30 gallon Gas compressor

[alex123]

Hello All,

I need a gas compressor and 90% of the work I do will be automotive repair related. I know IR, DeWalt, Quincy, and some other brands offer some great compressors starting at around $2100, but I'm wondering if I can get away with getting the Harbor Freight Central Pneumatic one? The price is significantly less at $1349. The tools I MUST be able to run are the following: Air hammer, air impact wrench (3/4"), die grinder, cut off tool, air saw/ speed saw, grease gun, and some light spray paint. The central pneumatic is rated at 18cfm @ 90psi, but I honestly don't trust HF specs on anything. Will this compressor suffice, or do I need to upgrade to something with a higher CFM rating? (btw, upgrading to a 220V is not an option)

Thanks

 

[LeeG]

My guess is that for a single user, that compressor will suffice for anything except probably media blasting, even if the specs are off by 30%. Extended die grinder use may also be an issue. Getting service on it may be an issue in the long term.

A significantly better overall unit would be something like this Rolair Truck Mount. It at least will have maintenance parts available, but it is about $1000 more.

I have the electric version of the above Rolair, and it produces air faster than my my blowgun can use it.

 

[alex123]

My guess is that for a single user, that compressor will suffice for anything except probably media blasting, even if the specs are off by 30%. Extended die grinder use may also be an issue. Getting service on it may be an issue in the long term.

A significantly better overall unit would be something like this Rolair Truck Mount. It at least will have maintenance parts available, but it is about $1000 more.

I have the electric version of the above Rolair, and it produces air faster than my my blowgun can use it.

@LeeG Thank you for your response. Without a doubt, the unit you've posted is better. However, as you mentioned, it's almost $1000 more. That's almost double the price of the CP. You mentioned extended die grinder use being an issue with the CP. Two questions relating to this: (1) What kind of run time should I expect for the die grinder on the CP (on avg.). and (2) Will adding a separate tank for added capacity be an option with the CP?

Thanks

 

[TonyJ]

It’s not the tank size that will concern you as much because gas compressors work differently than electric. Electric compressors start and stop via a pressure switch. Gas compressors don’t shut off when the pressure is up. They unload the unused air but the motor and pump keep a turning and adds air when the pressure drops to it’s needed point. In the gas world it’s all about the pump cfm and how much your tool is using and the pump keeps up with the tool. Electric world you want more storage ( tank size ) so that the pump and motor doesn’t have to cycle as much. Even then the pump has to put out greater cfm than what your using or it will still run all the time. And in saying all of this is why when your looking at gas compressors vs electric ones you will notice that gas compressor have almost always 30gal tanks and higher cfm ratings than a electric compressor when the same pump is used on both.


Tony

 

[alex123]

@TonyJ - Thank you for the helpful information. Given what you've mentioned, will the 18cfm @90 psi rating provided by Harbor Freight's Central Pneumatic suffice for my needs? The tools I MUST be able to run are the following: Air hammer, air impact wrench (3/4"), die grinder, cut off tool, air saw/ speed saw, grease gun, and some light spray paint. Thanks again!

 

[redmondjp]

@TonyJ - Thank you for the helpful information. Given what you've mentioned, will the 18cfm @90 psi rating provided by Harbor Freight's Central Pneumatic suffice for my needs? The tools I MUST be able to run are the following: Air hammer, air impact wrench (3/4"), die grinder, cut off tool, air saw/ speed saw, grease gun, and some light spray paint. Thanks again!

The high-flow, continuous-use tools like die grinder and cutoff tool consume a remarkable amount of air, but 18cfm should be enough to run any one of those tools. Better-quality air tools will have more efficient (less leaky) motors that use less cfm.

For your 3/4" air impact, the biggest factor in determining how well it works is to have a high-flow air path all the way from the tank directly to your tool. There are hundreds of threads on this site discussing high-flow air couplers and the like. Hint: use a site-specific google search to find them - in google, type "site:garagejournal.com" followed by a space and whatever search term you want to look for. That will only search this site.

Ideally, you're going to want a direct tank connection that does NOT go through a regulator or a lot of tiny fittings (best case - 3/8" or 1/2" hose barb on tank, directly to hose barb on gun). The less fittings in the path, the better. You may want to have one dedicated hose connected to the compressor tank just for the 3/4" gun. And the higher the pressure, the more ugga duggas you are going to get out of the gun. Yes, they all say max 90psi or whatever, but anybody who works in a shop with 150psi air (or 130, etc.) will tell you that it does make a difference in torque when you are running a higher pressure.

 

[alex123]

The high-flow, continuous-use tools like die grinder and cutoff tool consume a remarkable amount of air, but 18cfm should be enough to run any one of those tools. Better-quality air tools will have more efficient (less leaky) motors that use less cfm.

For your 3/4" air impact, the biggest factor in determining how well it works is to have a high-flow air path all the way from the tank directly to your tool. There are hundreds of threads on this site discussing high-flow air couplers and the like. Hint: use a site-specific google search to find them - in google, type "site:garagejournal.com" followed by a space and whatever search term you want to look for. That will only search this site.

Ideally, you're going to want a direct tank connection that does NOT go through a regulator or a lot of tiny fittings (best case - 3/8" or 1/2" hose barb on tank, directly to hose barb on gun). The less fittings in the path, the better. You may want to have one dedicated hose connected to the compressor tank just for the 3/4" gun. And the higher the pressure, the more ugga duggas you are going to get out of the gun. Yes, they all say max 90psi or whatever, but anybody who works in a shop with 150psi air (or 130, etc.) will tell you that it does make a difference in torque when you are running a higher pressure.

@redmondjp - Thank you so much for that Google trick!! (I honestly didn't know you could do site specific searches like that). You read my mind on the fittings and couplers, as I was about to go research that next. A couple of quick questions on the points you mentioned above:
(1) You mentioned reducing where possible. Would a air line filter adversely affect performance if added?
(2) You mentioned having a dedicated hose for the 3/4" gun - What size hose do you recommend, and more importantly, can this same size hose be used for my other tools that aren't air hogs? (In other words, use the 3/4" gun hose for all tools.
(3) You mentioned higher psi making a difference in torque. With the central pneumatic tank (180 psi), I should be able to run my tools at a higher psi with no problems right?

Thank you again!

 

[LeeG]

Alex,
It really all depends upon the actual performance of the unit. My compressor's actual stats are a bit better than the listed stats for the CP unit, and I literally cannot run out of air with it using a 3/8" hose. If I open up a blow gun on the end of a 50' 3/8" hose, my compressor will only run about 1/2 the time.

If the actual stats are as good as what is listed, you should be good to go. If they are worse, then it really depends on what they actually are. An extra storage tank will only help for burst activity.

 

[alex123]

Alex,
It really all depends upon the actual performance of the unit. My compressor's actual stats are a bit better than the listed stats for the CP unit, and I literally cannot run out of air with it using a 3/8" hose. If I open up a blow gun on the end of a 50' 3/8" hose, my compressor will only run about 1/2 the time.

If the actual stats are as good as what is listed, you should be good to go. If they are worse, then it really depends on what they actually are. An extra storage tank will only help for burst activity.

@LeeG - Many thanks for your input. I'm not sure how I would be able to find out if the numbers are better/worse than what's published. Any way of finding out, other than having to bring the unit home?
Which compressor are you using if you don't mind me asking?

 

[LeeG]

Mine is an older model, but basically the same as the 30 gallon one here.

https://www.rolair.com/products/air-compressors/electric-stationary/3-hp-two-stage#models

I put a 100psi regulator on at my hose reel as most of the tools I use only want 90psi or so.

I've been very happy with it. I was able to get it used for $300, so quite a steal.

 

[redmondjp]

@redmondjp - Thank you so much for that Google trick!! (I honestly didn't know you could do site specific searches like that). You read my mind on the fittings and couplers, as I was about to go research that next. A couple of quick questions on the points you mentioned above:
(1) You mentioned reducing where possible. Would a air line filter adversely affect performance if added?
(2) You mentioned having a dedicated hose for the 3/4" gun - What size hose do you recommend, and more importantly, can this same size hose be used for my other tools that aren't air hogs? (In other words, use the 3/4" gun hose for all tools.
(3) You mentioned higher psi making a difference in torque. With the central pneumatic tank (180 psi), I should be able to run my tools at a higher psi with no problems right?

Thank you again!

I've never owned a 3/4" gun so I'll let others who have direct experience input what has worked for them. You get the point I made - for most air tools, the restrictions don't matter nearly as much. For that size compressor with a small tank and a 3/4" gun, it may well matter. There is no harm in experimenting with your own setup to see what helps and what doesn't. You could plumb right off the tank and then have one high-flow disconnect at the tool, so you could then run anything off of that hose.

I wouldn't run an air filter - that will really restrict your flow - unless you need it for painting - I typically use the plastic disposable ones at the gun.

If you have a single-stage compressor, I would run unregulated to the tools. If you have a two-stage, the shops I have worked in ran 130-150psi range and still ran direct to air tools w/o regulation. I don't know that I would put 175psi to any of my air tools, personally. That's just me.

 

[alex123]

I've never owned a 3/4" gun so I'll let others who have direct experience input what has worked for them. You get the point I made - for most air tools, the restrictions don't matter nearly as much. For that size compressor with a small tank and a 3/4" gun, it may well matter. There is no harm in experimenting with your own setup to see what helps and what doesn't. You could plumb right off the tank and then have one high-flow disconnect at the tool, so you could then run anything off of that hose.

I wouldn't run an air filter - that will really restrict your flow - unless you need it for painting - I typically use the plastic disposable ones at the gun.

If you have a single-stage compressor, I would run unregulated to the tools. If you have a two-stage, the shops I have worked in ran 130-150psi range and still ran direct to air tools w/o regulation. I don't know that I would put 175psi to any of my air tools, personally. That's just me.

I just double checked and my impact wrench is actually 1/2", and not 3/4". The Central Pneumatic should suffice right?

 

[alex123]

I've never owned a 3/4" gun so I'll let others who have direct experience input what has worked for them. You get the point I made - for most air tools, the restrictions don't matter nearly as much. For that size compressor with a small tank and a 3/4" gun, it may well matter. There is no harm in experimenting with your own setup to see what helps and what doesn't. You could plumb right off the tank and then have one high-flow disconnect at the tool, so you could then run anything off of that hose.

I wouldn't run an air filter - that will really restrict your flow - unless you need it for painting - I typically use the plastic disposable ones at the gun.

If you have a single-stage compressor, I would run unregulated to the tools. If you have a two-stage, the shops I have worked in ran 130-150psi range and still ran direct to air tools w/o regulation. I don't know that I would put 175psi to any of my air tools, personally. That's just me.

Okay, this is probably gonna sound really silly but I just had an idea and wanted to run it by you. What if I bought two of these 30 gallon compressors and plugged one in the 110v wall outlet, and powered the other one off a generator? My main issue is that I do not have access to a 220V outlet, and can not get one installed. I move often, and so wiring rental units to 220v every time I move is definitely not an option. Would this be a better alternative to gas powered air compressors?

 

[TonyJ]

Okay, this is probably gonna sound really silly but I just had an idea and wanted to run it by you. What if I bought two of these 30 gallon compressors and plugged one in the 110v wall outlet, and powered the other one off a generator? My main issue is that I do not have access to a 220V outlet, and can not get one installed. I move often, and so wiring rental units to 220v every time I move is definitely not an option. Would this be a better alternative to gas powered air compressors?

How about this silly question lol. Do you have an electric dryer or an electric stove or even an electric furnace? If so then all of those usually has a 30amp breaker or higher. If so a simple tap can be made and used as long as your not using both at the same time then you can step up to a 220v model and end all of your worries


Tony

 

[alex123]

How about this silly question lol. Do you have an electric dryer or an electric stove or even an electric furnace? If so then all of those usually has a 30amp breaker or higher. If so a simple tap can be made and used as long as your not using both at the same time then you can step up to a 220v model and end all of your worries


Tony

A 220v setup would definitely take care of my issues. I do have an electric dryer and stove.... but won't that require the use of an extension cable, which in turn draws way too many amps (ie: blow the fuse in the fuse box).

Edit: While researching, I came across some 10 gallon gas compressors as well. The cfm is only rated at 12.5cfm at 90psi though. However, another option that came to mind was buying the 10 gallon gas compressor and buying an empty 30 gallon tank. This would give me 10 extra gallons versus buying just a 30 gallon truck mount unit, and it would be significantly cheaper. Not sure if this is reasonable or if that cfm would suffice for my automotive tools?

 

[TonyJ]

A 220v setup would definitely take care of my issues. I do have an electric dryer and stove.... but won't that require the use of an extension cable, which in turn draws way too many amps (ie: blow the fuse in the fuse box).

Edit: While researching, I came across some 10 gallon gas compressors as well. The cfm is only rated at 12.5cfm at 90psi though. However, another option that came to mind was buying the 10 gallon gas compressor and buying an empty 30 gallon tank. This would give me 10 extra gallons versus buying just a 30 gallon truck mount unit, and it would be significantly cheaper. Not sure if this is reasonable or if that cfm would suffice for my automotive tools?

Well that would depend on how far of a run it would be from say your dryer to where your compressor would be. You can make a extension cord with a pigtail on the end to where you just unplug the dryer and plug in the compressor


Tony

 

[TonyJ]

Well that would depend on how far of a run it would be from say your dryer to where your compressor would be. You can make a extension cord with a pigtail on the end to where you just unplug the dryer and plug in the compressor


Tony

And I’m actually doing that currently myself while I’m building my garage. I’m using a sanborn vertical 5hp 80gal compressor with 50ft 8/2 wire with a pigtail on the end as my cord and for 3 weeks now using it everyday it’s not tripped the breaker or anything.


Tony

 

[alex123]

Well that would depend on how far of a run it would be from say your dryer to where your compressor would be. You can make a extension cord with a pigtail on the end to where you just unplug the dryer and plug in the compressor


Tony

It would be at least 20'. But then the question remains of what will my next rental unit look like? I've actually just moved out of a unit that had no washer/dryer on site and I was going to the laundromat. Yes, 220v is definitely the best option in most cases.... I'm not sure it's the best long term solution for me. What are your thoughts on grabbing a 10gallon gas compressor and adding an external 30 gallon tank for 40 gallons total at 12.5 cfm. Do you think that would suffice?

 

[TonyJ]

It would be at least 20'. But then the question remains of what will my next rental unit look like? I've actually just moved out of a unit that had no washer/dryer on site and I was going to the laundromat. Yes, 220v is definitely the best option in most cases.... I'm not sure it's the best long term solution for me. What are your thoughts on grabbing a 10gallon gas compressor and adding an external 30 gallon tank for 40 gallons total at 12.5 cfm. Do you think that would suffice?

Myself if it was me I’d weigh your life and what your wanting to do as far as your working on cars and stuff to what kind of place or places ( future) that you might be getting. If the place doesn’t suit your needs then find somewhere else that does. I would bite the bullet of a 220 one and make the cord at your current place and if and when you move again then go to a place that will accommodate you better.


Tony

 

[sberry]

I be wiring g me up a circuit so neat no one even give it a second thought that it wasn't always there.

 

[rustedgoat]

In these rental units is compressor noise going to be an issue, like neighbors in an apartment or somewhere with an HOA? Is the compressor able to stay in one place or do you have to move it in and out of storage when needed?

A 6 gauge or thicker extension cord like the ones people use on welders might work, but but you need to check the startup amp draw.

I found electric tools work better for me. But for painting or sandblasting I needed the stronger compressor. I just put my compressor close to the fuse box in my basement, and run line to the garage when needed.

 

[sberry]

Neighbors will like engine drive even less. It's an expensive way to get shop air.

 

[TonyJ]

Neighbors will like engine drive even less. It's an expensive way to get shop air.

But in the OP’s case it would be totally portable. Only he can decide tho what’s the best option for today and future use


Tony

 

[redmondjp]

You only need a 12 gauge cord for most 3HP 240V air compressors. I have one plugged into my dryer outlet and it's been running my 3.3HP 60 gallon air compressor just fine for the past 22 years. If it makes you feel any better you can go with 10 gauge so it matches up with the 30A circuit protection. 3HP motor at 240V draws 15-16 amps, at least mine does.

I wouldn't bother trying to parallel anything at this point. I would start with one compressor and see how that does for you. If anything, get a secondary tank charged up to 130psi so it will look like a larger compressor initially when you pull the trigger.