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Air compressor advice, please

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bash

bash

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I finally picked up a compressor last night at Sears - it is a 15 gallon 3hp peak (1.5hp running, I think) Craftsman, usually $200, reduced to $90 (floor model). I really wanted a bigger one, but for the price I couldn't say no. The problem is that it has no instruction manual, and the parts department either couldn't help or (more likely) couldn't be bothered to help with a replacement, so I would be grateful if you knowlegeable types could fill me in a bit!

I bought a 50ft 3/8" diameter hose - is that the right size to go for? The coiled types look too small, and I would think you would lose a lot of pressure?

There are two gauges, one says regulated and the other tank. I tried turning the knob between them but it doesn't seem to do anything... The needle on the regulated side stays the same as the tank side. I suspect that I am being an idiot - can anyone tell me how to regulate the pressure?

Any other tips would be most welcome too. I guess I won't be able to do any blasting with such a puny motor, but other than a ratchet and impact wrench, are there any great air tools I should be looking for?

Thanks as ever for your help!
Alistair
 
Not long ago, I bought a floor model pressure washer - just call Sears & tell them the model number of the air compressor & they'll send you all the books for a nominal fee (think mine were around $5)

If you plan on doing body work, go to Harbor Freight & get one of their little air sawzalls...& a grinder, and an orbital sander, &..............
 
Hi Bash, I have the same model. It's not bad, but I kind of wish I had bought a bigger one. The die grinder doesn't run very long before I have to let the compressor catch up. If you unscrew the knob (anti-clockwise, as the Brits would say), then the regulated pressure should go down. If it stays at the tank pressure, then I would say the regulator is broken. If you unscrew it completely, the regulated pressure should be at zero. A 3/8" hose works fine, and I can use the impact wrench, air ratchet, blow gun, paint sprayer, etc.. Oh, and since you didn't get the manuals, they did say you're supposed to do a "break in" of the compressor, which involves opening the drain valve, and running it for half an hour with the drain valve open. I don't think that will help the regulator situation though, if it is not regulating.
 
Some of the regulators are of the bleed type so you need to use some air after you turn the knob anticlockwise to see what the new set pressure is.

For parts and manuals, go to www.sears.com and follow the "PARTS" link on the left.
 
Regulator: Most are as Craig says and will not register a pressure drop until you release air from the line. However it should register a pressure increase, provided the regulated pressure is below the tank pressure when you turn the knob.

Air Hose: You did good. 5/8" is the most common size and will allow plenty of air volume. I suggest placing a shut-off valve directly onto the compressor followed by a female quick-connect fitting. I use a brass ball valve on mine from a hardware store. This will allow you to disconnect the hose from the compressor if you need to without tools and without losing pressure.

Also place a female quick-connect at the end of the hose so you can link two hoses together. Keeping two short hoses takes up less space and are easier to manage than one long hose. I typically keep one 25' and one 50' hose on hand. While in the garage use the shortest hose you need for faster response.

"Curly" hoses are not a good idea. They become brittle with age and eventually will explode, sending hard plastic bits hurling toward every eyeball in the room. If you need something that can get out of the way easier than a regular hose, consider a self-retracting air hose reel and mount it to the wall or ceiling. I recommend plumbing it seperately from any other lines. To do this, attach an air manifold to the wall near the compressor. A 3 from 1 should be plenty. and you can plug any unneeded ports. Run a short leader hose (short piece of regular air hose) from the compressor's quick connect to the manifold. This will allow you to disconnect and move the compressor when needed. You don't need a quick-connect on the "in" port of the manifold.

From there, connect the air reel directly to one of the "out" ports of the manifold. From another "out" port, you can either directly connect your 25' (or whatever length you have) air hose or use a quick-connect. Having the manifold allows a shorter run to the end of each hose rather than connecting one to the end of another.

Other tips:

Don't forget to use teflon tape on every air fitting connection to prevent leaks.

NEVER use PVC pipe to run air lines through the garage. They are not designed for this application and will eventually rupture - very dangerous! Use copper pipe only. Galvanized works but will eventually rust and send flakes into your air tools.

Drain the water from the tank after every extended use. The manuals typically say to do it once per day.

A water trap installed on the outgoing line somewhere between the tank and manifold will help keep your air dry. You can also make a water tap out of copper pipe and attach it to the wall near the manifold.

Keep the compressor turned off when not in use. A tiny air leak can cause it to turn on unexpectedly in the middle of the night and scare the bajezus out of you.
 
[ QUOTE ]
...NEVER use PVC pipe to run air lines through the garage. They are not designed for this application and will eventually rupture - very dangerous!

[/ QUOTE ]

Even schedule 80? 1/2 inch will take 850 psi. Even with a 3:1 ratio that would leave 280 plus psi of air pressure.
Bruce
 
It isn't the pressure, it's what happens over time. PVC will eventually stress and form cracks. If it's a burried line that's one thing. But running along a wall at eye level is another. It ain't worth it! But if I had to run PVC it would certainly be Schedule 80 before Schedule 40.
 
Thanks for the replies, guys. I will head back to Sears and see if I can find someone a bit more helpful in the parts department to get a manual, otherwise the website sounds like a good option. I think I need to do some more playing with the regulator to find out what I was doing wrong - at least I have an idea what is supposed to happen now!
Cheers
Alistair
 
I have not looked at the Sears website but I thought they hade manuals you could print off the web.
 
[ QUOTE ]
[ QUOTE ]
...NEVER use PVC pipe to run air lines through the garage. They are not designed for this application and will eventually rupture - very dangerous!

[/ QUOTE ]

Even schedule 80? 1/2 inch will take 850 psi. Even with a 3:1 ratio that would leave 280 plus psi of air pressure.
Bruce

[/ QUOTE ]

Glad you piped up Bruce, /ubbthreads/images/graemlins/thumbsup.gif I was just going to pass that one up.Even schedule 40 PVC is inexpensive and good for routing air around in the garage.---Keoke
 
The reason you should never, ever, EVER use PVC pipe of any kind for air lines is that when PVC fails it often fails in a catastrophic brittle fracture mode, i.e. shrapnel. Can you say pipe bomb?

Although schedule 40 and 80 can withstand the pressure when they’re in perfect condition in the real world there are too many ways to compromise the integrity of the plastic. The occasional bump, ding, nick, spilled chemical, mis-glued joint, etc that are all too common can spell disaster (as in major injury or death).

There are plastic tube systems for compressed air. They use plastics that fail in a tearing mode, splitting rather than shattering. They’re usually more expensive than copper pipe but much easier to install or reconfigure.

One should pay attention to details even when using copper pipe. If the wrong tube or solder is used or the joints not sweated completely the connections can fail. In a compressed air system that can send a fitting flying at high velocity. Here’s a table on types of copper tube and their appropriate uses. Here’s a table on pressure ratings of joints.

Modern polyurethane “curly” hoses are fine. They won’t get brittle. Just choose one with a large enough ID and not absurdly long. Depending on the tool it can be very handy to have a few feet of coil at the end of a long run of straight hose.


PC.
 
Yeah PC, I wonder about the DIY glued joints other than that overhead routed systems seem to be fine.Of course if you do not know how to properly sweat a copper joint you can be in the same fix.---Keoke
 
All bombs seem fine, …until they go off.

With a poorly sweated joint you have one part going in one direction, albeit a heavy part. Or you might have two long runs separate and release air but not go flying.

PVC shatters, sending shards everywhere. It’s not a common event but I’d rather it be an impossible event than an unlikely one. Overhead is the last place I’d want a bomb going off around me.


PC
 
Yep, even with a PVC setup... I'd want it outside (though sheilded from the sun 24/7), with just the connect points coming inside (and barely at that).

This said.... unless I needed more than 2 or 3 stations running at the same time, I'd have to go with a semi-portable compressor/tank unit that I could move to where ever I needed it at the moment.
 
Here's some Bulletins from OSHA concerning the use of PVC compressed air piping. They mention an incident where there was a PVC pipe buried three feet in the ground that blew up and made a crater four feet by three feet.
 
Even Concorde and NASA experience failures... Schedule 80 would likely last long enuff to make YOU the DPO... "BlackPipe" would carry it to the SDPO (Second DPO) level.

Breathing or getting out of bed in the morning are hazardous... pick yer battles, hedge yer bets. Build the system you feel can serve the purpose.
 
/ubbthreads/images/graemlins/iagree.gif

And there are Darwin Awards for those who make a conscious effort not to let their health get in the way of meeting their maker soon....
 
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