Alright, I figured I'd ask the guys that are using them. I use my shop only for my own personal work but like to find projects of all sorts whether it be a little repianting or a bit of fab work, just something to do and to get me outa the house in the winter. I need one that is capable of running a paint gun, air chissel, impact wrench, blow gun, dy grinder, probably a pollishing wheel and would like to get something that could keep up with a DA sander (only ocasional use though so not a requirement). I'm looking for something in that $800 range and was hoping to get an 80 gal tank compressor. I have a 220 plug wired in for both air and a welder but I don't know anything about the compressors themselves. I also plan to plumb in all my air lines with multiple outlets and have both a permemant and temporay water seperater (one that is attached permanently right after the tank and the other with quick disconects so I can attach it where ever I may be working (nice for painting and sanding).

So give me the low down on compressors and any recommendations would be apprieciated with what to get, where to get it from and what brands/types not to get. and if some one would like to explain the single, two and three stage compressors I would apprieciate it alot.

Thanks

 

Can't go wrong with IR. If I was starting over again, I'd start with craigslist. You'll be able to find a good deal for sure...

good luck.

 

Get a single stage unit. Get a belt drive unit not a direct drive unit. Don't fall for the phony HP ratings on the motor. Get an ~1750 RPM motor.

In order to power air tools at their rated SCFM you can use the following
formula to find the estimated ACTUAL horsepower required:

SCFM x HPF x 1.1 = HP

HPF (Horse Power Factor) at tool rated pressure:
-----------------------
psi __HPF 1-stage__2-stage
-------------------------
40_____ .107_____---
60_____ .136_____.128
70_____ .148_____.138
90_____ .170_____.156
100_____ .179_____.164
120_____.196_____.178


1.1 is a factor used for figuring losses in the system.

single stage compressor: eg. 6 scfm @ 60 psi = 6 x .136 x 1.1 = .9 HP
----------------------------------------------------------------------

Actual Continuous duty motors have fairly well established current draw versus
voltage and HP ratings. The values below also have a "fudge factor" built in for
line-voltage variations. There is no "free lunch" when it comes to horsepower.
See the following table for some generic values:

Single Phase Alternating Current Motors Full Load Current in Amperes:
-----------------------------
HP_____ 115V_____ 230V
-----------------------------
1_____ 16_____ 8
1.5_____ 20_____ 10
2_____ 24_____ 12
3_____ 34_____ 17
5_____ 56_____ 28
7.5_____ 80_____ 40
10_____ 100_____ 50

The above values are from the National Electric Code and reflect their use in
calculating branch circuit requirements. Also notice 115V values are twice the
230V values.

The following values are taken from the catalog of a major manufacturer of high
efficiency industrial motors for compressors. They will more closely resemble
the values you should see on motors on high quality compressor units.

Single Phase Alternating Current Motors Full Load Current in Amperes:
---------------------------
HP_____ 115V_____230V
---------------------------
1_____ 16_____8
1.5_____ 20_____10
2_____ 24_____12
3_____ 32_____16
5_____ 42_____21
7.5_____ --_____33
10_____ --_____44

You can see that efficiencies increase as motor size/HP increases.

To make things more confusing some retail manufacturers seem to "calculate"
their SCFM ratings based on displacement and rpm. Commercial manufacturers
actually test their units or use tables supplied by the pump manufacturer based
on testing.

 

I can recomend the Ingersol Rand SS5L5 (5hp single stage on a 60gal vertical tank). It is roughly in your price range at $900. The compressor is rated at 100% duty cycle and IR recommends use of their synthetic oil for even more durability(I think they double the warranty also) I don't know about a DA sander but it will put up with two air ratchets and. two air drills while studding two snomobile tracks at the same time.

 

Thanks guys, Like I said you need to spoon feed it to me, lol. I only know what I'll be using it for, I know little more than that. I've looked at quite a few but I really don't know anything about them and other than what they have printed on them I have nothing else to go on.

What size Air line should I be plumbing in. 1/2" or 1"? and I've been debating whether to use copper or PVC schedule 80, I'm leaning towards the 1" PVC for the ease of installation.

 

Check out previous threads on air lines. PVC is a no-no. I have a Camp. Hausfield 5 hp with a 60 gal tank (vertical) that handles my needs..about the same as yours. Supposedly according to CH a 2 stage is better but priced a lot higher, my single stage works just fine. You might want to consider installing the AC outside, and with an automatic H2O drain.

 

Installing outside would be fine but I don't think I want to be sucking in -20* temp. air in the winter. I think The condensation alone would steer me away from that plus I'm sure just like a car starting the compressor in that cold of a temp would not be good. I'll look into the thread about air lines.

 

There are numerous threads here on air lines and a FAQ sticky thread at the top of the page with more info. PVC is an absolute No-No, no matter what "schedule" you use. Iron pipe is the best choice. Copper can not be used in some jurisdictions because of fire codes.

 

Yep, already read the FAQ, won't be using PVC. Copper will be what I'm using if thats the case; no worrry on the fire codes. So how about any sugestions on plumbing other than the obvious cleanouts, multiple ballvalves, lowpoints in line, water seperator, no inline oiling; anything else? I was thyinking 3/4" main with 1/2" drop points. my longest run will be about 60' but a total of about 120. I was also thinking of mounting the main pipe around the top of my shop since its the first place to warm up in the winter when I turn the heaters on or do you guys think it will get to hot up their, there 10' ceilings. Since I don't use the shop everyday I plan on dumping the air out of the tank at night when I'm done, is there any problem with this?

 

Sounds like you have done your homework. If I were you I would make a loop of pipe around my shop and slope ot to one end to drain the condensate. Also bring your drops out of the top of the loop to lessen the chance of water going down your drops.

Also, cool the air as much as possible before it goes into the receiver or shop. You can make an aftercooler with an old power steering cooler from an old car or other high pressure tube bundle. With an aftercooler about 60% of the moisture will condense in your receiver where you can drain it off.
Good luck
Steve

 

Check out that FAQ again, there are a bunch of links listed to the info you want. There are other threads also with more info.

 

Yep, lots of good stuff in the FAQ area. I do have one qustion that I really didn't see ansewered. I know a closed loop system is best but unfortunaly the shop that I'm in has a 9' garage door, and a tinned and insulated ceiling. I don't think I have enough room below my door springs (which are almost touching the ceiling tin) to feed pipe through. I would run it into the attic above the door but the attic is all blow in insulation and I am also a little of what the temp difference is between the inside of the shop and the attic may cause some unwanted charactoristics. Is there any major problem with having the compressor basically centered in the air line with both ends closed?

 

No problem with that or even having it at one end. Big shops and factories worry about such things. Slope your lines towards the ends so the moving air is trying to push the water along. Drain the drip legs at the ends of the lines frequently. Take your drip legs at the end off the bottom of the horizontal pipe. Your air outlets need to come off the top of the horizontal pipe. Make yourself an oiler like the one in my gallery for your air tools. Use regular air tool oil rather than anything else, -it is cheap enuf. Use the flexible hose to connect the compressor tank (receiver) to the air lines. Put a ball valve on the tank outlet. Install a coalescing filter at your output couplers to keep any water or "crud" out of the air hoses. 1/2 or 3/4" main line is quite adequate for a home shop.

 

3/4 inch mainline is good for up to about 30 cfm. 1/2 inch mainline is good for 15 cfm.

The idea is to keep the air velocity in the main headers below 30 feet per second, with 20 feet per second being a good goal. If the air flows too quickly, it can carry water and dirt past your drip legs. For takeoffs, you can use smaller piping since up to 40 or 50 fps is considered acceptable for branch lines.

The concept with "closing the loop" on the mainline is that you get 2x the flow capacity (and half the velocity) "for free" with a minimum of extra piping (the air can take two paths to each takeoff). But with 3/4 mainline and the kind of compressor you are talking about, you are well within the goal velocities without doing this, even for burst usage like HVLP and impact guns.

SInce you evidently live in North Dakota, you need to be aware that many air compressors do not like cold temperatures. Many manufacturers consider 40 degrees (F) to be "cold". A small heated "compressor room" or a crankcase heater fitted to the compressor pump might be especially needed for your situation.

 

Thanks again every one! I don't think I will have any problmes with having the 40* Temp for the compressor since it'll be inside the shop but what I was thinking about doing is encasing it with gapped overlapping panles and using some sound deading material on the walls of the case. Think of it as 4 L shaped corners that over lap each other to form a square but having a couple of inches gap between the over lapping panels to allow air to freely move in and out of the compressor box. with something simular for the roof; like having the edges of teh roof over lap the walls but have a couple inch gap between the over lap of the roof and the wall (horozontally) and have the roof elevated so it acutally has a gap between it and the walls (verticaly). This should allow heat to escape and fresh air to enter and keep the noise at a respectable level. I figure if worse comes to worse I can always mount a fan to the box to move fresh air into it but I don't anticipate needing one.