air compressor recommendation

I think that it is a meaningless number, the number that you need is

15.9 CFM.

I have a somewhat similar single stage compressor and I am happy with it.

i

>

>

Note that the 15.9 CFM is rated at 90PSI and the compressor is rated at 175PSI. You will lose CFM as the pressure goes up due to inefficacies of the pump. A two stage is much more efficient at higher pressures than a one stage.

Looks fairly good for the price.

I have one of these.

I found that in a web search, have no idea who the seller is. If you're in CA there's one on ebay. item number: 180081439138 Thank You, Randy

Remove 333 from email address to reply.

>>

>>

Looks very nice!

i

I've never seen a compressor rated that way, but I assume they mean that will a full tank (@175psi), and the compressor running, you can see a max CFM of 19. But as the tank runs down, the CMF will drop to the CFM of the compressor - 15.

All compressors with tanks work that way but nobody rates the short term burst you can get out of a filled tank that I've seen.

I've got a 24 gallon 5 CFM compressor (which I hear running even as I write this) and wish I had gone ahead and spent more money to get a 10+ cfm unit for those few higher volume tools I like to use.

I recently noticed that Lowes sells a 60 gallon, 7HP, 12 cfm oil lubricated unit for only $499. I don't know anything about it, but the price is very low for the quoted specs. Most in that range are over $800.

Buy 2x what you think you will need.

That should do it.

Steve

I recently traded up from a high end 120V compressor to a low end single stage 220V 15 amp compressor, 60 gal, rated 10.5 cfm at 90 psi tank pressure. I picked up the 220V unit for $450 off craigslist.

I find that the 220V compressor will run my dual action sander at 100% duty cycle, and a die grinder at 70% duty cycle. 70% does not sound ideal, but in practice, I don't run it 100% of the time anyway. You stop to look at your work, change sanding pads, etc, so 100% utilization is not something that happens much in the real world. The die grinder is the highest air usage in my shop, but I don't have a big air angle grinder, a sandblaster, or any big air tools.

The net is that I went from a very frustrating situation where I waited for my compressor a lot, to a situation where I just use my compressor and don't worry about running down the tank pressure. I don't think about my compressor anymore, which is great. I noticed a tool was not working right the other day, low pressure, and found that the compressor was turned off. ;-) I flipped the switch and went back to work without delay.

My take on it is simple, forget the 110V compressors, get a 220V compressor, and you will be happy. I don't think that you need an 80 gallon two stage compressor to be happy, although I would like to have one.

Richard

jeremy snipped-for-privacy@my-deja.com wrote:

Recommendation: Quincy.

For sandblasting get the option to allow the pump to free wheel (reduces #starts).

Wayne D.

Thanks for the replies. Have some more questions re: installation

Now after some research I think I am going to pay a little more and get the Ingersol Rand 2340L5 or 2340N5 (60 or 80 gallon). How many CFM can I expect @90 PSI, would it be almost double the CFM at

175PSI? Especially if effciency goes down with pressure?

What else do I need to get to use the compressor? I already have air hose, so I just need to get this regulator? Do I put this at the outlet of the tank, then to the reel?

What about the drain system.. I really don't like padcock valves so would I have space to ad an elbow and a ballvalve?

For the padding, I was going to use one of the exercise/anti fatique pads. Does this sounds ok?

Grainger sells a 240V hour meter for around $20 I believe. Does anyone know where to wire it in.

Can someone explain what does a Mag starter do and why is it good to have one, and why do only some compressors have it? the IR 2340 I think comes with a prewired starter but I am not sure if it has it for the for 230V 1 phase version

Finally will a 30 amp breaker work for the compressor (5HP). I was going to use 10 AWG wire because they are rated for 30 amps.. I read the IR document it said something like 6 or 8 AWG, I think it's too stiff to run into the breaker box.

Thanks!!

Not really.

I would get a filter/regulator combo to trap water.

Regular screw type valve works for me.

I use a piece of carpet, works fine.

To the motor/output of the starter switch.

magnetic starter uses an electromagnet to open and close main contacts.

That depends on the length of the wire.

If you are setting up a subpanel in your garage, it pays go get as big subpanel as possible.

i

Constant run unloader system. Normally used on gasoline engine driven compressors, but also useful where there is a constant use of air but the volume varies wildly minute to minute, like machine shops.

And it's doubly valuable in a commercial application where your power meter has a Demand Load factor. If you leave the compressor running, you don't have the 200% to 400% start surge every time the compressor motor starts. One start surge in the morning when nothing else is on.

The trick would be to design a compressor with an automatic change-over controller. So it will run in motor-start mode on nights and weekends when the air use is none or very slight, and switch to unloader mode when actively running tools.

-->--

If you would like to buy two, I'll take the extra one off your hands! I'll even give you my current 5 CFM unit!

I have no clue. But I doubt it. It seems reasonable to me that if a unit can push out 14.7 @ 175 it should be able to do 14.7 * 175 / 90 = 28.6 @

1. But I don't think it works that way. I think CFM might be converted to standard temp and presure to calcuate the cubic feet.

Here's another 5HP compressor for example:

PSI: 20.9 CFM @ 40 PSI/18.3 CFM @ 90 PSI

Note that cutting the PSI in half only slightly increases the CFM.

I suspect the IR unit will also only do slightly better at @90 psi than what it does at 175. Maybe something in the 18 CFM range like the unit above?

I checked there web site and their manuals for the fun of it and and was surprised they didn't give a CFM rating at 90 PSI since that's such a common benchmark for air compressors.

Hum. Most compressors come with a regulator built in. Maybe this one doesn't?

If you run hoses or pipes to a remote location in your shop, it's good to put a regulator near where you work to reduce the pressure drop effect that happens in a long hose when a high volume tool is used - or if you have multiple people using the system at the same time.

I have both a cheap air filter and an in-line oiler in my system. I have two taps - one before the oiler and one after so the tools that need oiling can be driven from the hose connected to the oiler and applications where you don't want oil (spay painting or blowing dust) doesn't have the oiler.

You don't need an oiler - you can just add drops of oil to the tools that need it from time to time.

This is a good question for people with air compressors. How often do you drain you compressor? Is there any way to set it up so you don't have to empty the tank first to drain the water?

The manuals all say you should do it every day. I don't. I do it once a month at best. I don't use my compressor that much and having to decompress it and drain it every time would be a bitch. But better than having it blow up on me from rust I guess. I leave it on full time so it's always ready for me to use. If I turned it on every time I wanted to use it, I would have to wait 5 minutes for it to get up to pressure, then use it, then spend 10 minutes decompressing down to 5 psi or so before I could open the drain valve.

What do the rest of you do? Am I taking too much of a safety risk by not draining it more often? Is there some way to set up a system to drain it without having to decompress it?

The IR manual says 8 AWG for 230 V 5HP for 50ft or less of run. But that seems to be a "sure to be safe" number. I would suspect that 10 AWG would work, but it would be best to consult an expert or simply find out what your local building codes require for a 5HP motor and for whatever distance you need to run the circuit.

Air piping must NOT be hard PVC plastic pipe. The main-line runs should be Copper, Black steel or Galvanized Steel only. Slope the runs down toward the far ends, and provide drip legs and drain c**ks to get rid of condensation.

(They do make a special green CPVC plastic pipe specifically for air lines, but it's ultra expensive stuff, meant for chemical plants.)

Important thing above - most of the time you do NOT want air with oil in it. If for no other reason than it gets on the inside of the hoses, and then you use that hose for painting and ruin the finish.

I never drain the air out of the system, just have a piece of hose attached to the drain to take it to a catch bucket. Crack the valve to drain the water, when the water stops and the air starts, close the valve.

If you start seeing a lot of oil in the catch-bucket water, you can get the compressor checked out.

If this is on the walls to damp the noise of the compressor, I used fire rated mineral-based acoustic ceiling tiles and construction adhesive. You do NOT want any foam that isn't fire retardant treated.

And when I finish the little closet around the compressor it will be acoustic tile over drywall on the inside, fiberglass insulation in the stud cavities, and drywall outside. Solid core door with acoustic tile on the inside. The refrigerated air dryer will sit on top.

Anywhere after the contactor or pressure switch, or right to the back of the motor.

Most pressure switches are only rated to switch 3 to 5 HP directly on the contacts. If you need to control more current, you need a big relay to do it.

A Magnetic Motor Starter is the big relay, and a current sensing overload section to cut off the motor in case of problems - a critical thing to have on three-phase motors, because loss of one phase will cause a no-start.

(And the most common cause is a blown fuse or half-tripped breaker, followed by one of the contacts inside the starter that has worn out or broken.)

The overload section reacts much faster than the circuit breaker. because the heaters are sized exactly to a known motor load.

Voltage Drop is your enemy here. 10-gauge and a 30-amp breaker will work fine, but unless you have a very short cable run #8 is cheap insurance.

Make sure the breaker is marked "HVAC-R" or "Motor Rated" to allow for the start surge - some older magnetic-only breakers will nuisance trip on the start surge.

-->--

Yes, good point. Once you use a hose for oil, you should never mix it up and use it for something else or you risk creating problems. I only have one hose connected after the oiler and I never intend to take it off or use it for something else. All my other hoses and air runs are oil-free.

I've been waiting to reply to your message until I could test this out. The manual for my compressor says you should lower the pressure in the tank to below 20 psi before opening the valve and I assumed it would be a disaster to try opening it at pressure (175 for my tank). But I just tested it starting low and working up to higher pressures and it works just fine. I thought it might be hard to open, or hard to close or hard to control the air escape with the value under pressure but it works just fine. Thanks for the suggestion. I'll be able to drain it far more often now.