Resurrection of a CFEI 100 KVA Induction Furnace

[Sea.dog]

Very interesting read.
It describes the precise failure mode that you have, Andrew. A torque transmission seal where, at some time or other, the seal faces have bound together and, when the pump has been restarted, the stiction has been sufficient to unwind the spring a few turns thereby causing its failure.

[awemawson]

Yes Seadog and reading that article it seems using the spring is the later version, and the spare I've been supplied is the earlier one where there is positive drive from those pressed steel cups.

Well the kit seems to be compatible, anyway for better of for worse the pump is now back together - hoo-blooming-ray it's been a long time coming. I won't be able to test it's sealing abilities until the pump is re-installed, and that can't happen until the last of the plumbing arrives hopefully by the end of this week.

I assembled the O rings and seals with copious amounts of washing up liquid as a lubricant so no doubt it will froth a bit to begin with. But before that I finished the clean up of the internal components, and I must say they've shone up very well, far better than I expected 

[mattinker]

Hi Andrew,

It's good to see it going back together again! If there was a like button I'd use it! Are you planning on casting iron? Looking for ward to seeing it working!

Cheers, Matthew.

[awemawson]

Matthew, at this rate I'll be glad just to get a bit of old steel bar glowing in the crucible !

Long way to go yet. Hopefully the Chiller will soon be sorted, but I need to start deciding on a layout in the foundry. Chiller needs  to be plumbed to the Furnace Driver which is then plumbed to the Furnace Body where the actual crucible is and all need heavy cabling and pipes and can't really be moved once set up. In the case of the Furnace Driver, which has the major amount of electronics in it, I need access to all four sides (all open up as panels) for testing in the initial phases.

As yet the foundry only has lighting wired in, I left the power side until I know where things are going to settle. Then somehow I need to move the 110 KVA generator into the stable over it's wonky floor, level it up and duct it's output across the back of the workshop into the foundry.

The foundry still has too much other junk in it for comfort. Some things such as the big pottery kiln are justifiable for lost wax burn out, but much else has to find another home. Trouble is it has accumulated junk over the years as it wasn't in use.

In there there is still the Hodge Clemco 'outdoors' grit blaster with it's crates of bits, a trolley mounted sheet metal nibbler, two rather nice beechwood foundry benches, two racks of shelves, two sets of oxy-acetylene . . . well you get the idea !

. . . so how long do I have to stay in isolation . . . . . . ?

[hermetic]

. . . so how long do I have to stay in isolation . . . . . . ?

Until all your projects have been completed for our entertainment and satisfaction!

Good Luck Andrew, stay Healthy!
Phil

[awemawson]

Thanks Phil. Loads more 'stuff' shifted from the Foundry building today (lucky that  I re-roofed that Portakabin a while back!) but still loads more to move but I need to find homes for it 

[awemawson]

So hoo blooming ray the long expected 100 mm length of 1" BSP threaded stainless pipe arrived today. Supposedly from Southern Ireland but it was wrapped in the usual 'I've come from China' packaging. - I reasoned that it must have been packed well over the 72 hours the virus can survive for so it was 'probably' safe.

This allowed me at last to do a dry assembly trial fit as I need to arrange the 15 mm pressure control back feed to the tank via the gate valve at 35.5 mm off the base. Once that was proven possible I was able to slice off the remaining bit of vertical plastic pipe with some confidence that I can bond onto the stub and still be able to get the pipes assembled. In practice the 15 mm pipe has ended up about 5 mm too low, but I think that there is sufficient flexibility in the system to accommodate that.

The Christmas Tree of plumbing has been assembled on the bench with Loctite 542 and once that is fully cured I can trim the last bit of the plastic stub and  solvent glue that on.

. . . slowly slowly . . catchee monkey 

[awemawson]

The Loctite 542 having cured I was able to re-assemble the pump plumbing in the chiller and make the solvent weld joint to the original plastic pipe. This itself needs to cure for 24 hours before I can fully tighten the various other joints and finally re-connect the motor and run a test.

I hope to heck that that seal works after all this faffing about 

[John Rudd]

Confidence, confidence.... .      As Dennis said, ' it'll be alright on the night...'

Just dont forget....as I'm sure you won't....Dont run the pump dry!! Or bye bye seal...

Good luck..

[awemawson]

John the seal is laced with washing up liquid at the moment and I will initially put just a bit of water in the tank and turn the pump by hand using it's cooling flange before any power is applied.

First thing is to slowly fill the tank and watch for static leaks, and to that end I've just resurrected a hose pipe point not too far away (O ring seals totally crunchy after a few years in direct sunlight), and I've reconnected the motors wires and bolted it's flange down.

So if I can persuade her tomorrow it'll be wife on the tap and me with hose in the tank 20 yards away yelling STOP 

[awemawson]

So some good news and some rather bad news

I filled the tank - no leaks and all seemed well. I spun the pump by hand by means of its cooling fan - still OK.

Then I applied 3 phase to the machine - sure enough pump running, and the controller showing current water temp - the main cooling  fan then started and I noticed that it was spinning the wrong way - warm air should exhaust at the top, and be drawn through filters at the sides, but it was going the other way. Checking the Grundfos pump, it too was spinning the wrong way so obviously a phase reversal. But by this time the cooler had  reduced the water temperature to 5 degrees.

So I reversed two phases and now pump  and big fan now spinning the correct way - the compressor however made a funny noise and tripped its breaker 

It does look at the moment that the compressor has died, and this could be terminal for the entire project due to cost. I've walked away from it to allow my head to clear - a quick look on eBay reveals a few similar but not identical compressors starting at £250 but even if I got one I'd need it to be installed and re-gassed. Installation would be far from easy as it is tucked away in a cramped space.

. . . . . one step forwards . . . five backwards 

As I filled the tank the float for the water top up inlet valve, that I had noticed was on the base of the tank, floated up and I ws able to recover it - it looks as though it should just snap back into place but that's the least of my problems at the moment.

[John Rudd]

Oh Dear!...This is not good....Yet you've come so far...

Is it worth getting your compressor 'fettled' ? versus the price of a replacement of dubious quality? Do you know anyone in the refrig game that could connect and regas as a home job?

Here's hoping you can rescue it...

[awemawson]

John it's all up in the air at the moment - it sounds as though the motor itself has blown up and of course they are a sealed unit.

I >MAY< try reverting to the reversed phases briefly as it was working then ! But at the moment I'm giving it a wide berth !

[awemawson]

Well I did revert to the phases the other way round - still kaput as you might expect.

Intriguingly two phases are drawing about 90 amps before the breaker trips, and the third phase is drawing no current 

I think that it's 'proper sick' - shame it's a sealed unit like a normal 'fridge one (but on steroids!)

[russ57]

A diy regas? Depends I think on what the gas is.

-Russ

[John Rudd]

A diy regas? Depends I think on what the gas is.

-Russ

If you can buy the gas...

[Sea.dog]

You didn't state it explicitly, But I assume that when you first connected with the phases wrong that the compressor did work, is that correct?

If so it's strange that simply reversing the direction has caused it to fail.

[awemawson]

Graham I think the phase reversal was just co-incidence as the starting current was pretty massive. Not sure how these sealed units operate - this one is apparently a four cylinder model - but years ago it definitely worked with the phases connected such that the pump and fans were spinning in the correct direction.

Recently before it failed, and with the Grunfos pump and fans spinning the wrong way, the refrigerant unit was working and cooled the water tank from 8 degrees down to 3.5 degrees. So I'm not sure how the internal pump in the sealed unit works. Reading the manufacturers documents they are NOT sprinkled with dire warning re direction .

The internal motor has failed I'm sure evidenced by the enormous current it's drawing (90 amps on two of the phases!) so sadly it's a bit more than just re-gassing it .

[Sea.dog]

That's really bad news, Andrew. I've no idea about the internals of this type of pump, but I'd assume they're a reed valve or something similar, so direction shouldn't be an issue.

I stand to be corrected.

[awemawson]

I understand that the sealed unit compressor / coolers have an oil charge and a gas charge within the envelope.

When I re-built the Grundfos pump there was a tide mark of 'something' that had dried to a hard varnish like substance (indeed I think that's what did for it's seal & spring) and I'm just getting this nagging doubt whether the immersed bit of plumbing in the water tank from the compressor unit has sprung a leak, released the oil into the water which over the years evaporated leaving the varnish tide mark.

This would of course explain the demise of the compressor (no oil) but if this is the case I'm surprised that it did actually chill the water and I was not aware of masses of  bubbling in the tank from an alleged leak.

. . . this is forensic engineering !!!!

[Sea.dog]

I think we need to organise crowdfunding to keep this project rolling. You've come too far to drop it all now 

[russ57]

) so sadly it's a bit more than just re-gassing it .

Sorry, should have been clearer. I thought you said you had found a replacement but regassing was the barrier.
Even though the replacement was not as ruggedly built,  given its likely use (ie, sporadic, not continuous as would be for say a cold store) would it be 'good enough'
Of course, original refrigerant (r12? ) may be illegal to work with without a licence, but later types seem to be available as diy.
Although not trivial...


-Russ

[awemawson]

Graham, what a nice thought!

Russ, I don’t think sourcing a replacement equivalent unit would be too much of an issue apart from the cost. They seem to be north of £1500 new, and dubious used ones pop up starting at £250 /£750 mark though none are identical.

Before committing anything like that sort of money I some how need to get a bit of confidence that the rest of the furnace equipment is reasonably sound. I do remember that when the furnace driver was delivered I was able to connect it to one of the furnace bodies and get the electronics to ping and determine the resonant frequency. At the time I had no chiller and no high power 3 phase supply in fact I was running off a Transwave static converter off a 13 amp socket!  Obviously I couldn’t go any further without a massive power source.

So I think probably my next objective is to repeat that experiment.

[mattinker]

I think we need to organise crowdfunding to keep this project rolling. You've come too far to drop it all now 

I'm with you on this Seadog!

Before committing anything like that sort of money I some how need to get a bit of confidence that the rest of the furnace equipment is reasonably sound. I do remember that when the furnace driver was delivered I was able to connect it to one of the furnace bodies and get the electronics to ping and determine the resonant frequency. At the time I had no chiller and no high power 3 phase supply in fact I was running off a Transwave static converter off a 13 amp socket!  Obviously I couldn’t go any further without a massive power source.

So I think probably my next objective is to repeat that experiment.

 
This sounds like a good plan!! Looking forward to the results!!

All the best, Matthew.

[russ57]

Ah. OK. I read your previous post as saying that a replacement was gbp 250 - 1500 is a different matter....

-Russ