Thinking of buying a compressor...

[pescador775]

Your experiences are pretty close to mine. Ya gotta watch that 'displacement' con. Like the Joker said, 'who do you trust?'.

 

[pescador775]

Normally, the Junior's 2nd and 3rd stg valves last about 5 years. After that, they are subject to sticking or freezing up and generally causing an Excedrin headache. However, by following this tip your valves will last 10 years. After filling the last tank and draining filters, run your compressor under 'no load' with interstage tap closed and final filter drain tap open. Do this for about 10 seconds to expel moisture from the 2nd and 3rd stage valves.

Baurer, when asked, says 'don't do dat!'. Their concern is that the third stage plunger is banging around in its barrel when under no load (tick, tick, tick). However, my experience in working on and servicing these compressors is that this slight impact is irrelevant and has no ill effect provided it's not overdone. (To be perfectly truthful, I don't know what 'overdone' is since I've never seen one damaged from this practice).

 

[Genesis]

the taps slightly closed on the interstage drains (just enough to have a bit of pressure) and get effectively the same result with no banging from the third stage.

It also allows the final stages to cool down some (since they're not compressing significantly) which helps prevent the valves from getting clogged up as well.

This is easier to do if you added interstage pressure gauges (you can then SEE what each is producing) but you don't really need them - you can tell when the unit is effectively running unloaded.

The other useful thing to do is get a pedestal fan and point it at the cylinders. When you shut down the unit's fan stops, which means no cooling - the unit heatsoaks. The external fan is left on for a few minutes, which prevents the "heatsoak" from occurring and also lengthens component life.

 

[The Curly One]

From my expereince all of the compressor manufacturors try to put their compresors in the best light. They are a little optimistic on their CFM figures, even the ALKINs I sell. I have had people tell me the Max-Air puts out more CFM than the ALKIN or Bauers. That is certainly not true at all they are just way more bold in the advertising department. I do believe that the ALKIN is closer to the advertised CFM than any of the others and it does not have to turn over 2000 RPM to obtain it. I think the ALKIN puts out more actual CFM than the Max-Air or the Bauers. The ALKIN also has a much higher maximum PSI. I also believe that the ALKIN is the quietest and most durable.
Maybe someone is using "Fuzzy Math" but their "4.2 CFM" is less than the ALKIN 3.5 CFM for sure. My apologies for jumping into this univited but I am able to see that all that is advertised may not be true. I would gladly advertise the ALKIN as 3.35 CFM if Max-air would advertise theirs as 2.75 CFM actual. Should they advertise that their compressor weighs less then the ALKIN then I could not argue that point as that is true. Once again sorry for jumping in I just want everyone to be able to compare apples to apples. Curly

 

[pescador775]

Hey, Curley, jump in with both feet. Always glad to hear an informed opinion.

 

[pescador775]

I built my first portable compressor from Airforce takeouts and a Briggs and Stratton engine when it became apparent that the performance of commercial portables like the old Bauer Purus were way unsatisfactory. I'm talking 1972. When they were selling units that would put out 1.5 cfm my homemade machine jammed 3.8 cfm and weighed 85 lbs, only about 10 pounds more than the Purus (due to the extra filtration and crash frame). While the gap has been closed I'm not overly impressed. I still use this same homemade compressor. However, I recently changed out the original Kidde pump mfgt in 1952 to a 'new' design pump made in 1958. I paid $250 for the pump which I bought in the 'aircraft parts' section of EBAY. I cleaned the unit and straightened some cooling fins. I started to do a typical overhaul, basically removing the heads and barrels and checking the pistons, valves and springs. However, things looked so good that I stopped at cyls three and four and didn't bother to check 1 and 2. I had to build a new front support and add a 1/4 inch block under the drive adapter (outboard bearing mount) to make it fit. Fired it up and checked a few things. So far as I can tell performance is like new. Fills a '80' in 21 minutes.

The unit doesn't quite put out the rated 4 cfm because the engine is only rotating about 3150 rpm. If I could figure out how to change the linkage on the governor I might just go ahead and speed it up. No hurry, though.

A few years ago, I helped a friend locate a Bauer U-10 for a cheap price. The unit weighs about 110 pounds and is very reliable. However, when he told me the unit produced 4.2 cfm I started to feel a bit chagrined. The commercial guys had surpassed my little homemade! Subsequently, I found out that the Bauer company was blowing smoke. By careful reading of the definitions of 'SCFM' it became apparent that the Bauer which was rated 4.2 SCFM actually only produced 3.5 cfm actual free air or what USED TO be defined as SCFM. I felt better after that.

 

[Spray25]

pescador775 once bubbled...
I built my first portable compressor from Airforce takeouts and a Briggs and Stratton engine when it became apparent that the performance of commercial portables like the old Bauer Purus were way unsatisfactory. I'm talking 1972. When they were selling units that would put out 1.5 cfm my homemade machine jammed 3.8 cfm and weighed 85 lbs, only about 10 pounds more than the Purus (due to the extra filtration and crash frame). While the gap has been closed I'm not overly impressed. I still use this same homemade compressor. However, I recently changed out the original Kidde pump mfgt in 1952 to a 'new' design pump made in 1958. I paid $250 for the pump which I bought in the 'aircraft parts' section of EBAY. I cleaned the unit and straightened some cooling fins. I started to do a typical overhaul, basically removing the heads and barrels and checking the pistons, valves and springs. However, things looked so good that I stopped at cyls three and four and didn't bother to check 1 and 2. I had to build a new front support and add a 1/4 inch block under the drive adapter (outboard bearing mount) to make it fit. Fired it up and checked a few things. So far as I can tell performance is like new. Fills a '80' in 21 minutes.

The unit doesn't quite put out the rated 4 cfm because the engine is only rotating about 3150 rpm. If I could figure out how to change the linkage on the governor I might just go ahead and speed it up. No hurry, though.

A few years ago, I helped a friend locate a Bauer U-10 for a cheap price. The unit weighs about 110 pounds and is very reliable. However, when he told me the unit produced 4.2 cfm I started to feel a bit chagrined. The commercial guys had surpassed my little homemade! Subsequently, I found out that the Bauer company was blowing smoke. By careful reading of the definitions of 'SCFM' it became apparent that the Bauer which was rated 4.2 SCFM actually only produced 3.5 cfm actual free air or what USED TO be defined as SCFM. I felt better after that.

Is it ok if I call you Gramps? You built your first compressor before I was born!!

 

[pescador775]

Call me anything but don't call me late to supper.

 

[VaPadiDiver]

For those looking at buying a Portable, yet dependable compressor here is my story.

I bought an Alkin w31 about 2 months ago (June 2005). www.chesterdiveclub.com/compressor.htm I searched high and low. I looked at all the models out there. I looked at new ones, used one, military surplus... you name it. I bought an Alkin and I cannot be happier. It is a 3.5 cfm compressor that cost about $3000.00 +/-. As for portability, it weights about 119lbs. (electric) but it has wheels. I also have rigged up a 25' extention cord (220v single phase, not a regular cord - had an electrician make it ($30.00) which I attach to a gas generator. Generator is about 5000 watts, one I got at Home Depot for about $600.00 before hurricane Gaston a year ago. It works great. The compressor draws about 13 amps at startup and my generator barely feels it. 25' cord keeps the generator fumes away. 50' may be fine too. the longer the cord the harder the startup may be due to drop of electricity over distance.

I bought the compressor from Airetex. I also found that the staff at AireTex (Kay and Deigo.. hope I spelled that right) are Very nice and helpful. Great people to call and ask questions to. I did not feel like an idiot for asking questions most people buying a compresor should know. Also, this is the best part, I ordered it on a Friday from Texas, it arrived in Virginia Monday morning

I do have to recommend to anyone though, buy a storage bottle (444cf 4500 psi tank) or 2 or 3 of them. You will run your compressor a while to get them full but you will run it alot less to fill or top off tanks. This saves the internal parts of the compressor that bang around at the inital start-up (This happens on ALL HP compressors not just Alkin).

If anyone wants to see my setup via pictures or in person, please email me directly at contact@chesterdiveclub.com. I am 1/4 mile off of exit 54 on I-95 in Virginia (Lake Rawlings Area) Again, my opinion is non bias and this is not a publicity post for Alkin, just another diver giving his two cents.