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mitchntx 02-10-2018 02:14 PM

Air compressor woes
 
For the last few months I've been noticing my 20 year old air compressor seems to be a bit sluggish. Takes forever to recover and cycles on really quickly.

During the cold snap in december, I had a drain line freeze and bust. As with my luck, it was on the pressure side of the ball valve. I don;t know how long it had run with a minor air leak. Changed the oil while I was in it.

Got that fixed and noted the cut-off air pressure was 135psi. :eek2:
Adjusted the cut-off and recover pressures. to 120 and 85.

A few days ago, I was headed to work and heard an awful screeching noise from the shop. Ran to the breaker box and killed the compressor. Great ... compressor is toast. :giveup:

I looked on-line and it would take $12-1500 to replace it. :headbang:

I checked the oil. It was clear and clean.
I removed the belt and spun the motor up. It ran smooth.
I spun the flywheel. It was free and easy to move. I could hear the compression stroke and the puff of air.

Only thing left is the switch, cut-off assembly. That would attribute the sluggish recovery which was actually over-pressurization.

The switch arrived today. I had to cobble a few lines and fittings together as it wasn't like for like. Wiring was different and was just one trip to the hardware store for a new relief valve and some compression ferrules.

Seems to work as before. But as a precaution, I'll probably leave the compressor breaker shut off till I can spend a day out there and have a chance to cycle the compressor a few times.

Best I can surmise is that the screeching I was hearing was either the belt slipping on the flywheel straining against the high pressure or the bearings inside the compressor itself for the same reason.

I don't hear it now, thanks goodness.

Cagiva 549 02-10-2018 02:35 PM

Re: Air compressor woes
 
Probly belt slipping , no shop tools are powered up when I'm not in my shop . That makes it too easy for a major screwup . My beer fridge is the only thing left on .

OldTLSDoug 02-10-2018 04:01 PM

Re: Air compressor woes
 
Mitch, glad you got it sorted. I used to turn mine off, it doesn't cycle much unless I am using the bike lifts.

rpcraft 02-10-2018 04:16 PM

Re: Air compressor woes
 
I'm on the verge of buying a new unit. I've been following along the new scroll compressor that Eastwood has out. supposed to be really quiet and very efficient. I think around 12 CFM @ 40 and 90 PSI with a max of 145 PSI. I've seen some bigger units that go up to 175 and a little more CFM rating down low but they are usually two stage setups and noisy as heck. My friend down around Killeen has one setup and after running it and letting it cycle he recorded it at 66 db when pressuring up and even though its only got a 30 gallon tank he says the recover time is next to nothing.

Decisions, decisions....

Texas T 02-10-2018 04:21 PM

Re: Air compressor woes
 
Quote:

Originally Posted by rpcraft (Post 1543527)
I've been following along the new scroll compressor that Eastwood has out. supposed to be really quiet and very efficient.

The scroll compressors seem to be what is being used on all the modern muscle cars these days, and my roots style 6-71 blower just sits in the garage collecting dust.

mitchntx 02-10-2018 06:43 PM

Re: Air compressor woes
 
Hadn't lost a psi since 1400 ...

Pros and cons to adding capacity ...

If I tapped in a 60 gallon tank or another 80 gallon, would I be asking too much of the single stage compressor?

rpcraft 02-11-2018 05:44 AM

Re: Air compressor woes
 
Quote:

Originally Posted by mitchntx (Post 1543554)
Hadn't lost a psi since 1400 ...

Pros and cons to adding capacity ...

If I tapped in a 60 gallon tank or another 80 gallon, would I be asking too much of the single stage compressor?

What HP rating and CFM rating on the unit?

maximus_flavius 02-11-2018 06:43 AM

Re: Air compressor woes
 
Quote:

Originally Posted by mitchntx (Post 1543554)
Hadn't lost a psi since 1400 ...

Pros and cons to adding capacity ...

If I tapped in a 60 gallon tank or another 80 gallon, would I be asking too much of the single stage compressor?

WMC must go thru a lot of air.......

txbanditrydr 02-11-2018 08:36 AM

Re: Air compressor woes
 
My Ingersoll-Rand 60 gallon has a single stage pump and does just fine. I wouldn't think the increase in tank size would matter that much providing you have an oil-filled cast iron pump unit.

I second a loose belt causing the noise.

mitchntx 02-11-2018 09:27 AM

Re: Air compressor woes
 
Quote:

Originally Posted by maximus_flavius (Post 1543605)
WMC must go thru a lot of air.......

Mostly hot ...


Years ago I had an oil-less 30 gallon compressor that I had daisy chained two 6-gallon portable tanks with standard shop quick connects.

Added capacity was great when rotating tires and such and it was very handy to always have a fully charged portable air tank to use.

The compressor never failed, but it ran a LONG time in the process of recovering. But to offset that, it ran half as often.

While troubleshooting my compressor, I was just wondering if I could do it on a larger scale.

Once the sleet stops, I'll pull the specs off the compressor and post them.

rpcraft 02-11-2018 03:54 PM

Re: Air compressor woes
 
I have one of the HF 25 pieces of trash hooked to a propane tank (I bought it clean and empty so don't fret fellas). I can't recall if it is 100 lb or 150 pound but its probably about 30 gallons total. I'm sure it's led to the early demise of that HF Unit. It's leaking air somewhere and right now I'm not doing anything with it to care but I figure once the new house is finished I am maybe repurpose the spare tank as a portable air tank.

mitchntx 02-11-2018 04:11 PM

Re: Air compressor woes
 
Quote:

Originally Posted by mitchntx (Post 1543615)
Once the sleet stops, I'll pull the specs off the compressor and post them.

3 horse
11.5 SCFM @ 40 PSI
10.2 SCFM @ 90 PSI

Thrasherg 02-11-2018 04:36 PM

Re: Air compressor woes
 
Well itís a lot better than my 20 year old Sears Roebuck compressor, it is only rated at 9.1 scfm at 40 psi and 7.1 scfm at 90 psi, doesnít say the power of the motor, but states 120 volts and 15 amps, which would make it about 2hp. Would love to get a bigger twin stage, but donít use it enough to justify the expense. If it ever goes bang, the replacement will definitely be bigger. No idea what size the tank is, about 3 feet long and 14 inches diameter.

Gary

humanrace 02-11-2018 07:19 PM

Re: Air compressor woes
 
I have a Jacuzzi compressor that I bought used in the mid '70s. It's one that runs constantly if it has electrical power. I think the device that stops compression is called a constant speed unloader. It came with about a 5 gallon tank and I now have it on a 60 gallon tank. In the old days, the service stations used a very small single cylinder compressor for a very large tank to operate their car lifts. Duty cycle is the key.

dukey33 02-11-2018 07:44 PM

Re: Air compressor woes
 
Duty cycle is the key.
If the comp and motor are rated for continuous duty cycle, theoretically they can be used to fill any size tank(s) or even direct output to a tool.

rpcraft 02-11-2018 09:06 PM

Re: Air compressor woes
 
Quote:

Originally Posted by mitchntx (Post 1543693)
3 horse
11.5 SCFM @ 40 PSI
10.2 SCFM @ 90 PSI

I think you will be fine with those spec's

humanrace 02-12-2018 10:38 AM

Re: Air compressor woes
 
A 60 gallon tank holds 60 gallons at atmosphere pressure (15 PSIA), about 400 gallons at 85 PSIG (100 PSIA) and about 540 gallons at 120 PSIG (135 PSIA). If my approximations are correct, it should take a 10 CFM pump about 14 minutes to go from 85 PSIG to 120 PSIG.

The Big Spank Daddy 02-12-2018 02:55 PM

Re: Air compressor woes
 
I have 2 60 gallon single stage (?) compressors linked together. Both are about 20 years old. One a Porter-Cable bought at Lowes the other a Devilbiss. One is 7hp the other 6.5. They are both twin cylinder and could be 2 stage, possibly ported inside the head, but I doubt it. They are linked via air lines but can run separately electrically. I typically just run one at a time, but use both tanks. The volume is the key as far as I'm concerned. With just one running it doesn't cycle as often, but yes it will run longer to get the 120 gallons full. If I'm really using a lot of air like blowing something off Ill run both at the same time. They are both rated around 12cfm. I paid like $300 for the porter-Cable at Lowes. I inherited the Devilbiss.

humanrace 02-12-2018 07:23 PM

Re: Air compressor woes
 
You can easily tell if they are 2 stage. One cylinder will nearly always be larger than the other. Also, the tube connecting the cylinders will have cooling fins and only one of the cylinders has an air cleaner.

OldTLSDoug 02-13-2018 05:07 AM

Re: Air compressor woes
 
When I was purchasing my compressor it was agony to decide what to buy. Ended up with a 3 cylinder single stage Husky from Home Depot. Like I said, if I am not blowing stuff and just using lifts it barely runs. I isolate my lifts since they both ooze a little air at times.

http://photos.imageevent.com/tlsdoug...20_1008511.jpg

http://photos.imageevent.com/tlsdoug...01_1350351.jpg


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