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KiddZimaHater
04-21-2012, 12:36 PM
I need expert advice on Compressors.
I'm in the market for a shop compressor, and don't know which brand to buy.
I need at least 6 CFM's at 90 PSI to run my die grinders.
And I'd like to get a large one with a 60 or 80 gallon tank.
Kobalt (Lowe's) has received bad reviews.
There's also Campbell-Hausfeld, Husky (Home Depot), Craftsman, Dewalt, Horror Freight, etc.
So many brands to choose from.
What do you guys recommend? And how dependable have your compressors been?

EddyCurr
04-21-2012, 02:36 PM
Some additional brands to consider

DV (aka Devair and Devilbiss)
Ingersoll Rand
Speedaire
Quincy

If you are interested in validating your anticipated CFM consumption, take
a look at pages 9-10 here:


Information Bulletin IFB-01 (http://www.centrair.ca/brochures/Infobook.pdf)
March 2007
Devair

"This booklet is primarily geared to assist both Distributors and
Customers in determining air demands in a shop, and designing
a compressed air system to suit."


Some other resources:

How to Choose the Right Air Compressor (http://www.jennyproductsinc.com/howtochoose.html)

Evaluating True Horsepower and CFM Ratings of Air Compressors (http://www.truetex.com/aircompressors.htm)

Rating of Air Compressors and Air Equipment (http://www.engineeringtoolbox.com/rating-air-compressors-d_848.html)

Time spent looking at commercial and industrial quality compressors can
provide insight that is useful in evaluating consumer grade equipment.

.

EddyCurr
04-21-2012, 02:42 PM
Ingersoll's booklet


Reciprocating Single and Two-Stage AIr Compressors (http://fileserver.ingersollrand.com/DocumentLibrary/Overall%20Recip%20Compressor%20Brochure.pdf)

.

lynnl
04-21-2012, 03:03 PM
I have a Campbell-Hausfeld, Medallion Series "Professional" (no less) from Home Depot, that's been running fine for at least 15 years now.

It's the 30gal tank. It claims 9.1CFM @90 psi and 11.5 @ 40.

Robo
04-21-2012, 07:28 PM
I'm not sure 6 cfm is large enough to run a die grinder they are air hogs! Typically a 5 hp 2 stage air compressor producing app. 18 cfm will run quite abit using a typical die grinder. Just fyi....

sasquatch
04-21-2012, 08:09 PM
The die grinders i've seen require around 4-5 cfm.

Boucher
04-21-2012, 08:27 PM
I bought a single stage 5HP IR from tractor supply several years ago. I would not do that again. I have a bead blast cabinet that is my largest demand. About 15 years ago I bought a Senco twin tank two stage wheelbarrow type compressor that worked very good. If you have a fairly large tank a small compressor will meet most usage demands. Even with the blast cabinet the actual duty cycle is not that continuous.

sasquatch
04-21-2012, 08:56 PM
A large storage capacity is good, the Amish in my area use those BIG "Bullet" shaped horizontal tanks for their air storage for both their shops and houses.

mike4
04-21-2012, 09:02 PM
I'm not sure 6 cfm is large enough to run a die grinder they are air hogs! Typically a 5 hp 2 stage air compressor producing app. 18 cfm will run quite abit using a typical die grinder. Just fyi....

A larger capacity system will be cheaper in the long term as even though you are only wanting to run die grinders now , later you will find that more tools are added and you once adequate compressor cant hack it .
Michael

Robo
04-21-2012, 09:25 PM
Most published air tool usage rates are based on "average cfm" not their "peak" or "real" cfm. I'm telling you from experience if you try to run a die grinder with a 6 cfm air compressor you are going to be disappointed....they use alot of air.

If you are going to invest I would buy a small 2 stage air compressor or a "true" 5 hp commercial unit and be done with it. They can be had fairly cheap if you're patient.

Dr Stan
04-21-2012, 11:08 PM
Quincy is considered by many to be the ultimate in air compressors, but Debilviss, IR, and Speedair also make fine equipment. Two stage is much more efficient than single, but does cost more.

Most of the big box store compressors will give marginal performance. I have a Craftsman 1 1/2 HP portable unit for when I need air outside of the shop, but it really does not perform well. My shop compressor is one I built myself with a Debilviss twin cylinder single stage pump from the Surplus Center and a used 65 gallon tank from an old automotive lift. It does very well unless I'm sandblasting, then I have to wait & let it catch up.

EddyCurr
04-21-2012, 11:28 PM
Regarding grinding. Consider whether an electric die grinder like the Dewalt
DW887 (http://www.dewalt.com/tools/metalworking-grinders-die-grinders-dw887.aspx) or DW888 (http://www.dewalt.com/tools/metalworking-grinders-die-grinders-dw888.aspx) might be substituted for some or all situations where an
air-powered die grinder is used. I have a few brand name die grinders
and several imports fitted with a selection of burrs, drums and wheels.
However, I picked up a DW887 for heavy work.

As noted, heavy die grinding consumes a lot of air. Air is expensive,
electricity less so. Electric d-grinders are bulkier, but if the roughing work
can be managed with one of these, then intermittant detail work with a
air-powered die grinder can be powered by a lower capacity compressor.

An issue with buying more capacity than routinely required is that then
every time air is required, the big motor has to be powered up. A
work-around is to have two smaller compressors. This approach, using
a couple of portables together with an extra receiver/tank served my
hobby needs until recently when I purchased a higher capacity stationary
machine.

.

EddyCurr
04-21-2012, 11:55 PM
Supplemental to the previous post.

I have no personal experience with them, but the Foredom Flex Shaft
grinder (http://www.foredom.net/) has many satisfied users. This might be a suitable
substitute for an air die grinder on fine detailing work.

.

oldtiffie
04-22-2012, 02:37 AM
I need expert advice on Compressors.
I'm in the market for a shop compressor, and don't know which brand to buy.
I need at least 6 CFM's at 90 PSI to run my die grinders.
And I'd like to get a large one with a 60 or 80 gallon tank.
Kobalt (Lowe's) has received bad reviews.
There's also Campbell-Hausfeld, Husky (Home Depot), Craftsman, Dewalt, Horror Freight, etc.
So many brands to choose from.
What do you guys recommend? And how dependable have your compressors been?

What you are after is a compressor that has a good "free air delivery" at the compressor (outlet) as there will be line (pressure and volume) losses until it gets to the tool which requires the 6CFM and 90 psi at the tool while the tool is under load.

Here is my compressoror -

http://i200.photobucket.com/albums/aa294/oldtiffie/Compressor/Compressor_1.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Compressor/Compressor_2.jpg

which is pressurised to 10 Bar (145 psi) and has an air input (suction) of 8.65 CFM but only has a free air delivery (FAD) of 4.15 CFM.

With a big demand such as a 3/8" x 10"/min plasma cutter it is struggling - but gets there as I ease up when I hear the compressor.

With air tools that require 90 psi at the tool I set the regulator to 130psi. Its marvellous how much the relulator (air line) pressure drops when a demand from say an air grinder or an impact wrench is put on it.

My compressor has been 100% reliable and does all that I want of it.

Larger compressors require a lot more power which may mean up-grading a single-phase circuit or installing 3-phase power (the better option if you have it).

If you intend to get an air-blast gun/cabinet, work backwards from the cabinet requirements toward the compressor.

Here is my next compressor.

https://www.machineryhouse.com.au/C506

It is big enough for a small air-blast cabinet and can handle my plasma cutter easily. I am independent of shop power and can work with it any where on the property - outside is easy.

Here is a small sand-blast cabinet - note the air requirements.

https://images.machineryhouse.com.au/S288/0/700

https://www.machineryhouse.com.au/S288

mike4
04-22-2012, 03:01 AM
What you are after is a compressor that has a good "free air delivery" at the compressor (outlet) as there will be line (pressure and volume) losses until it gets to the tool which requires the 6CFM and 90 psi at the tool while the tool is under load.

Here is my compressoror -

http://i200.photobucket.com/albums/aa294/oldtiffie/Compressor/Compressor_1.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Compressor/Compressor_2.jpg

which is pressurised to 10 Bar (145 psi) and has an air input (suction) of 8.65 CFM but only has a free air delivery (FAD) of 4.15 CFM.

With a big demand such as a 3/8" x 10"/min plasma cutter it is struggling - but gets there as I ease up when I hear the compressor.

With air tools that require 90 psi at the tool I set the regulator to 130psi. Its marvellous how much the relulator (air line) pressure drops when a demand from say an air grinder or an impact wrench is put on it.

My compressor has been 100% reliable and does all that I want of it.

Larger compressors require a lot more power which may mean up-grading a single-phase circuit or installing 3-phase power (the better option if you have it).

If you intend to get an air-blast gun/cabinet, work backwards from the cabinet requirements toward the compressor.

Here is my next compressor.

https://www.machineryhouse.com.au/C506

It is big enough for a small air-blast cabinet and can handle my plasma cutter easily. I am independent of shop power and can work with it any where on the property - outside is easy.

Here is a small sand-blast cabinet - note the air requirements.

https://images.machineryhouse.com.au/S288/0/700

https://www.machineryhouse.com.au/S288
Tiffie, looks good but dont leave any unleaded fuel in the carby if you are not going to use it for a while as you will have to replace the seals and clean all the dried crud out before it wiil start .
I have a three cylinder compressor with the same motor and it will handle most of my requirements out of the shop.
Michael

oldtiffie
04-22-2012, 05:14 AM
Thanks Michael.

I am Honda engines greatest fan - bar none.

My first were two relatively small vertical crank-shaft jobs that out-lasted two good mower frames apiece. Those engines as with all my stuff were really well looked after. They lasted about 35 years and they got it hard. All I ever had to do (and I guess it really wasn't needed) were one top overhaul each - no rings needed, the valves just needed a light "lick" and the bores were as clean as .................

We could (did) leave them for 3+ months at a time and they fired up easily - every time.

We retired them about 6 months ago when we bought two new Honda (top to bottom) mowers. I am amazed at how well they go.

Engines fire first or second pull - and with their "easy start" ignition my wife has no trouble at all.

If I buy the new compressor (I think I will - shortly) and if the Honda engine performs half as well as ours did and yours do I will be very happy with it.

I also have a Honda 2KW gen-set that is faultless as well - I carry it around on my ride on mower - so I have power for all my electrical tools anywhere on our 0.4Ha block.

With the new Honda-driven compressor I can do the same with air.

Uncle O
04-22-2012, 07:55 AM
I have a twin-cylinder Speedaire comp. that I have glommed onto a 60/80 (?) gal upright tank. I have had the compressor on various tanks and , using various motors to run it, including the original 30 gal /1 hp set up..
Anyway, I have had it for 10 years, was well used at that time, and it has been very good to me.
Of course you would need something bigger, but I think the brand is reliable.

aboard_epsilon
04-22-2012, 08:16 AM
IVE GOT A 14 CFM 5hp 200 ltr tank COMP ...

the diegrinder starts off initially with 90 psi...after the tank empties after a few mins......its just on the compressor then ..and psi goes down to 60 psi..if running the grinder continuously .

so basically you want the biggest tank you can get ..and if possible over 14 cfm ..

if running intermittently ..then mine does OK .....well 60 psi isnt that bad really, come to think of it .

find another big tank and you could have 90 psi for 20 mins

hope this helps

all the best.markj

John Stevenson
04-22-2012, 08:34 AM
Can you buy Hydrovane compressors over in the US ?

https://encrypted-tbn2.google.com/images?q=tbn:ANd9GcS-jibuCw5oZyBfz-ndgCg0oLAWItM-mkH3Ic2bupkoZk2N2H8u

Not as silent as a screw compressor but you can pick them up quite cheaply.

vpt
04-22-2012, 09:01 AM
Thanks Michael.

I am Honda engines greatest fan - bar none.

My first were two relatively small vertical crank-shaft jobs that out-lasted two good mower frames apiece. Those engines as with all my stuff were really well looked after. They lasted about 35 years and they got it hard. All I ever had to do (and I guess it really wasn't needed) were one top overhaul each - no rings needed, the valves just needed a light "lick" and the bores were as clean as .................

We could (did) leave them for 3+ months at a time and they fired up easily - every time.

We retired them about 6 months ago when we bought two new Honda (top to bottom) mowers. I am amazed at how well they go.

Engines fire first or second pull - and with their "easy start" ignition my wife has no trouble at all.

If I buy the new compressor (I think I will - shortly) and if the Honda engine performs half as well as ours did and yours do I will be very happy with it.

I also have a Honda 2KW gen-set that is faultless as well - I carry it around on my ride on mower - so I have power for all my electrical tools anywhere on our 0.4Ha block.

With the new Honda-driven compressor I can do the same with air.


You should try their vehicles too!

datsun280zxt
04-22-2012, 09:09 AM
I have 2 compressors, the first one a I bought was a "6.5hp" develbiss compressor with a 60gal tank. I've had it for 13years now. Been a great compressor, but would not keep up with sand blasting or my die grinder. It struggled to keep up with any kind of paint gun as well. For a smaller insufficient compressor, the more volume you can get, the better.

A few years ago I bought a "max air" http://www.eaglecompressor.com/air_compressor_model.php?recordID=2833 cylinder compressor, and I've never looked back. That poor other compressor hasn't been fired up more than once since then. Eventually they'll be set up so I can use both in the same air loop and not have to fire up the big one for little operations like bike tires, but most of the time it's fired up, I'm using 60% or more of the air that its putting out. With sandblasting, I can continuously blast and maintain 120psi pressure at the cabinet and the compressor will actually cycle some. Most of the time I'm not blasting at that high of a pressure so it can actually get some rest while blasting. With this newer compressor, I really don't feel like I need extra tanks or anything as I always have the air supply I need. A die grind or 2 would not be a problem. That said, I use a lot of electric die grinders these days. They really are more efficient and seem to work pretty darn good. Keep your hands warm if its cold in the shop too! Air powered ones will freeze you to death!

tmc_31
04-22-2012, 09:30 AM
Another compressor for your consideration is a Rol-Air. Several years ago I bought a "tire buster" from Rol-air. This is a 11 HP (Honda Engine) 2 stage compressor with a 30 gal tank. It delivers 18CFM at 100 PSI. I bought it to run 2- 1/2" impact guns on my job sites. I believe the compressor is built in Italy. Anyway, It has been a very good compressor, not cheap by any means but worth every penny I spent on it. I think these compressors are on par with the Quincy's.

I no longer use it in the field because it is not portable enough and is very top heavy. I am in the process of converting it to electric for use in my shop.

Tim

Seastar
04-22-2012, 10:50 AM
I bought one of these for my shop and it does anything I ask.
Blast cabinet and multiple air power tools.
It is a very well made awsome compressor for a modest price.
http://www.c-aireinc.com/Home/Home.html
Bill

Dr Stan
04-22-2012, 03:31 PM
One possibility is to convert a VW engine to a compressor. I never did so myself, but have read posts from others on different sites who were pleased with the outcome. You may want to look here: http://www.dunnrightinc.com/

I've also seen other examples of V-8's similarly converted including a Ford 5.0 liter V-8. I would suspect a Subaru pancake engine would also be a good candidate for this type of conversion with its balanced design.

gnm109
04-22-2012, 03:56 PM
I have an 80 gallon dual stage compressor with a vertical tank. The compressor block is cast iron and holds one quart of oil.

The motor is made is Canada and is rated at 5hp, 23.0 amps at 1,750 rpm on 240 V. The compressor is rated at 21 SCFM and it will run air tools and my blast cabinet with no problem.

I prefer a vertical compressor due to the smaller footprint. I paid about $1,200 for the compressor about 15 years ago and it's needed nothing except normal maintenance (air cleaner, oil, belt checks, etc.)

The bigger the better in air compressors. It's the star of my tool complement.

http://i144.photobucket.com/albums/r188/gnm109/Machinery/AirCompressorXX-1.jpg

sasquatch
04-22-2012, 06:30 PM
GNM109 You state the motor is made in Canada.

Can you post the name of the motor for us Canucks please?

gnm109
04-22-2012, 07:40 PM
GNM109 You state the motor is made in Canada.

Can you post the name of the motor for us Canucks please?

Sure. I went out to the shop to check the motor plate. It's a Leroy Somer, 23.0 amps, 1740 rpm.

The company where I got the compressor was building them up out of good components. It also has a large magnetic starter built by Telemechanique which, I think was also Canadian at the time (late 90's). They are now owned by Schneider Electric which is either French or French-Canadian. The writing inside of the Starter box is in French and English.

The tank has an ASME certification plate on it. There are two large removable threaded bungs in the side of the tank and I measured the wall of the compressor once after I got it with a micrometer and it was about 1/4" thick.

http://www.leroy-somer.com/catalogue-industry/

http://www.schneider-electric.us/sites/us/en/company/profile/history/telemecanique-transition.page

sasquatch
04-22-2012, 07:58 PM
interesting information , thanks for taking the time to respond to that!

gnm109
04-22-2012, 08:20 PM
interesting information , thanks for taking the time to respond to that!


You are very welcome. :)

browne92
04-23-2012, 12:05 AM
A couple of posters have recommended two stage compressors. I don't. Two stage is for higher pressure (above 125 PSI.) I doubt your die grinders will need that kind of pressure.

Mine is two cylinder, but not two stage. My two cylinder pumps both cylinders into the holding tank for higher volume. Two stage uses one cylinder to compress the air, and a second to compress it again for higher pressure.

I would think you would benefit from higher volume.

Bill

gnm109
04-23-2012, 12:47 AM
A couple of posters have recommended two stage compressors. I don't. Two stage is for higher pressure (above 125 PSI.) I doubt your die grinders will need that kind of pressure.

Mine is two cylinder, but not two stage. My two cylinder pumps both cylinders into the holding tank for higher volume. Two stage uses one cylinder to compress the air, and a second to compress it again for higher pressure.

I would think you would benefit from higher volume.

Bill

My compressor has two gauges: high pressure and low pressure. It is set to shut off at 135 psi and start again at 100. I typically use no more than 90 psi in any application including a die grinder. There would be no necessity to use more than 90 psi in a die grinder regardless of whether the compressor is one stage or two stage.

The principal benefit of the two stage design is that it has substantialyl greater capacity and reserve at the 90 psi setting. This is beneficial for sand blasting, bead blasting and any application that uses large volumes of air where it's important to sustain pressure for longer periods.

If you are not blasting, then probably a single stage one or two cylinder would be fine.

browne92
04-23-2012, 01:25 AM
GNM, you are confusing volume with pressure. I have a two cylinder compressor...rated at 18 CFM. My only reason to purchase it was for sand and bead blasting. Dual stage units are not for providing higher capacities, but higher pressure. While the higher pressure in the tank will give the illusion of providing more volume for a time, a two stage compressor will not refill the tank as quickly.

gnm109
04-23-2012, 10:30 AM
GNM, you are confusing volume with pressure. I have a two cylinder compressor...rated at 18 CFM. My only reason to purchase it was for sand and bead blasting. Dual stage units are not for providing higher capacities, but higher pressure. While the higher pressure in the tank will give the illusion of providing more volume for a time, a two stage compressor will not refill the tank as quickly.

There are nummerous benefits to two stage air ciompressors. .

Advantages of a 2-Stage Pump
A two-stage air compressor is normally used in industrial, commercial and automotive applications where a reliable source is critical. A two-stage air compressor compresses to a higher pressure than single stage air compressor. This allows the air compressor to store more air for future usage. The efficiency in a two-stage air compressor is much higher that in a single stage air compressor. A two-stage air compressor produces more cubic feet of air per horsepower that a single stage air compressor which results in lower operating costs. Also with a two-stage air compressor less heat is generated which reduces the wear and results in a longer life for you air compressor.
http://www.paxontool.com/theadvantagesofa2-stagepump.aspx

Two-Stage vs. Single-Stage
Two-stage air compressors provide a reliable air source in commercial, industrial and automotive applications. Multistage units tend to be more efficient, compressing air to a higher pressure than single-stage compressors. This allows more air to be stored for future use while generating less heat, reducing wear and extending compressor life.
http://www2.northerntool.com/air-compressor-buyers-guide.htm


Benefits
A two-stage air compressor is more energy efficient when compared to other compressors. By using more air power, less heat is generated. The compressor and equipment do not wear easily because heat generation is low. A two-stage air compressor generates more power than traditional electric-power generators, and they are safer than other power generation systems. Industrial jobs get done faster.

http://www.ehow.com/about_5103936_twostage-air-compressor.html


Two Stage Air Compressor Selection for Tampa, Orlando, and Nationwide from Compressed Air SystemsA two stage air compressor can greatly increase the power behind commercial or industrial pneumatic tools. Because this type of heavy-duty compressor operates with two cylinders and two pistons, it’s possible to maintain continued compressor use for long periods of time. The knowledgeable technicians at Compressed Air Systems can help you determine whether a two stage compressor is right for you based on factors like usage frequency, airflow, efficiency, operating costs, and needed pressure. In addition to being able to power air tools for longer periods of time, two stage air compressors are also ideal because they emit less heat than tools that use smaller amounts of air power. This means that your overall energy use is going to be lower, which effectively reduces energy costs.



http://www.compressedairsystems.com/two-stage-air-compressor.html

metalmagpie
04-23-2012, 12:27 PM
I have had lots of compressors. I have some opinions based on experience.

Many cheap compressors are loud and vibrate a lot and get really hot. I can live with vibrating and hot but really loud is a problem for me. AFAIK all small oilless compressors are loud.

Pancake and twin-tank types are intended to run nail guns on a framing crew. They are a very poor choice for general shop work.

If I want to run jackhammers or e.g. sandblast a trailer I rent a big compressor on a trailer. No way I want to buy and install that much capacity in my shop. For me, a true 18 cfm is about right. I can do light sandblasting (e.g. run a 40 lb pressurized sandblaster) adequately enough to not get frustrated, and I can run die grinders. Big air grinders and big air hoists require enormous amounts of CFM - such tools should be left for shipyards or large industrial shops.

Vertical tanks take up less footprint than horizontal. I currently own a Champion 5hp two stage compressor with an 80 gallon vertical tank. I am pleased with it so far. My previous compressor was a Quincy horizontal with 60 gallon tank, also a 5hp 2-stage compressor, with a model 325 pump. A very good quality compressor. Why would I sell it and buy a Champion? Two reasons: the Champion cost less than half what I sold the Quincy for, allowing me budget to build an air piping system; and also the Quincy dated from the 1960s and I simply didn't trust the tank anymore. Which brings me to my final point:

I also have cut open several old air tanks to convert them to meat smokers. Having seen what the inside of a 40 year old air tank looks like, I came to the realization that air tanks, even really good ones, don't last forever, and I sure didn't want one in my shop when it failed. So my last point is an old air pump can be rebuilt, but an old air tank can't. And replacement quality air tanks are really expensive. Especially for 80 gallon vertical ASME-rated tanks.

metalmagpie

MichaelP
04-23-2012, 07:00 PM
There are two most important parameters that you should use to choose your compressor: CFM and duty cycle.

Ideally, your compressor should have 100% duty cycle. I wouldn't buy anything less than that for a shop compressor. You may get by without it if you only use relatively short bursts, with significant idle time in between. A larger tank would be helpful for those compressors too.

As for the CFM, you choose what you need (or may need in the future). Don't skimp on CFH: that's, probably, the most frequent cause of spending money on another compressor. Do yourself a favor and buy as much of it as you can. Tomorrow you may start thinking about sandblasting and will regret spending money on a low CFM compressor.

You absolutely do not need to spend extra money on a 2-stage machine, since you'll hardly ever see any benefits of it. So if you have a choice between extra CFM and the second stage, don't even think twice, get the extra CFM.

The tank volume is less important than those two numbers. It becomes much more important if the duty cycle is less than 100%, especially if the CFM is marginal for your needs.

gnm109
04-23-2012, 07:49 PM
There are two most important parameters that you should use to choose your compressor: CFM and duty cycle.

Ideally, your compressor should have 100% duty cycle. I wouldn't buy anything less than that for a shop compressor. You may get by without it if you only use relatively short bursts, with significant idle time in between. A larger tank would be helpful for those compressors too.

As for the CFM, you choose what you need (or may need in the future). Don't skimp on CFH: that's, probably, the most frequent cause of spending money on another compressor. Do yourself a favor and buy as much of it as you can. Tomorrow you may start thinking about sandblasting and will regret spending money on a low CFM compressor.

You absolutely do not need to spend extra money on a 2-stage machine, since you'll hardly ever see any benefits of it. So if you have a choice between extra CFM and the second stage, don't even think twice, get the extra CFM.

The tank volume is less important than those two numbers. It becomes much more important if the duty cycle is less than 100%, especially if the CFM is marginal for your needs.

I have no idea what the duty cycle is on my compressor but it's more than adequate. It will cycle only occasionally when doing constant bead blasting.

If by 100% duty cycle on a compressor, you mean one where the motor runs constantly, I wouldn't care for one. I want one that only comes on now and then like the one that I have.

The links I posted above state that two stage compressors will have greater reserve and higher pressure. That's what I need so I'm good.

I also think that tank volume is quite important. If I had the room, I'd have a 120 gallon tank. I had an endless succession of smallish single stage compressors before I began searching for the one I have. That was a long time ago and I've never been sorry.

I also think that the compressors with the highest CFM will as a general rule be at least two stage.

MichaelP
04-23-2012, 08:41 PM
If by 100% duty cycle on a compressor, you mean one where the motor runs constantly, I wouldn't care for one. I want one that only comes on now and then like the one that I have.
100% duty cycle is when the compressor is capable of running non-stop if required.

For example, if you run a bead blasting session and CFM of your compressor is even slightly lower than what your blaster consumes,
sooner or later your compressor will need to run non-stop for some time.

Naturally, you don't want your compressor running non-stop every time you do something. That's why you don't buy 10 CFM compressor for 21 CFM blaster or 2 CFM compressors for 4 CFM tools. But, for example, running a 15 CFM compressor with a 18-20 CFM blaster is perfectly fine, as long as your compressor has 100% duty cycle and your tank is not too small. Naturally, you won't be able to blast non-stop for an hour, but you'll be able do complete your job without too much interruptions.

IIRC, compressor duty is rated similar to welding machines: by 10 min increments. For example, a 60% compressor may run only for 6 minutes and then requires 4 minutes rest.

As for the 2-stage ones, they may be beneficial for certain specific high-pressure applications or when used at an industrial level. I'm not aware of any high pressure tool used by HSMers. Keeping 175 psi in your line would require significantly more expensive filters/pressure regulators (and they're more difficult to find used).

I have a 5HP 2-stage 15.6 CFM Quincy in my home shop. The most demanding application is bead blasting (consuming somewhere between 18 and 20 CFM). Occasionally, I use air cooling with my machine tools, and it's also very demanding CFM wise. The compressor is excellent, but I'd trade the second stage for extra CFM any day. I keep 175 psi inside the tank, then, after my DIY cooler, drop it to 100psi with a high pressure filter/regulator, so the line that goes into my shop is at 100 psi. Then, I may either use nothing or plain vanilla regulators and filters throughout the shop. The only benefit of my 2-stage is more air in my 60 Gal tank (that helps too when I blast).

And yes, you're right about 2-stage being a default for many modern compressors of medium and high power. But when there is a choice between higher CFM and ability to have the second stage, choosing higher CFM is a right decision, IMO.

P.S. There is one more benefit of a 100% duty compressor that can be mentioned (although I would prefer never needing it).
If a major leak develops in your air system while you're away (pipe or hose rupture, failed joint, valve problem, etc.), you're not going to lose your compressor or run into a potential fire hazard. It'll just run till you come back.

gnm109
04-23-2012, 09:57 PM
100% duty cycle is when the compressor is capable of running non-stop if required.

For example, if you run a bead blasting session and CFM of your compressor is even slightly lower than what your blaster consumes,
sooner or later your compressor will need to run non-stop for some time.

Naturally, you don't want your compressor running non-stop every time you do something. That's why you don't buy 10 CFM compressor for 21 CFM blaster or 2 CFM compressors for 4 CFM tools. But, for example, running a 15 CFM compressor with a 18-20 CFM blaster is perfectly fine, as long as your compressor has 100% duty cycle and your tank is not too small. Naturally, you won't be able to blast non-stop for an hour, but you'll be able do complete your job without too much interruptions.

IIRC, compressor duty is rated similar to welding machines: by 10 min increments. For example, a 60% compressor may run only for 6 minutes and then requires 4 minutes rest.

As for the 2-stage ones, they may be beneficial for certain specific high-pressure applications or when used at an industrial level. I'm not aware of any high pressure tool used by HSMers. Keeping 175 psi in your line would require significantly more expensive filters/pressure regulators (and they're more difficult to find used).

I have a 5HP 2-stage 15.6 CFM Quincy in my home shop. The most demanding application is bead blasting (consuming somewhere between 18 and 20 CFM). Occasionally, I use air cooling with my machine tools, and it's also very demanding CFM wise. The compressor is excellent, but I'd trade the second stage for extra CFM any day. I keep 175 psi inside the tank, then, after my DIY cooler, drop it to 100psi with a high pressure filter/regulator, so the line that goes into my shop is at 100 psi. Then, I may either use nothing or regular regulators throughout the shop. The only benefit of my 2-stage is more air in my 60 Gal tank (that helps too when I blast).

And yes, you're right about 2-stage being a default for many modern compressors of medium and high power. But when there is a choice between higher CFM and ability to have the second stage, choosing higher CFM is a right decision, IMO.P.S. There is one more benefit of a 100% duty compressor that can be mentioned (although I would prefer never needing it).
If a major leak develops in your air system while you're away (pipe or hose rupture, failed joint, valve problem, etc.), you're not going to lose your compressor or run into a potential fire hazard. It'll just run till you come back.


I remain unconvinced that a single stage compressor would be more beneficial to me than the present two stage that I have.

I'm not aware of any single stage machines that typically give more CFM than two or three stage machines. When I shopped for my machine some 15 or so years ago, I specified a heavy duty unit with 20 or more CFM. All of the ones I saw in that area were two stage. So, I guess I'm not exactly clear on what you are saying
here.

Perhaps we could agree that more CFM is better than less CFM? :D

MichaelP
04-23-2012, 10:29 PM
I'm not aware of any single stage machines that typically give more CFM than two or three stage machines. When I shopped for my machine some 15 or so years ago, I specified a heavy duty unit with 20 or more CFM. All of the ones I saw in that area were two stage. So, I guess I'm not exactly clear on what you are saying
here.

Here is one quick example:

http://www.northerntool.com/shop/tools/product_211720_211720?cm_mmc=Google-pla-_-Air%20Compressors-_-Single%20Stage%20Electric%20Air%20Compressors-_-1592047&ci_sku=1592047&ci_gpa=pla&ci_kw

http://www.northerntool.com/shop/tools/product_200318461_200318461

Single stage 5HP 60 gal 18.1 CFM

vs.

2-stage 5HP 60 gal 14.7 CFM (probably about 15 CFM or so at 90psi)

If I wanted to deal with IR, I'd choose the first compressor. And not because it's much less expensive, but, mostly, because of the higher CFM.

P.S. I cannot recommend "proudly made in India" Ingersoll Rand. :)

gnm109
04-23-2012, 10:47 PM
Motor Fires in Ingersoll Rand Compressors.

http://www.jalopyjournal.com/forum/archive/index.php/t-431341.html

KiddZimaHater
04-23-2012, 11:05 PM
P.S. I cannot recommend "proudly made in India" Ingersoll Rand
YIKES!!
They're really "made in India" ??:eek:
Well, I guess they're off my list.

MichaelP
04-23-2012, 11:15 PM
They're really "made in India" ??:eek:

AFAIR, some of their models are. You may want to recheck this info.

gnm109
04-23-2012, 11:40 PM
YIKES!!
They're really "made in India" ??:eek:
Well, I guess they're off my list.

Yes, Memsahib, that is true.

EddyCurr
04-24-2012, 12:11 PM
If 100% duty cycle is desired/required, my vote is that a screw compressor
should be purchased instead of looking at a reciprocal. One approach to
sizing a reciprocal is discussed on pg 9 here (http://www.centrair.ca/brochures/Infobook.pdf). There will be variations on this
method but none of them will involve choosing a unit only capable of 100%
or less of continuous demand.


Vertical tanks take up less footprint than horizontal.As a counterpoint, a horizontal tank can be placed under a bench or within
a shelving/cupboard unit where, with adequate provisions for ventiation and
maintenance, it can be enclosed for quieter operation. Also, horizontals are
easier to transport safely when the occasion arises, due to their much lower
center of gravity and broader footprint.

An enclosed bench, mounted on casters with a work surface height of 51"
& w/ under-tabletop storage on one side is the future home for this 80 gal
unit (49"H x 63"L x 22"W). Rated for 19CFM @ 175psi (two-stage.) Pressure
lubricated. 5 HP motor at 1725 RPM. Operates at 78dBA unenclosed (you
can converse easily standing beside it.) Optional automatic drain.

http://www.slalom4me.com/imaged_a01/jpg/Other/Shop/Air/2012.04.24_Devair_01.jpeg


If I want to run jackhammers or e.g. sandblast a trailer I rent
a big compressor on a trailer.Full agreement.


Having seen what the inside of a 40 year old air tank looks like, ...Here, Princess Auto sells 60G & 80G tanks finished in primer that are
certified, though I do not know whether to ASME. I would consider the
re-tanking route if I found a complete large capacity old unit in good
condition. I dismissed doing this for a less robust compressor because the
price difference against a new unit was too small, especially when visual
appearance and future resale was considered.

.

radkins
04-24-2012, 12:52 PM
The Ingersoll compressors are NOTORIOUS for burning out motors! There was a thread on an automotive forum that had FIVE members with the same problem at the same time! :eek: Also the 5 HP single stage that is rated at 18+ CFM@90 PSI is just flat out exaggerated and I seriously doubt a 5 HP single stage could produce that much air, some sellers have started rating the same compressor at a more realistic 15+ CFM. Also don't place too much confidence in a larger tank increasing a compressor's performance, it won't and this is probably the most common misunderstanding about compressor capabilities. It does not matter how big the tank is (within reason) because after the first start-up cycle any gains from the extra tank capacity is going to be lost to the proportionally longer recharge time so it is a wash, increased performance is not the purpose of the larger tank. The tank is sized to balance the run and idle/cooling cycles and over a given work period the run vs recharge time will remain exactly the same regardless of tank size, fewer but longer run/charge cycles vs shorter more frequent cycles.

Dr Stan
04-24-2012, 02:25 PM
Here, Princess Auto sells 60G & 80G tanks finished in primer that are certified, though I do not know whether to ASME.

I cannot recall the name, but the mechanical standards certification agency in Canada has just as stringent and sometimes more stringent requirements than the ASME.

EddyCurr
04-24-2012, 02:40 PM
I cannot recall the name, but the mechanical standards certification
agency in Canada ...Perhaps tanks come under the auspices of CSA (Canadian Standards
Association) here. I do not know.

No details on the website. They would respond to a question if asked.

60 Gal Tank (http://www.princessauto.com/pal/product/8068876/Vertical/60-Gallon-Air-Compressor-Tank)

80 Gal Tank (http://www.princessauto.com/pal/product/8377624/Electric/80-GALLON-AIR-TANK)

.

Dr Stan
04-24-2012, 03:08 PM
Perhaps tanks come under the auspices of CSA (Canadian Standards Association) here.


That's it. Thanks, had to be something simple as its Canadian, not US. :rolleyes:

KiddZimaHater
04-24-2012, 09:41 PM
Well, I confirmed the "Ingersoll Rand - Made in India" theory.
I went to my local LOWE'S and looked at the big 80 Gallon, 5 HP compressor.
Compressor had a placard on it, "MADE IN INDIA".
Then I checked out the motor. It was some unfamiliar brand name, with a "Made in Mexico" decal on the side of it.
I think I'll pass.:(

gnm109
04-24-2012, 10:39 PM
Well, I confirmed the "Ingersoll Rand - Made in India" theory.
I went to my local LOWE'S and looked at the big 80 Gallon, 5 HP compressor.
Compressor had a placard on it, "MADE IN INDIA".
Then I checked out the motor. It was some unfamiliar brand name, with a "Made in Mexico" decal on the side of it.
I think I'll pass.:(


One thing I've noticed in the Ingersoll Rand advertisements shown above in links as well as others that I've seen is that they don't mention the rpm of the motor. I've had a number of smaller single stage compressors that used 3,450 rpm motors. They really have to work to get up to pressure so that they can shut off. I think that may have something to do with the high number of casualties in their motors.

In like manner, my first rotary phase converter was a Phoenix Brand that I bought on eBay. It worked OK, except it seemed to be somewhat underpowered considering that it was rated at 5 hp. It was fitted with a Chinese 3,450 rpm motor. The problem with it was that you couldn't hear yourself think when it was running. It had a high-pitched sound that was terribly annoying.

I sold it cheap with full dlsclosure and built one with a true 5 ph 3 ph motor that runs at 1,750 rpm. The difference is like night and day. I can still hear it but it's got a pleasant hum that is not a problem at all.

So, any compressor that I would buy would be one with a 1,750 rpm motor, regardless of whether it was single or twin phase.

lakeside53
04-24-2012, 11:45 PM
I can't hear my 3600 rpm motor when the 2 stage Quincy pump it's driving is running;)

Whether it uses a 2 pole or 4 pole motor is just a pulley size. Quincy thought the 3600 was a better choice, for whatever reason.

amatts
04-27-2012, 03:27 PM
YIKES!!
They're really "made in India" ??:eek:
Well, I guess they're off my list.
Well,they been global for 100yrs+...but,when the corporate HQ banged off to the Bahamas in the early 90's,I sold ALL my IR stock..worked for a sub of thiers for 11yrs.I would still buy a T30..best ever made (A US one,though)