Bauer KA20 restoration project

[drcolyn]

I have acquired a Bauer KA20-20ED air compressor that was scrapped due to ÅÔuspected hydraulic lock damage after the automatic condensate drain system failed. The company that usually services it failed it on suspected damage without actually stripping it (because of the high cost of labor) and sold a new smaller model in stead. I would like to restore this unit and I am currently in the strip down and assessment phase.
I did some investigation on the history of the compressor and found the following.
The hour meter looks original and shows 605 operating hours.
Info on compressor nameplate:Yahr 1976 Lt/min 600 Bar 350 Rpm 1450 Kw 15 Psi 4700
Cfm 21.2 Model KA20-20ED Nr 526-3031 Nr on crank case 5/80/3
I can see punch marks on the barrels and crank case to indicate fitting direction so I suspect the compressor has been worked on before.
The compressor was used to fill 300 bar BA sets at the risk department and it would typically have been the once a week duty of the fire and rescue paramedic on night shift.They bunch empty cylinders together so filling sessions will typically last 30 min at the least. I thus deduce that this boils down to about 1200 load cycles since 1976.
I found the following markings on the filter tower, water separator and inter stage filters.

Filter tower
Name plate on body:
Herst. nr 51477
Teile nr 061082
Betreibs druck 350 bar
Herst Jahr 1990
Filter tower cap:
51477
AL MG S/1F31
CH 5031

Water separator
On body:
Bauer Munchen KB064300
350 bar 0,57ltr 50ä BJ 1990
AL MG Si 1F31 CH5423
FAB NR 51201
On Top:
51201
AL MG S11F31
5689
On Bottom:
8979
ALSIMG 1 F31

Inter stage filter 2
On Body:
Max 25kp/cm2

Inter stage filter 3
On Body:
Bauer Kompressoren
80 bar 0,32l ALMg Si 0,5
1974 / 001
14150

Could you deduce from above mentioned information if this filter tower and water separator is listed in the Bauer tables for cyclic loads on pressure vessels as I am not sure which number to use.
They have me thoroughly warned with that photo on their web site of a filter tower that exploded. It reminded me of the end of a missile that has exploded. (I did military service in the artillery regiment and had to sweep the training grounds for live ordnance that was left over after training practice)
According to Bauer aluminum vessels has to be replaced on account of age (older than 15 years) alone.
Is it worth having them tested as these vessels only did about 600 load cycles maximum but I donÃÕ want to waste money to have them inspected if they are scrap anyway. Do you know the reason why the aluminum vessels only have a 15 year lifespan?
I plan to fit a gearbox and replace the 15 Kw 3phase motor with single phase one. I am in no hurry with regards to filling speed and I guess it will be better to speed down a 4 stage giant than rev up a 3 stage midgit? I spoke to a local service agent and he recons that it will not pump at a lower speed due to the blow by. Is there a minimum speed to running a compressor like this?
Wish I could get a small American surplus military model but this is Africa and I have got make do with what I have.
Finally - is anyone able to tell me how much oil the KA20 requires when filling it from scratch? I suppose asking for a operators manual will be wishfull thinking.

Regards
David Colyn

 

[CraigAClark]

Can you post pictures of the separators? It appears the that filter tower was added/replaced sometime around 1990 as the word Jahr=year and my guess is that Herst=manufactured. Also druck=pressure and I'm guessing that betreibs=working. If that is the case it will be nearly impossible to know how many actual hours are on the filter tower. However, if I recall correctly, the cyclic life of that model is 15,000. Just guessing at this point.

Craig

 

[windyairman]

How about some photos ?
i have spare parts catalogue if it helps.
Pm me

 

[windyairman]

Show photo of the clutch type also.
clutch operation manual,electric operated,or rotation spring type ?

 

[drcolyn]

Hi Craig

Sorry for not getting the foto's yet. I estimate that the water separator and filter tower could not have done more than 1200 cycles (which is about a 10th of it's usefull life)since being replaced in 1990. This compressor is a 1976 model with only 605 hours on the clock confirmed by the agent in SA. My question is the following - do you guys also think they should be replaced on the age factor alone? Bauer says 15 years regardless and a have very scary photo on their website to persuade those in doubt. I just don't know if that failure was due to safety valve malfunction or metal fatigue.

 

[CraigAClark]

If you go by the current standards that Bauer has set, the answer is yes, replace them. However, I have seen many used machines sold without any regard to "life" of components in the filtration system. Machines that were trade in, military surplus, going out of business etc. Many had very low hours, some none at all. Several had been rebuilt 1 or more times. The only instances that I can recall where filter towers were added, new or used, were when the machines had no filtration at all. Most were sold with the existing, original (in most cases) filtration systems. I honestly believe that your question rarely comes to mind, with both sellers and buyers.

Price being the biggest concern for most buyers, sellers are not motivated to add additional expense to the machine. Maybe you have generated a great topic for discussion.

Craig

 

[drcolyn]

Update on KA20 restoration project

Does anybody have advice on what degreaser I can use to clean all that old compressor oil and gunk off the parts before applying new oil for reassembly? I don’t want to leave a residue that will contaminate the new oil in any way. The KA20 takes 6 to 8 litres of oil so multiple oil changes will be very expensive.

As I stated before the compressor was scrapped due to suspected consequential damage from a hydraulic lock after the automatic moisture drain system failed. I was not convinced since the compressor was never stripped to determine the exact extent of the damage and I bought it for double the value of the scrap metal. The compressor turned freely and the oil in the oil pump was clear. During further inspection at home I had a good scare when the oil that came out of the sump was a murky brown green sludge so I just had to strip it down to the chassis.
What a relief to find the inside of the compressor block in perfect condition. The local Bauer agent knows this compressor’s history and confirmed that the 605 hours on the clock is correct since 1976!
I suspect the sludge is due to cold/irregular oil changes and the culprit for the “hydraulic lock” was actually the 15kW motor bearings seizing up. The front bearing can not be greased after it is bolted to the compressor and a grease nipple was never fitted. The motor have been running intermittently with only the initial bearing grease in it. The stator runs freely (another sign of bearings without grease) if spun by hand and you can hear the ball bearings bumping against each other as if there is no bearing cage. This spells good for my initial idea to replace the 15kw 3phase beast with a flywheel and single phase motor like the smaller compressors since the rewinding cost of the motor will probable scare off any possible buyers so that I can get a smaller unit that will be more suitable for home application. The only other parts that need replacement is the water separator (over 15 years old) and the 2nd and 3rd inter stage filters that has black soot in then like the inside of my house’s chimney.

Sorry for not posting photos but its all bits and pieces now.