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Professional Woodturner
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Discussion Starter #1 (Edited)
Hello Everyone,

It's been a while since I've been on this forum... As one of my friends likes to say: "Life sometimes gets in the way."

My trusty air compressor died a few days ago. It was about 16 years old and was a 5HP Coleman 2-stage electric with an 80 gallon ASME tank. I knew that "Ole Red" was getting long in the tooth, but I have never had any problems with it until recently.

A few weeks ago, it started loosing air overnight. In the morning the tank would be empty, but I could not find any apparent leaks. One day I was out with my dogs and I heard the exterior purge line hissing. The purge line allows the daily water accumulation to be sprayed outside periodically, making purging easier than using a bucket.

This lead me to believe that the valve on the bottom of the tank was blocked by a bit of rust. I removed the valve assembly on the bottom of the tank and examined it closely. Everything looked in a proper nick, so I turned my attention to the condition of the main tank.

Using a tiny (3/16" diameter) inspection camera, I examined the interior condition of the tank and found lots of rust. The bottom of the tank was in a sorry nick and I decided to scrap the compressor altogether instead of trying to replace the storage tank.

To get a better view of the interior condition of the tank, I decided to cut it into several pieces. What I found surprised me... The inside walls and the top of the tank were rusty, but still in a proper nick. The bottom had lost 65% of the wall thickness in some areas. :eek: Not a good thing to see in a tank that holds air at 175psi.

If you have an old compressor, you might want to drain all of the air out of it and inspect the tank interior. I used a tiny inspection camera that I bought last summer... It has been worth it's weight in gold and I've used it many times to diagnose machinery problems. Although I drained my tank several times a day, it still developed heavy rust in the bottom.

I'm glad I decided to scrap the compressor and I'm looking forward to getting a new 7.5hp, 2-stage, 80gal, compressor that features a sound deadening enclosure to reduce the overall noise to 69db. My old compressor was rated at 18CFM, my new one is rated at 25.5CFM.

The only problem with the new compressor is that it needs a 60amp breaker and a line that can handle it's 58amp startup and it's 32amp continuous draw. The old compressor ran on a 30amp breaker. I have had three electricians out and I will need to get a new sub-panel installed and run a #4 or #6 wire to the unit, at a cost of 1,340 Quid, ($2,000.00). :eek:

The compressor is 2,350 Quid ($3,500.00) delivered and when you tack on the cost for the new electric service, it starts to get bloody expensive. Who would have thought that the electric service cost would be more than half the cost of the compressor? I should have been an electrician... Cheers!
 

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Old School
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24,027 Posts
Over the years I never had a tank rust out...at least I didn't know about it. For the 80 gallon or 60 gallon tanks I never hooked up an automatic drain. I physically drained each day, and blew out the balance under pressure.

Two stage compressors for woodworking aren't worthwhile IMO, as a single stage works just fine. Electrical is simpler. Most all shop air tools run off 90PSI to 100PSI, so compressor output much beyond that is moot.

In a multi use shop, what can make an efficiency difference, is to run the airline piping in a loop around the shop, and reconnect at the tank. This will stabilize the line pressure. In most shops the airline piping is a dead end. It starts at the compressor and ends somewhere else, and QD's are tapped along the way.






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Professional Woodturner
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13 Posts
Discussion Starter #5
Old Habit

Why does someone from Texas present prices in "Quid?"

G
Hello,

I frequently write articles for a U.K. based woodturning magazine, so presenting currency in Quid (Pounds Sterling) is an old habit for me. I also showed the U.S. dollar equivalent, IIRC. Old habits are hard to break! :smile: Cheers mate!
 

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Professional Woodturner
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13 Posts
Discussion Starter #6
More Air...

Over the years I never had a tank rust out...at least I didn't know about it. For the 80 gallon or 60 gallon tanks I never hooked up an automatic drain. I physically drained each day, and blew out the balance under pressure.

Two stage compressors for woodworking aren't worthwhile IMO, as a single stage works just fine. Electrical is simpler. Most all shop air tools run off 90PSI to 100PSI, so compressor output much beyond that is moot.

.
Hello,

(Note: I turn for a living, so my needs are different from a hobby woodturner).

Like, you I manually drained my old 80-gallon compressor tank daily (several times a day in fact many times), but that was not good enough to prevent the bottom of the tank from becoming perished after 16+ years.

My new compressor is protected against rust on the inside and it also features a programmable automatic purge valve, so no more manual purges for this bloke. :thumbsup:

A two-stage compressor works best for my needs, so that's what I'm staying with on the new replacement. Getting the new electrical upgrades for the compressor sorted is a wee bit hard to swallow, but there it is...

My old two-stage compressor could not deliver enough air to run my sandblaster efficiently, but that will not be a problem with the new unit. The old compressor also had no sound deadening enclosure, which the new one does feature and effectively limits sound to 69db, whereas the old unit ran at 90 - 100db. :eek:

This feature alone makes the compressor a great upgrade in my studio, as the compressor sits 15 feet from my Oneway 2436-3 lathe. :yes: Cheers mate!
 
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