Resurrection of a CFEI 100 KVA Induction Furnace

[awemawson]

So today's task - get the Raydyne furnace body off the wobbly dolly and moved to the final resting place. Splits into several phases:

Phase 1 : clear a path from the tractor shed through the stable and round the corner to the foundry. Miscellaneous junk in  the stable was easy to shift, but on the track to the foundry roller shutter were two boxes of fencing bits that could only go out back through the now cleared stable. The 90 degree bend from stable to foundry track can only JUST be navigated by the fork lift, and then only with the forks fully up to clear the bore hole pump brick enclosure - OK Phase 1 completed.

Phase 2: get fork lift in position over the furnace - avoid putting several tons of forklift on the roller door threshold strip and squashing it flat, and lifting too high and taking out the door mechanism or a purlin - to avoid these obstacles I had to roll the dolly / furnace closer to the door and resort to only using one tine to lift with - not good practice.

Phase 3: (the Egyptian Phase !!) lower furnace onto scaffold pole rollers now that the dolly has been removed - roll, skid and manhandle into position. Got it too close to the wall initially - the pipes rubbed the 'Big Six' wall cladding on the way down  - OK moved

It was surprisingly easy to move - (remember single handed) and is now hopefully in its final resting place.

I'd just finished and was tidying up to receive a phone call from a friend telling me that he now has positively located the 4" asbestos cement downpipe that will let me make a better arrangement to keep those pesky pipe off the airline - so that's good 

[tom osselton]

That’s a nice looking unit

[awemawson]

Thanks Tom, and the beauty is, it's molten metal at the push of a button. The ingot I cast yesterday was ten minutes from starting up the generator to switching it off again.

OK it was only aluminium and only just over a kilogram but so much less hassle than oil or propane.

I still need to organise the ergonomics of pouring . . but getting there!

[awemawson]

I had a sudden brain wave - could I manage to sort out the cable movement when tilting using a 'tool balancer' ?

This would relieve the weight of the pipes / cables (never quite sure to know what to call them as they are both pipes and cables !) and I had a vague recollection that I had one tucked away in the welding shop.

Sure enough there it was slowly corroding away on a damp shelf - oh there are TWO !  Both rated at 4.5 kGs but no idea what sort of weight I'm dealing with. Slipping an old set of bathroom scales under a loop of the cables gave me a 4.9 kg measurement but of course as the cable is raised you take more of the weight. But at least in the right order of magnitude. So worth setting up an experiment.

First a 'high point' from a length of 50 mm box section clamped to the structure of the foundry, then suspend a balancer from it with a big Ty-wrap. No not enough lift. OK double up and try both. Yes we are in the ball park and it looks promising - a bit more lift and a better way of adjusting the suspension.

So the hunt is on for a 15 kg balancer (they seem to be adjustable downwards from their rating) - I can fabricate a suitable suspension bracket and will need a nice soft sling to cradle the pipe and I think we may had a solution.

[awemawson]

The anti-frost trace heating got a mild test this morning, which I'm glad to say it passed

Air temp was -2C as was the metalwork in the foundry. The exposed handle bit of the ball cock that burst was at +3C and the upper fittings on the heat exchanger were at +5.

OK only a mild frost but so far so good.

[Pete.]

How about a length of decent bungy? I might have some that could be suitable.

[awemawson]

Pete it might well, thanks for the sugestion.

I've just won a used 9-15 kg adjustable balancer on eBay - if that doesn't work out I'll be in touch 

[awemawson]

Just a tiny bit of progress today.

The Munson Ring pipe clamps that I ordered have arrived so I've managed to fit the length of 3" non-inflammable down pipe across the rear chassis member to prevent the high frequency cables coupling with the braiding of the air hoses. Pretty simple except the air pipes had to come off to tap the holes and I cut the pipe too long first time so it rubbed on the air hoses as the furnace was raised. Trimmed an inch off and re-fitted - seems to work OK now

Although the more powerful 'Tool Balancer' has arrived I ran out of  enthusiasm so it's not yet fitted. I need to create a more permanent suspension point for it.

[awemawson]

This morning I found a suitable offcut of 3"x3" angle iron, drilled a few holes and bolted it to the foundry structure as a support for the 15 kg balancer. A bit crude as it's not triangulated and only held in place by a single M12 bolt but I think it's adequate.

Seems to work OK

[awemawson]

This wasn't meant to happen

Feeling a bit low, so this morning to cheer myself up I'd intended to do a quick melt reducing some scrap aluminium to ingots - all going well, generator purring away, furnace beginning to melt the aluminium (running @ 30 kW) - then I noticed water - heck turn off quick 

Obviously the coolant water that goes through the coils of the induction furnace was pouring onto the floor from the bottom of the 'furnace body'

Thankfully I've erred on the safety side of things, every thing bonded together electrically, and there were no dramas but it was a bit of a worry.

So, furnace driver shut off, generator stopped, bore hole water pump stopped and I can start to sweep the large volume of water off the floor and to outside. It's circulated at 50 psi so a lot comes out in a short time.

Looking at the case of the furnace body water level in the asbestos cement box has risen to the level of one of the vent holes so it must be an internal failure rather than the outside driver pipe/cables. Internally there are short lengths of flexible pipe insulating and coupling the plumbing - hopefully it's one of those that has failed rather than the embedded coil itself. I'll investigate later when things are a bit drier.

. . so why was I feeling a bit low? Yesterday I very sadly had to put Hugo, one of my dogs to sleep. He had developed a tumour close to his heart and really it was the kindest thing to do. But I feel I've lost much more than just a pet - he was a good friend. Those of you who've been here will know he was very posesive of me, grumbled if anyone else sat on the sofa next to me and was very perceptive of what I was thinknig and doing.

[awemawson]

Water level subsiding so I took off the back of the box. In the words of Wes (*)

"There's Your Problem Lady!"

One of the 13 mm pipes has come clean off its copper tail - now as you can see in the picture these are retained by plastic hose clamps - years back I found that steel ones got too much magnetic coupling and got too hot!

Need to test that the coil is free flowing and that it wasn't a blockage that caused it to come off.

(* This is a quote from 'Watch Wes Work' on YouTube - he repairs vehicles in a rural part of America and previously was a CNC machine repairer so has a very logical and resourceful approach to fault finding - well worth watching)

[edward]

Sorry to hear about Hugo, Andrew. Its a massive kick when a good friend like that passes. My two are the only company I have while working at home all day so I can understand how you feel. Sad times

I too am addicted to Wes. He reminds me of you in a way, cool, logical, not phased by repairing things. The only thing that horrifies me is the state of some of the 'vehicles' he works on - a product of salty roads and no state inspection I guess, but that these things share the roads with other people is really quite scary.

[Pete W.]

Andrew,

My lovely but shy assistant (LBSA) and I offer our condolances on the passing of Hugo.  I fear I can't remember if he was a 'V' or a 'W' but in either case I can't spell it!

There are five German Shepherd Dogs and at least one 'Heinz57' interred in our back garden.  (And three cats.)  One GSD and the Heinz57 passed before LBSA and I were married but we both mourned the passing in turn of the most recent four GSDs.  Making that final decision is always hard, however well one can rationalise it, it's a life so always an awesome responsibility and always painful.

LBSA has talked herself into walking our neighbours' two dogs twice a day, usually three days a week, sometimes five, because the dogs would otherwise be left alone all day with no stimulation and no exercise.  She very much takes the dogs' side!!
 

[Sea.dog]

So sorry to hear about Hugo, Andrew. I remember sitting on the sofa with him...

Re the pipe problem. I'd not be happy with a straight pipe stub and pipe that softens with heat. Surely a barbed end would be preferable?

[ddmckee54]

Re the pipe problem. I'd not be happy with a straight pipe stub and pipe that softens with heat. Surely a barbed end would be preferable?

Or maybe just soldering a ring of copper wire around the existing copper stub?  Something that would give the plastic hose clamps a little more traction against slippage.

[Spurry]

It seems, at times, that we are much kinder to animals than humans.

On the proper topic, what about say 3 olives spaced out and soldered onto the stub?

[awemawson]

Thanks chaps for your kind comments re: Hugo

Possible pipe blockage discounted - coil uncoupled and 'blown through'

Yes I was thinking perhaps an 'olive' or two soldered to the stub of pipe would be effective. I've been trying to find photos (from when I grouted in a replacement crucible) of the 'other end' of the flexible pipes to see if the native stubs on the coil are barbed or not but have drawn a blank. I have a spare coil assembly - I'll dig it out and see what it has.

A quick calculation knowing the system pressure is 50 psi and the pipe about 1/2" gives a 'pushing off' force of just under 10 lbs so not enormous, but as Graham said the pipes warm up.

As the stubs are just into a compression fitting I may just turn up some barbs anyway.

I noticed a few weeks ago that the coolant was far from clear - with a brownish tinge - I cannot remember whether it was tap water (probably) or demineralised water with a good dose of ethylene glycol as an antifreeze. Googling induction furnce coolants there are dire warnings not to use automotive antifreezes which I'd intended to use for it's corrosion inhibiting properties. The brown tinge I think can only be iron salts (*), and the walls of the holding tank have a thin brown slime layer that probably is the same. As far as I can tell the majority of the water passages are copper, a bit of brass in places, and a small amount of cast iron in the housing of the circulating pump. Borax has been suggested but I'm loathe to start making up my own concoctions.

Certainly a major clean out and flushing is called for before melting restarts. And the antifreeze will need replacing.

(* when I noticed the brown tinge I thought it might have been coming from the bore hole water, which IS iron laiden but the plate heat exchanger isolates this from the circulating coolant)

[awemawson]

A quick foray into the Tractor Shed reveals that the spare coil has indeed got 'olives' soldered on the ends of its centre tap pipes.

Now this coil is not identical to the one currently fitted but was made by the same manufacturer, so it's probable that this is how the 'other end' is terminated.

[awemawson]

First job this morning - remove the 15 mm copper stubs that introduce the coolant to the coil assembly and sweat on olives to give better retention (hopefully).

(Slightly delayed by having to re-wire the cleaners hoover cable YET AGAIN - traded for cleaning the loo in the workshop !)

Olives fitted, stubs refitted, pipe re-installed and the back of the furnace body given a good blow out with dry compressed air so that any leaks during testing would be more easily detected.

Fingers in my ears I started the Grundfos circulating pump. Tank level is very low as most coolant had previously ended up on the floor but is high enough to feed the pump. Pressure rose to the set point (50 PSI) and there were no dramas of pipes popping off thankfully. Both magnetic flow sensor 'torpedoes' were in their raised position indicating that both coolant circuit have flow. I left it running for a few minutes and no apparent leaks - tank was frothing due to the low level making the return pipe above the water level.

So I need to let it all thoroughly dry out, flush out and clean the coolant circuits and replace the coolant. I have 50 litres of Mono-Ethylene-Glycol on order and also 50 litres of demineralised water all of which should arrive early next week.

[Pete.]

Sorry to hear about Hugo Andrew. You've only the puppy left now?

I hope he's as comfortble with my Rosie as your other two were. They were both lovely characters.

 

[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 

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

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.