The Craftmans Shop > New from Old
Resurrection of a CFEI 100 KVA Induction Furnace
awemawson:
Phil, they probably say 35 mBar to allow for a bit of loss in the pipe due to the flow - 2 mBar is peanuts.
But do you have any way of measuring the actual pressure when in use. I expect that it'll be lower than you expect !
awemawson:
Being a Saturday no more progress in sourcing the correct bedding compound for the tile - it's a very light, crumbly white material rather like Plaster of Paris but softer. I'm fairly sure that the gasket / cushion under the tile is a KAOwool type and that can be sourced easily in suitable sheets.
As for the bedding compound whatever I use needs obviously to stand up to the heat, give a good seal to the gas / air mixture between the plenum chamber and the perforated tile and yet be able to be dug out in the future to replace the tile (which really is a consumable). There are various high temperature silicone seals that look good on paper but I've never used them. However all the ones I've found say (oddly) not to be used as a gas seal despite being intended for flues :scratch:
I thought I'd try and 'size the problem' by laying the tile back in unsealed and ungrouted and see how much was actually escaping. In the picture you will see a blue fringe where the escaping gas / air mix has ignited, though interestingly now the flames no longer lift off the tile seat - this is probably due to the new regulator.
awemawson:
This stuff may be suitable
(comments welcomed!)
https://www.mapei.com/gb/en/products-and-solutions/products/detail/mapeflex-firestop-1200-c
hermetic:
Andrew, could that bedding material be there to dissipate the gas so that you get a flame out of every hole? difficult to photograph I know but it doesnt appear that the outer holes are burning? I have seen this dissipation layer in an ornamental gas fire we had which was supposed to look like a log fire. Also seen somwhere, gas burning on the surface of a bowl of sand which acted as a dissipation layer, but can't remember where. If so, would a layer of fiberglass or rockwool work?
Phil
Edit, where did you get your 4kgh regulator from?
awemawson:
Phil, as far as I can recall from about 20 years ago the layer under the tile was washer shaped with a 6" hole in the middle leaving all the holes exposed, and a 12" outer diameter matching the tile. But it had totally fallen apart as I didn't renew it all those years ago. I'll try to get an original one on Monday.
The regulator was from eBay - It's a Silverline 997865. I got it from a seller that just had the one, and it does seem that there is more than one version as some say 3/8 BSP and some 3/8 NPT and are undescisive as to whether it's LH or RH. Mine was NPT RH and cost me the princely sum of £7.95 !
In normal use the ceramic chips defuse the gas / air mix of course and add a bit of back pressure hence the outer holes come into play. In the picture, the holes opposite the pipe leading the gas / air to the plenum chamber are taking most of the flammable stuff.
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