Resurrection of a CFEI 100 KVA Induction Furnace

The Craftmans Shop > New from Old

<< < (88/171) > >>

hermetic:
could you try a vacuum cleaner sucking in the opposite direction to the flow? I guess you will have tried the airline both ways, but just a thought!
Phil

awemawson:
Yes Phil the wet and dry vac was much in use as it also saves dumping all the coolant on the floor. All bits that could be sucked out were (behave in the back Jones Minor!)

But now I'm even more puzzled than before - I went out after supper to strip off the QD connectors - they were all free and passing my 'blow' quite happily, yet earlier those lower ones weren't :scratch: Have I dislodged something - no I don't think so as I'd have seen it come out.

I now think that the 'furnace body' has been exonerated, but it's VERY strange.

Now the output from the furnace driver has four 3/4" BSP fittings for electrical and cooling connection. A&B on the top line and B&C on the bottom. The electrical connections are a massive pair of copper straps 'B to C' and 'A to D' but coolant I think passes from A to B and C to D

It all gets VERY confusing as seeing the back of the panel where all this happens is neigh on impossible due to a mass of pipe and hoses, but one of them has a distinct kink - is the kink enough to completely block the pipe? I have (again!) no idea but that going to be my line of investigation tomorrow.

Oh joy I thought that this was nearly finished :bang:

Have a picture of my spare Furnace Body coil - you can see the two pipe connections in the middle - there is no passage between them, they connect to top and bottom threaded fittings. All irrelevent now if it's not the fault anyway

awemawson:
A long and very confusing day :

- I was determined to precisely map out the coolant water flow from inlet manifold (from chiller) through the Furnace Driver with it's monitoring flow gauges, out to the Furnace body via the Brewers Hose / Cable assemblies, back into the Furnace driver and eventually returning to the Chiller. Now within the Furnace Driver there is an absolute tangle of hoses as not only is the Furnace Body water cooled, but the power semi-conductors and tuning capacitors have cooling plates and a radiator / absorber for the low power electronics.

Now the pipes can be seen at a distance through the left hand door, and most terminate or originate on two manifolds under a shelf at the front again through a door. By grasping a hose by inserting a 'litter picker' between the 415 volt buss bars (power isolated!) I could wiggle it, but not quite see the other end. If I could remove that shelf . . . Seven bolts later the shelf was free EXCEPT whoever built this machine bored a hole in the shalf and ran a cableform through it. Every other thing passing through the shelf has a notch so the shelf would still come out - but not this one :bang: No room to make the hole into a notch. Desperate times, so I started to plan rigging up a web cam when one of the multitude of visitors that have come today proved to be a useful extra pair of eyes :thumbup:

So - plumbing map made and various tests performed. One necessitated pulling the pair of flow sensors slightly off the right hand panel to disconnect it's hose. It has a proprietary low profile hose clip allowing it to go through a small panel hole not much bigger than the pipe itself. It had to be replaced with a Jubilee clip, and the panel hole filed to accommodate the clip going back through !

OK - Tests showed NO blockage so I turned my attention back to the Furnace Body that I'd partially dismantled yesterday. I re-tested and proved flow through both it's water circuits, so all VERY odd - what was the previous fault as these things don't just 'go away' :scratch:

While I had the Furnace Body apart I decided to have a close look at the Quick Disconnect fittings. Shortly after I'd installed them years ago I became aware of a problem with their retaining ball bearings - some were corroding very badly - I assume being a fitting suitable for water that they are stainless steel. I came to the conclusion that despite the fitting having a brass body, at times the balls were carrying some of the huge currents hence the damage. My modification was to put a link of 70 mm CSA cable round the fittings, with suitable female hex pillars brazed to their adaptors.

Well of course those balls are still grotty so today I found out how to dismantle them, the intention being to order up some definitely stainless replacements. The balls that I took out were in a shocking state and accurate measurement wasn't possible. They were 'about' 1/4" or 6.35 mm but the corrosion and pitting gave readings from 6.1 to 6.6 mm! Just on the off chance I had a look in my 'might come in useful' bearing box, and for some obscure reason had a bag of 'about 1/4" ' balls - no idea what they are left over from, but they measured 6.33 mm and were magnetic so presumably not stainless. Well they fitted nicely, the QD worked like new and this confirmed me in my suspicion that the originals were 6.35 / 1/4". a bag of 100 now on order from Simply Bearing, delivery due tomorrow :thumbup:

So the plan now is to re-assemble everything, wet it up and do some flow testing (when the balls arrive)

. . as I said, a confusing day :hammer:

russ57:
I dont quite follow the flow diagram. The arrows don't 'flow', and one of the 2 blue 'one way' elements has contra flow..

-russ

Sea.dog:
Blue is cold and red is hot, to state the obvious. I think that Andrew said that the pipe pairs are A&B and C&D. Therefore you have two cold lines in and two hot lines out.

Navigation

 Message Index

Go to full version