well I can justify spending some real cash to make the entire thing from new materials.
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