Air Compressor Size

[Steve Braverman]

My air compressor is probably over 50 years old, so when I found the bottom of the tank rotted through, I wasn't too surprised. It's a big unit with an 80 gallon tank. Besides air tools, I also have a small blast cabinet and a canister sandblaster. Do I need such a big compressor?

[Matt Harwood]

Bigger is always better when it comes to air compressors. If you've had a big one, you will not be satisfied with a smaller one, especially running a blast cabinet and sandblaster.

[Bloo]

52 minutes ago, Steve Braverman said:

Do I need such a big compressor?

Yes.

 

40 minutes ago, Matt Harwood said:

Bigger is always better when it comes to air compressors. If you've had a big one, you will not be satisfied with a smaller one, especially running a blast cabinet and sandblaster.

 

This^^. "I wish I had bought the compressor one size smaller" said no one, ever.

 

[ILIKECARS53]

I agree with Matt and Bloo.  Had an 80 gal  6 1/2 hp 2 stage air compressor but sold it with the house when I moved from NJ to PA.  Thought I could get away with a smaller 60 gal 3 hp unit.  Wrong.  Saving up for another 80 gal 2 stage.

[TTR]

First, the size of the tank or HP rating are not important or intelligent considerations when looking to buy or upgrade an air compressor.

They’re merely marketing gimmicks to hoodwink consumers, just like with many other consumer products, including cars.

How many new car buyers are enamored by and excitedly recite (higher ?) HP numbers of their vehicle, without even understanding what, if anything, it actually does or means for them in practice.

 

Second, OP indicates the “tank rotted trough”, but makes no mention of condition or size of the air compressor itself or the motor, which, especially the pump, are more important part of the entire equation than the tank.

If these “over 50 years old” components are in reasonably good condition and serviceable, depending on their brand and construction, their overall quality might be far better than anything new (Chinisium crap) one can buy for less than $3000-$4000, so another option is to service the pump + the motor and just replace the tank (& remember to drain it more frequently to prevent rotting).

Edited June 11, 2022 by TTR (see edit history)

[TTR]

P.S. To determine whether an air compressor is adequate for expected performance, let's say using it for a media blasting or power tools, look for its output, i.e. CFM rating (not “GPM” rating, as I initially posted under significant influence of adult beverages).

 

Depending on type of equipment, materials and operating pressure (60-90+ psi ?), media blasting usually requires at least 15+ CFM compressor output, but to play it safe,  I would recommend 17+ CFM, as most hobbyist will likely not need much more. Most air tools use about 12-15 CFM (@90 psi).

 

One can have the largest tank in the world, but if the air pump (= compressor) cannot keep up, maintain or surpass extended usage, the tank (= reservoir) pressure will eventually become low or even empty during use and then, depending on the air pumps output, it might take a long time refill it back to useful pressure again.

 

 

Edited July 17, 2022 by TTR (see edit history)

[Ben Bruce aka First Born]

I thought it is CFM.

 

  Ben

Edited June 12, 2022 by Ben Bruce aka First Born (see edit history)

[TTR]

10 hours ago, Ben Bruce aka First Born said:

I thought it is CFM.

 

  Ben

You’re absolutely right Ben. 👍

Too much Tequila, Whiskey and Wine, not to mention a great Cigar …

… and couple of Wheat Beers tonight for this old cowboy ?

 

Fixed now.

Edited June 12, 2022 by TTR (see edit history)

[Steve Braverman]

On 6/11/2022 at 12:50 AM, TTR said:

 

Second, OP indicates the “tank rotted trough”, but makes no mention of condition or size of the air compressor itself or the motor, which, especially the pump, are more important part of the entire equation than the tank.

 

If these “over 50 years old” components are in reasonably good condition and serviceable, depending on their brand and construction, their overall quality might be far better than anything new (Chinisium crap) one can buy for less than $3000-$4000, so another option is to service the pump + the motor and just replace the tank (& remember to drain it more frequently to prevent rotting).

I think the motor and pump are fine. I've looked into a new replacement tank, and the cost is about the same as a new compressor. Even though I think they're fine, a new compressor will probably be much better, even if it is chinesium. 

 

Tractor Supply has the same size compressor, and it just went on sale. I think I'll pick it up, and hopefully it will outlive me. I will be sure to drain the tank more often!

 

https://www.tractorsupply.com/tsc/product/ingersoll-rand-80-gallon-5-hp-reciprocating-air-compressor?cm_vc=-10011

Edited June 13, 2022 by Steve Braverman (see edit history)

[TTR]

Looks like a fairly reasonable package for home/hobbyist use (+ IR has some experience building compressors and at least claim this one being US made 👍). 

Only other thing I would check (since there’s no mention of it) is the RPM it’s designed/intended to run at, i.e. +/-1750 or +/-3450. 
For variety of reasons, slower RPM would be preferable.

I’ve been thinking of getting one for our garage at home and might look into one of these.

 

Edited June 13, 2022 by TTR (see edit history)

[Steve Braverman]

I went to TSC to look at the Ingersoll Rand compressors. They have a huge decal on them the says, "Made in USA," and in smaller type, "from global components." The pump is made in India. My old compressor is a Saylor-Beall. I looked it up, and it's a $3-4k unit new. Now I'm undecided between buying a new tank and restoring my old compressor, or just buying the new one. In all fairness, the new IR will probably last me forever.

[TTR]

23 hours ago, Steve Braverman said:

I went to TSC to look at the Ingersoll Rand compressors. They have a huge decal on them the says, "Made in USA," and in smaller type, "from global components." The pump is made in India. My old compressor is a Saylor-Beall. I looked it up, and it's a $3-4k unit new. Now I'm undecided between buying a new tank and restoring my old compressor, or just buying the new one. In all fairness, the new IR will probably last me forever.

Thank you Mr. B., for taking time with the follow up on this topic, including discovery and revealing some sad realities related to manufacturing/marketing claims and the pause(?) they gave you.  

Seems like you're on the path to informed/intelligent decision making. Good luck with whichever you reach. 👍

 

 

P.S. As a side note, my first compressor which I bought from an estate sale of a friends FIL over 30 years ago was a used, probably 40-50(?) y.o. (at the time) smaller 2-stage (originally 15-17 CFM ?) IR that looked like it had always been stored outdoors and if I recall correctly, in fact behind my friends FILs a small body shop.

I also bought a tool box full of old body work tool + other equipment, all for full, but reasonable asking price (IIRC, compressor was "valued" by the estate at around $300.-). 

 

Anyway, I hauled the compressor (along with everything else) to my newly established (restoration) shop, cleaned + fully serviced it (& made a few small upgrades) and put it to work, which it did well for following 20+ years, until less than 10 years ago, I unexpectedly saw a year old (=like new), bigger/stronger, 2-stage IR (24 CFM) combo displayed for sale in front of some shop that was closing 1/2-mile down the street from me. They were asking $1400.-, I offered $1000.- (in cash) which they promptly accepted (later research and paperwork they gave me revealed a price of new one was around $4500.-). 

After basic service of the new one and switching it to use, I rolled the old one to the curb with a "For Sale" sign (incl. $750.- price) on it and sold it couple of hours later to someone driving by. He offered and paid $650.- after we rolled it back to my shop and plugged it in for proof of its working condition. 

 

I don't really expect having to buy another one for the shop for the rest of my life, but have been on the lookout for one to put in (or behind) the garage at home, especially now after my wife retired and I turned part of it into her arts/crafts/gardening shop (she just hosted a miniature mosaics/tiling craft party last Saturday and all her friends were allegedly envious of the work space I had recently created and equipped for her).

Edited June 15, 2022 by TTR (see edit history)

[ILIKECARS53]

Tractor Supply IR compressors ........   Please read the reviews.  There are many complaints about the motors.

[TTR]

On 6/17/2022 at 4:00 AM, ILIKECARS53 said:

Tractor Supply IR compressors ........   Please read the reviews.  There are many complaints about the motors.

Good point, since the overall quality of any equipment is the sum of the quality of its components/parts.

 

OTOH, I rarely read product reviews of anything due to knowing reviewers qualifications.
I prefer to use my own critical thinking coupled with common sense and logic instead.

 

To use air compressors for example: A good quality 2-stage air pump delivering sufficient amount of air commonly needed for automotive restoration related equipment, tools and work will probably costs $1000.- to $2000.-at minimum, a quality electric motor probably at least +/-$1000.- and a well built (& safe) tank at least $+/- $1000.-.

 

So, if using above (estimated) figures, how good can a less than $2000.- compressor combo really be, let alone one for less than $1000.- ?

 

YMMV.

Edited June 19, 2022 by TTR (see edit history)

[Restorer32]

We run a 15 hp compressor in our shop.  Plenty of air but very expensive and noisy. It really makes the electric meter spin!

[Guest]

 An air compressor should be rated for the amount of air (CFM @ pressure that you need) Not the size of the air tank.

 

If your compressor does not supply that amount of air, you will need a larger tank in order to store enough air to use it for a short amount of time. Then you will have to wait until the tank fills up again.

 

 The better air compressors run at lower RPM's not 3400rpm's.

 

 Ps, I have a new 30 hp screw compressor, But, I still keep my 75 year old 20 hp compressor as a back up. Still works fine.

[Avanti Bill]

Make sure whatever you buy the motor is a 1750 RPM not 3450.  Air compressor companies Gin up the ratings of 3450 motors to try to make there HP higher for advertising and they don't hold up.  The Ingersoll Rand brand make some good industrial compressors but they also license their name to others who make really cheap compressors that don't last.  I recommend Champion as being a good value with a 1750 RPM motor and an 80 gallon tank most hobby shops would be fine with a 5 HP.

[Steve Braverman]

I bought the IR compressor from Tractor Supply, and so far i'm happy with it. I know it's not of the same quality as the unit it replaced, but it's new, it's quieter, and it doesn't leak. For those that asked, it runs at 1750 rpm.

[R Walling]

Steve Braverman

 I recently bought a new compressor and I keep my old one connected as a back up. It is 75 years old and will supply my 4 man shop, including my large sandblaster. Just because it is old, that doesn't mean it is no good.

 My advice is to buy a new tank if your old one will supply your shop with a constant supply of 90 lbs. air.

[Swear57]

I have a friend that his compressor locked up last fall. About 50 years old. I went to help him remove it.  Heavy that thing was heavy. The tank was 6 feet long. He bought an IR and has had nothing but problems. They have warranted it. Got to put in twice.

[Avanti Bill]

10 hours ago, Swear57 said:

I have a friend that his compressor locked up last fall. About 50 years old. I went to help him remove it.  Heavy that thing was heavy. The tank was 6 feet long. He bought an IR and has had nothing but problems. They have warranted it. Got to put in twice.

Most of the cheap IR's are foreign made and are junk.  They just pay a fee to use the name. 

Edited February 8, 2023 by Avanti Bill (see edit history)

[Turbinator]

My current rig is a Quincy 5HP, 60 gallon tank, and 15 CFM. I added an IR refrigerated line dryer and 80 gallon dry air tank reservoir.

I wish I had at least a 7.5 HP compressor and a larger line dryer., 29-35.

I media blast metal parts and powder coat.

[TAKerry]

2018-05-17_02-52-47 by Kerry Grubb, on Flickr

I walked into lowes a couple of years ago and they had this on clearance. Half off the sticker price. I ended up putting it in my new shop. Its a 60 gal. same size I have in my garage. Just a cheap unit but does the job just fine. My wood shop takes priority over mechanical stuff (as thats how I make a living, LOL) and I use mostly electric tools. But I can media blast with this one, and painting a car is no problem. Figured for the price if it lasted a couple years I would be ok. Going on 4 or 5 now and no problems.

[Turbinator]

On 7/28/2023 at 8:34 AM, TAKerry said:

Going on 4 or 5 now and no problems.

Happy to know the rig suits you.

I wish ID PURCHASED at least a rig with 25 cfm. My current bladt cab has a 15.1 cfm Quincy with 60 gallon wet air tank IR refriger line drier and 80 gallon dry air reservoir tank.

i recently bought a pressurized tank blaster ive had nothing but trouble. The problems may be very well my own fault. Im not certain whose fault but the company support line is pretty good. I think the problems will be solved.

[zmcdonal]

I snagged an 80 gallon snap on with super low hours from Facebook marketplace. Unfortunately it's been getting dusty in the corner of the garage waiting for some free time to wire up a sub panel for it. 

[Dandy Dave]

On 6/11/2022 at 12:50 AM, TTR said:

 (& remember to drain it more frequently to prevent rotting).

I took out the standard drain valve and replaced it with a ball valve early on in my compressor. I do it more often as it is much easier to deal with that the threaded radiator drain type. 

[Turbinator]

Gents, I do a lot of auto rusted parts resto. I need to blast and need production. Im not trained in any of this, BUT this my 3rd rig in 7 years. My first two media blast rigs were lame. I bought a 120 gallon tank with 10 HP 38 CFM COUPLEd with its 53 CFM 10 hp refridgerated line dryer. I bought a Texas Blaster pressurized media tank

The pic shows set up and testing status.. im not home yet as my automated electronic drain not work.

ill get er done.

 

[Turbinator]

On 6/11/2022 at 7:45 PM, TTR said:

would recommend 17+ CFM, as most hobbyist will likely not need much more. Most air tools use about 12-15 CFM (@90 psi).

TTR, I have no problem with your vision, explanation, and basis for your good presentation. AFTER appropriate and certainly accurate consideration for what you want/need/budget is nailed down. How you are going to separate water/condensate in your lines is paramount for a successful operation? If you know how to build a system of lines, traps, and separators AND. You eliminate moisture then that is first rate.

i decided on a refrigerated line dryer. Hobbyist, semi pro, pro metal finisher you want the thing to give you production. And I wanted production for my little metal finishing business. I could maybe/probably got by with s 7.5 hp 80 gallon tank 25 CFM OR greater. For me getting the moisture out of the lines was just as important as the rest of the variables.

Lator Gator

The Turbinator

Edited April 13 by Turbinator (see edit history)

[Turbinator]

On 1/29/2024 at 11:41 AM, Dandy Dave said:

do it more often as it is much easier to deal with that the threaded radiator drain type. 

You Sir, have that right! But, ive been told to get my air dry Ive got to run for 3 minutes and drain for 2 seconds. Honestly, I did not know the tank had to be that dry to get the air that dry before  the air went through refridgerated line dryer. I am not a patient man when Im media blasting, turbine wheel covers, Buick Roadwheels, headliner trim pieces, valve covers, brackets that go in the engine bay, whatever else someone wants.

My last blasting set up I had an 80 gallon reservoir tank of dry air, which I might put back in service if I don't get get the existing rig set up to suit me. Im not a trained metal/ fabricator/ welder just a fellow that likes rescuing old parts that can have another life. Here is a pick of an old Buick Roadwheel I cleaned up.

 

[TTR]

On 4/12/2024 at 10:51 PM, Turbinator said:

TTR, I have no problem with your vision, explanation, and basis for your good presentation. AFTER appropriate and certainly accurate consideration for what you want/need/budget is nailed down. How you are going to separate water/condensate in your lines is paramount for a successful operation? If you know how to build a system of lines, traps, and separators AND. You eliminate moisture then that is first rate.

i decided on a refrigerated line dryer. Hobbyist, semi pro, pro metal finisher you want the thing to give you production. And I wanted production for my little metal finishing business. I could maybe/probably got by with s 7.5 hp 80 gallon tank 25 CFM OR greater. For me getting the moisture out of the lines was just as important as the rest of the variables.

Lator Gator

The Turbinator

I agree about good moisture separation being a very important part of compressed air delivery system.

I designed and built delivery infrastructure for my shop facility comprising two separate units with about 8-10 outlets in each unit and each outlet featuring its own moisture trap w/drain over 30 years ago.

Fortunately for me, I’m located in low humidity inland Southern California desert like dry climate, so in 30+ years of almost daily use of compressed air for variety of tasks, from air tools & media blasting to painting, etc, I can’t recall having ever experienced noticeable moisture concerns or problems with my system.

[Turbinator]

12 hours ago, TTR said:

can’t recall having ever experienced noticeable moisture concerns or problems with my system.

You are knowledgeable, experienced, and lucky. I live in Maryland where humidity is miserable. Couple high humidity with being self taught Id be more comfortable throwing myself on rusty razor ribbon. 
The folks at Eaton told me to set the electronic drain opener on my compressor of 2 seconds on 3 minutes off. I just got a replacement drain opener today.

Ive grown to be patient and work toward real productivity. Ive had no real production with the media blaster for lack of knowledge and maybe common sense. The last rig i had was a Quincy 5 hp 15 CFM with IR 15 cfm refridgerated line dryer was ok but real slow. I burned up the 5 HP Baldor motor on the Quincy. Bought too much equipment for my real needs, again and not so economical purchase.

I bought a Texas Blaster pressurized tank system that works pretty good.

Reason I brought up moisture is it plagues me in my work.

So, ill use chemicals, 37% concentrate hydrochloric acid, commercial strip products, sanding, and media blasting to get my work piece clean.

Im a low production rare Buick parts refinisher for bright work, brackets, etc. i send out for chrome to N.Hollywood or Tucson. Others I powder coat at my shop.

Thanks for your input. With your permission Id like to write in on the nuance of media blasting.

 

[Turbinator]

Keeping compressor air pressure constant has been hard for me to maintain. I was wondering if the pipe length and routing scheme of the piping has any bearing on pressure consistency?. Thank you

[Larry Schramm]

15 hours ago, Turbinator said:

Keeping compressor air pressure constant has been hard for me to maintain. I was wondering if the pipe length and routing scheme of the piping has any bearing on pressure consistency?. Thank you

 

Short answer, yes along with the diameter of the pipes/hoses.  More 90deg turns, smaller diameter pipe/hoses the less available air at the nozzle compared to the air pressure at the compressor.

Edited Sunday at 11:32 PM by Larry Schramm (see edit history)

[Turbinator]

1 hour ago, Larry Schramm said:

Short answer, yes along with the diameter of the pipes/hoses.  More 90deg turns smaller diameter pipe/hoses the less available air at the nozzle compared to the air pressure at the compressor

Thank you. I appreciate your input.

I plumbed it myself and it shows. My compressor outlet is one inch. I moved down to 3/4”. Since I view my layout as temporary any change can only make it better. I checked and rechecked for leaks. Im clear there. Maybe a valve or some place not functioning right?