The Craftmans Shop > New from Old
Resurrection of a CFEI 100 KVA Induction Furnace
awemawson:
Thanks Pete - yes just Abi left - Hugo is much missed. He'd sit on the sofa pressing his back hard as he could against me then lean over backwards pushing his snout into my shoulder and neck. Silly but I miss those interactions.
vintageandclassicrepairs:
Hi Andrew,
So Sorry to hear about Hugo
It is so hard to lose a constant companion who always listens but never complains
I still get sad when I come across photos or reminders of our last dog "Dot" 7 years later
John
awemawson:
Thanks John.
The De-mineralised water has arrived for the replacement coolant but not yet the Glycol so I got on with a slight modification.
The furnace body needs compressed air to tilt it and if you find that your compressor has tripped out when the pot is full of molten metal and you can't pour it out it's all a bit embarrassing. So I've added a 'tell tale' pressure gauge in the foundry so at least I know that there's air before I start melting. (My compressor is in a Portakabin remote from the foundry)
As luck would have it my compressor is throwing a hissy fit at the moment and not turning off - yet to investigate - could be compressor not getting up to pressure or the switch unit not turning off - only time will tell !
Anyway I can't pressure up the gauge yet as the Loctite 542 has to cure for a few hours.
awemawson:
Today I started drawing off the remaining antifreeze solution from the tank - the replacement mono-ethylene-glycol hopefully will be here tomorrow so I can't put this messy job off any longer!
Theoretically straightforward but in practice a pain. I sucked the majority out using a 'wet and dry' workshop vac with the filter element removed, decanting it into drums but the last 15 litres or so had to wait in the vac until I'd been to the local amenity site and emptied the drums.
(The glycol solution is poisonous so needs proper safe disposal - spillages apparently break down in the air over about ten days which is just as well as when the burst happened a lot went on the floor and outside onto the concrete)
Then came the lovely job of wiping the slimy sludge off the tank walls - be dead easy if it wasn't for the pipes everywhere!
. . . anyway - it's done. I will purge the whole system with 'tap water' followed by demineralised water as the flexible pipes and generator cooling loops will still contain the old coolant, but I daren't do that just yet as we can't be certain of overnight frosts.
. . . more when the glycol arrives.
awemawson:
Now here's a conundrum: It's been a bit of a concern where the brown (presumably iron) contamination has got into the glycol cooling loop. There are one or two malleable iron fittings in the circuit so they are a possible source, but the heat exchanger has the 'non glycol' side cooled by bore hole water that definitely IS iron contaminated.
Were there a leak across the heat exchanger this could be another possible source - and now the tank is empty is my chance to do some tests. I reckoned that with the bore hole pump running and putting well water through the heat exchanger and the coolant pump not running gives the maximum pressure differential. Pop a cup under the glycol side of the exchanger and run the bore hole pump flat out. Now the return pipe from the plate exchanger drops vertically into the tank discharging at low level. There was a slight puddle under it from drips, which I dried away and placed a spray paint top under it, running the bore hole for 15 minutes.
The result was about 2 ml of liquid in the paint cap :bugeye:
Now here is the quandary - is this just glycol solution sitting in the pipework and plate exchanger and randomly dripping, or is it bore hole water that has leaked from cool side to hot side :scratch:
I honestly don't know - I tested the collected sample from the cap on my Brix freezing point refractometer and it gave the same reading as the removed coolant of minus 15 degrees centigrade. So this would suggest that it is just residual coolant sitting in the pipework - but IS IT ?
I think that I will have to do a pressure test with compressed air by doing a bit of plumbing tomorrow before re-filling the system.
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