It seems a little personal, but I'm shopping for air compressors and was wondering how big is big enough? I was looking at a 40 gallon one...what do you think? Is it all about psi? I'd like one big enough to use for a while before it clunks on and refills, thus saving what little is left of my hearing.
inquiringgal
*ahem* how big is your compressor?
Moderators: Brad Walker, Tony Smith
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Tony Smith
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I have a 7 hp/60 gallon compressor, but the other night I really wish I had a 15 hp/120 gallon compressor... it was running about 75% of the time for more than a half hour... it seems like there's never enough money, air, or power!
Tony
Tony
The tightrope between being strange and being creative is too narrow to walk without occasionally landing on both sides..." Scott Berkun
Funny you should ask about air compressors. I just bought this one http://www.porter-cable.com/index.asp?e=547&p=4699 and the first time I used it it blew the breakers in my garage. Had to have a new electrical panel put in this weekend to accommodate it. And surprisingly, it's much quieter than my old tiny one.
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jim simmons
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Re: *ahem* how big is your compressor?
I would think that you would want one that delivers the most cfm at at least 90 psi.Cheryl wrote:It seems a little personal, but I'm shopping for air compressors and was wondering how big is big enough? I was looking at a 40 gallon one...what do you think? Is it all about psi? I'd like one big enough to use for a while before it clunks on and refills, thus saving what little is left of my hearing.
inquiringgal
That said, The oilless compressors are a LOT more noisy than the oil lubed ones.
I don't know anything about possible oil contamination though.
Jim
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Steve Immerman
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Cheryl,
I went through a similar line of questioning last winter. I wanted one that wasn't too large, since I had to navigate it down to the basement. I ended up with this one:
Campbell Hausfeld VT6271, VT6271 6 HP, 26 Gallon, Twin
Cylinder, Oil Lubricated, Single Stage Portable Air Compressor $449.00.
http://www.buykimco.com/vt6271.html
I've been very happy with it. Not too large,not too noisy, has wheels, 10.3 CFM at 90 psi, and a really nice blue color.
When I'm doing light blasting, it seems that it is on about 15% of the time.
Steve
I went through a similar line of questioning last winter. I wanted one that wasn't too large, since I had to navigate it down to the basement. I ended up with this one:
Campbell Hausfeld VT6271, VT6271 6 HP, 26 Gallon, Twin
Cylinder, Oil Lubricated, Single Stage Portable Air Compressor $449.00.
http://www.buykimco.com/vt6271.html
I've been very happy with it. Not too large,not too noisy, has wheels, 10.3 CFM at 90 psi, and a really nice blue color.
When I'm doing light blasting, it seems that it is on about 15% of the time.
Steve
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Mark Selleck
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compressor size
Cheryl, you need to figure out how much air you need: what pressure you want to blast at (are you frosting, carving, removing irid coatings, etc.), what size nozzle you are going to use(how big are the areas you plan to be blasting), and what type of sandblast system you plan to purchase: suction or pressurized being the most common. I have four 5HP compressors hooked up in-line, each with an 80 gal. tank, and I use every bit of air they supply, running continuously for up to 6 hours at a time. But I'm doing a lot of large (up to 8'x12') pieces, and a lot of deep carving. For most sandblasting purposes, the size of the tank is almost irrelevent, unless you're only doing relatively small pieces, or are blasting small areas. Depending on the size of the nozzle and pressure, most sandblasting will drain the air in a storage tank in a matter of a couple of minutes. Your compressor should supply at least as much air as you need for continuous operation without expecting "help" from the storage tank. Again, unless you are working light. If you'd like to post more info as to what you're interested in doing, or contact me directly, I'd be happy to try to help with your decision.
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Tony Smith
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There is an article on Sandcarver.org that discusses compressor selection for sandblasting and compares the compressor requirements for pressure pot vs siphon blaster vs nozzle size etc.... http://www.sandcarver.org/air_compressor_selection.htm
Mark is correct that you need to decide what you want to do with it. If it is strictly for utility blasting on small pieces (plate size and smaller): iow etching the surface of glass, etching off kilnwash and etching through dichroic coating or iridizing, then you can get away with a much smaller compressor than you would need for stage carving, deep etching or sculpture.
The compressor that Steve has is perfect for his application: portable, small and relatively quiet with <50% duty cycle when used with his equipment for his process.
I have a good friend who has been using a Sears compressor similar to the Porter-Cable shown above for his studio since I've known him. He teaches basic sandblasting and stage carving and does some contract sandblasting, and it has never overheated or failed to provide enough air for his application.
So a few points to make are:
Pressure pots require less pressure and less volume than siphon blasters. I typically use my pressure pot at 20 psi with a 7/64"Ø nozzle so I use 50 psi air from the compressor. If I'm doing a batch of dichroic pins, I can typically run my entire batch on whatever air is left in the compressor tank from the last time I ran it.
Siphon blasters use the higher pressure and greater volume of air to create the suction needed to draw the abrasive up into the gun. Siphon Blasters typically run at 80 to 90 psi.
Large compressors (60 gallon and larger) typically require 30 Amp, 220VAC electrical service (or more) and need to be installed by a qualified electrician.
The size of the tank provides you with a reserve air supply. It provides a buffer when the air demand increases and allows the compressor to shut off periodically and cool down while still providing air. In Marks's case, where his air demand is high and constant, he has several compressors running continuously to keep the tank pressurized. This is a common setup in industrial compressors. Industrial compressors are rated for contiuous operation, 24/7. Consumer compressors are not rated for continuous service (100% duty cycle) instead, they are supposed to be run no more than 50% of the time. For Steve's compressor, running 15% of the time will ensure that his compressor lasts a long time. Having excess capacity is a key to longevity with compressors.
Nozzle size directly affects air consumption (inverse square relationship). So if you are doing small work, and can use a small diameter nozzle with a pressure pot, your air volume requirement will go way down.
Motor speed, lubrication type and number of cylinders all contribute to the noise level. High speed, single cylinder, permanently lubricated (non-oil) compressors are very noisy and are the most common compressors for consumers... although this trend seems to be changing. I am seeing many more belt-drive, twin cylinder, oil-lubricated compressors on the market which are much quieter than the screamer that I currently have.
Finally, there are only 3 or 4 manufacturers of consumer-grade compressors in the US. So whether it has a Sears, Campbell-Hausfield, Ace Hardware, Porter-Cable or Home Depot label on it, there's a very good chance that they are made by either DeVilbiss, Campbell Hausfeld or Ingersol Rand. On the other hand, there are almost 500 industrial compressor manufacturers listed in the Thomas Register.
Bottom line: if you are doing what most of us are doing, and that's utility sandblasting, etching and occasional carving on plate-size pieces or smaller, you can get away with a moderate size compressor like Steve has... although there is some value to the old adage that you should buy as much air compressor as you can afford since you never know when you'll be bit by the bug and want to do more, bigger, faster, deeper...
Tony
Mark is correct that you need to decide what you want to do with it. If it is strictly for utility blasting on small pieces (plate size and smaller): iow etching the surface of glass, etching off kilnwash and etching through dichroic coating or iridizing, then you can get away with a much smaller compressor than you would need for stage carving, deep etching or sculpture.
The compressor that Steve has is perfect for his application: portable, small and relatively quiet with <50% duty cycle when used with his equipment for his process.
I have a good friend who has been using a Sears compressor similar to the Porter-Cable shown above for his studio since I've known him. He teaches basic sandblasting and stage carving and does some contract sandblasting, and it has never overheated or failed to provide enough air for his application.
So a few points to make are:
Pressure pots require less pressure and less volume than siphon blasters. I typically use my pressure pot at 20 psi with a 7/64"Ø nozzle so I use 50 psi air from the compressor. If I'm doing a batch of dichroic pins, I can typically run my entire batch on whatever air is left in the compressor tank from the last time I ran it.
Siphon blasters use the higher pressure and greater volume of air to create the suction needed to draw the abrasive up into the gun. Siphon Blasters typically run at 80 to 90 psi.
Large compressors (60 gallon and larger) typically require 30 Amp, 220VAC electrical service (or more) and need to be installed by a qualified electrician.
The size of the tank provides you with a reserve air supply. It provides a buffer when the air demand increases and allows the compressor to shut off periodically and cool down while still providing air. In Marks's case, where his air demand is high and constant, he has several compressors running continuously to keep the tank pressurized. This is a common setup in industrial compressors. Industrial compressors are rated for contiuous operation, 24/7. Consumer compressors are not rated for continuous service (100% duty cycle) instead, they are supposed to be run no more than 50% of the time. For Steve's compressor, running 15% of the time will ensure that his compressor lasts a long time. Having excess capacity is a key to longevity with compressors.
Nozzle size directly affects air consumption (inverse square relationship). So if you are doing small work, and can use a small diameter nozzle with a pressure pot, your air volume requirement will go way down.
Motor speed, lubrication type and number of cylinders all contribute to the noise level. High speed, single cylinder, permanently lubricated (non-oil) compressors are very noisy and are the most common compressors for consumers... although this trend seems to be changing. I am seeing many more belt-drive, twin cylinder, oil-lubricated compressors on the market which are much quieter than the screamer that I currently have.
Finally, there are only 3 or 4 manufacturers of consumer-grade compressors in the US. So whether it has a Sears, Campbell-Hausfield, Ace Hardware, Porter-Cable or Home Depot label on it, there's a very good chance that they are made by either DeVilbiss, Campbell Hausfeld or Ingersol Rand. On the other hand, there are almost 500 industrial compressor manufacturers listed in the Thomas Register.
Bottom line: if you are doing what most of us are doing, and that's utility sandblasting, etching and occasional carving on plate-size pieces or smaller, you can get away with a moderate size compressor like Steve has... although there is some value to the old adage that you should buy as much air compressor as you can afford since you never know when you'll be bit by the bug and want to do more, bigger, faster, deeper...
Tony
The tightrope between being strange and being creative is too narrow to walk without occasionally landing on both sides..." Scott Berkun
After quizzing others from the board I ordered a compressor which matched the criteria for my studio as I imagined it in 5 years ie- rating of air tools and sandblasting/carving. I got a 3 phase 415V - 50cfm compressor. At first I was embarrassed by the shear size of it because I work from home and it looked way too serious. Now I wouldn't have it any other way after already getting stuck into all of its intended uses and not causing any stir in the village. Haydo
Life is like a raft, so be like a rat!...Challenging being a captain type rat though, going down with each ship and all!!
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Mark Selleck
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compressor size
Tony's detailed comments pretty much covered it all. One more thing, relating to longevity and noise: you should check into "industrial" compressor sources if you are in this for the long haul. Cost will probably be a little higher, but you will have more choices. Compressors commonly available from industrial manufacturers are more likely designed with longevity in mind, which often translates to cast-iron compressor heads instead of aluminum, and lower revolutions/minute, which translates to less noise. I am in the process of replacing three of my compressor heads. They all have aluminum heads, and have given me good service for almost 15 years. They are loud. LOUD. My fourth compressor is a cast-iron unit, and runs at half the revs of the others, producing the same amount of air. It is comfortable standing two feet away from it, and 25 feet away it is barely noticable when it is running. My neighbors are going to think I've stopped working when the new heads are all set up. The closest home is 500' away, but I know they are aware every time the compressor bank comes on.
Another consideration is whether a single-stage compressor will suffice, or whether you need a two-stage. If you are using tools that mainly need volume of air (sandblasting, most air tools) rather than high pressure, then a single-stage compressor will be fine, and they are less expensive. If you have plans for the future that will require a lot of high-pressure air, then a two-stage compressor would be desireable.
The bottom line is: First figure out what you want to do with your system, considering immediate needs and how those needs might change in the near future. Then set about getting the compressor that will fill those needs.
Another consideration is whether a single-stage compressor will suffice, or whether you need a two-stage. If you are using tools that mainly need volume of air (sandblasting, most air tools) rather than high pressure, then a single-stage compressor will be fine, and they are less expensive. If you have plans for the future that will require a lot of high-pressure air, then a two-stage compressor would be desireable.
The bottom line is: First figure out what you want to do with your system, considering immediate needs and how those needs might change in the near future. Then set about getting the compressor that will fill those needs.
5 hp, 200#?
There's an auction tomorrow am that includes a 5 HP, 200 pound compressor. No other specs available (and I don't know whether it comes in blue, although that is one of my favorite colors). Should I go for it? If so, how much should I pay?
I just blast off irrid, kilnwash, and micas for photoresist, but I could see myself someday wanting to create holes.
I just blast off irrid, kilnwash, and micas for photoresist, but I could see myself someday wanting to create holes.
Re: 5 hp, 200#?
they don't rate them by weight, but by lbs per square inch (psi). sure it's not 200 psi? if so, it's going to be way heavy, since it's got to be pretty beefy since a standard one is 125-135 psi, and you need lots more metal to hold back that pressure.Cheryl wrote:There's an auction tomorrow am that includes a 5 HP, 200 pound compressor. No other specs available (and I don't know whether it comes in blue, although that is one of my favorite colors). Should I go for it? If so, how much should I pay?
I just blast off irrid, kilnwash, and micas for photoresist, but I could see myself someday wanting to create holes.
remember, basically, a compressor tank is a bomb.
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Tony Smith
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without knowing more about the compressor (whether it runs, if it has ever been drained, if it requires 440VAC) I would be hesitant to buy it without a lot more information... it might be totally unusable to you.
Tony
Tony
The tightrope between being strange and being creative is too narrow to walk without occasionally landing on both sides..." Scott Berkun
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Joseph Tracy
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Cheryl
If you have a cabinet and good quality gun, see what the manufacturer of the gun reccomends for an air compressor. CFM (Cubic Feet of air per Minute) is the most critical factor. You need less CFM if you have a pressure blaster. There are small units that will do an excellent job but cheap generally means low perfomance and headaches. Get a good moisture filter too. Moisture quickly clogs sandblasters.
Hope something in here along with the other excellent feedback helps.
If you have a cabinet and good quality gun, see what the manufacturer of the gun reccomends for an air compressor. CFM (Cubic Feet of air per Minute) is the most critical factor. You need less CFM if you have a pressure blaster. There are small units that will do an excellent job but cheap generally means low perfomance and headaches. Get a good moisture filter too. Moisture quickly clogs sandblasters.
Hope something in here along with the other excellent feedback helps.
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Lynne Chappell
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Perhaps the 200 lb relates to a pressure pot that comes with the compressor. I would think that any 5 HP compressor would suffice for small work. But I wouldn't pay too much as you don't know what shape it's in. A new industrial grade 5 HP compressor would sell here in Canada for maybe $1500-2000 (Cdn - that's about 2 cents US - well actually 1000-1400). A new consumer 5 HP compressor (and there really is a difference) maybe $500-800 (Cdn). The pressure pot, etc. is not included.
I started with a 2HP portable 220V compressor from Sears, which is probably all I would ever need for my fusing needs. Then moved up to a good 5HP compressor delivering 17 CFM. This was enough to sandblast (and carve) fairly large pieces of glass but it did turn on too often (and was loud). With the next upgrade, I decided to skip the 10HP phase, and go straight to 15HP delivering 43 CFM. We carve and sandblast large (well I can't get anything larger than 10 feet long in the room) windows as well as run an air hood (requiring 12 CFM all by itself). It hardly ever turns on, but we put it in a soundproof room before we discovered this. If you're standing right next to it when it comes on, you jump 5 feet in the air.
As you can see, compressors are sort of like kilns, (and boats). Next year you always want a bigger one.
Lynne
I started with a 2HP portable 220V compressor from Sears, which is probably all I would ever need for my fusing needs. Then moved up to a good 5HP compressor delivering 17 CFM. This was enough to sandblast (and carve) fairly large pieces of glass but it did turn on too often (and was loud). With the next upgrade, I decided to skip the 10HP phase, and go straight to 15HP delivering 43 CFM. We carve and sandblast large (well I can't get anything larger than 10 feet long in the room) windows as well as run an air hood (requiring 12 CFM all by itself). It hardly ever turns on, but we put it in a soundproof room before we discovered this. If you're standing right next to it when it comes on, you jump 5 feet in the air.
As you can see, compressors are sort of like kilns, (and boats). Next year you always want a bigger one.
Lynne