How many CFM do you need from an air compressor for a blow gun?

[jasonrohrer]

I need compressed air in my basement wood shop, mostly for a blow gun to clean the HEPA filter on my Oneida dust system. They recommend blasting it from the outside periodically with compressed air, to knock the dust off inside and let it fall in the dust bin attached to the bottom of the filter.

I have a commercial air compressor in the garage which can do 10.2 CFM @ 90 PSI, and it has a 60 gallon tank (5hp motor). I've been happy with this compressor for running air tools, running a nailer, filling tires, and for blow guns (including a Tornador for auto detailing).

I'm looking at a quiet wheeled compressor from California Air Tools, but they seem to top out at 5 CFM or so.

Would this be good enough for a blow gun in my wood shop? Or would I find that I'm running out of air constantly? For example, it might take me several minutes of continuous blowing to clean my HEPA filter from the outside.

 

[signcrafter]

How big of a tank does it have? Tank size will be what you have until compressor kicks in and then compressor will be doing the majority of the work. How often are you needing to blow out your filter. I would think 5CFM would be decent depending on the size of the tank. If anything you can blow for a while and then let compressor catch up and then finish. Guess it will come down to how often you need large amounts of air vs how quiet you want your compressor.

 

[whateg01]

Bigger cfm and bigger tanks let you use the blow gun for longer. But you could still use what you have to do the job. You'd just have to stop when the pressure gets too low and let the pump catch up.

 

[mike93lx]

A small compressor will not run a blow gun for that long.

I'd wonder how much pressure you really need. I'd be inclined to hit the filter with a shop vac and brush attachment first, then use a blow gun with the pressure turned down for the last bit.

 

[whateg01]

A small compressor will not run a blow gun for that long.

I'd wonder how much pressure you really need. I'd be inclined to hit the filter with a shop vac and brush attachment first, then use a blow gun with the pressure turned down for the last bit.

I couldn't get a leaf blower to dislodge the fines on our big dust collector this past weekend. It would get some, but not nearly all of it. I do agree with turning down the pressure or at least not holding the blow gun right up to the filter.

 

[zimman]

I have a 165psi craftsman with a 30 gallon tank and use it to blow off everything. CFM may be important for air tools but a blow off gun is just air moving. You might damage a HEPA filter with too much air I would think.
Zim

 

[mike93lx]

I have a 165psi craftsman with a 30 gallon tank and use it to blow off everything. CFM may be important for air tools but a blow off gun is just air moving. You might damage a HEPA filter with too much air I would think.
Zim

All tools are air moving... And a blow gun can run through a lot of it.

 

[mikedodge]

I have a little 5 or 7 gallon air compressor, dont know CFM but it's not much and has no problem using an air gun continuously for that sort of use. They don't need much cfm.

 

[whateg01]

I have a 165psi craftsman with a 30 gallon tank and use it to blow off everything. CFM may be important for air tools but a blow off gun is just air moving. You might damage a HEPA filter with too much air I would think.
Zim

If you hold the blow gun open for awhile, it'll deplete a tank eventually, no matter the size, unless the pump can put air in faster than it's letting it out.

 

[zimman]

If you hold the blow gun open for awhile, it'll deplete a tank eventually, no matter the size, unless the pump can put air in faster than it's letting it out.

Why would you do that. I'm not drying my laundry. LOL It takes 15 seconds to blow the dust off my clothes to go into the house.
I'm apparently out classed here. Several minutes to clean a filter is good reason to just toss it.
Zim

 

[whateg01]

Why would you do that. I'm not drying my laundry. LOL It takes 15 seconds to blow the dust off my clothes to go into the house.
I'm apparently out classed here. Several minutes to clean a filter is good reason to just toss it.
Zim

Dust collector filters can be pretty big. Those on the dust collector I cleaned this week are about 18" in diameter and 5 feet tall. A little puff of air here and there doesn't do it.

You don't just toss this when it gets dirty.

 

[Stevettt]

...Several minutes to clean a filter is good reason to just toss it.

Or perhaps just to clean the filter more frequently

 

[mike93lx]

Why would you do that. I'm not drying my laundry. LOL It takes 15 seconds to blow the dust off my clothes to go into the house.
I'm apparently out classed here. Several minutes to clean a filter is good reason to just toss it.
Zim

Who suggested tossing a filter?

 

[T444e]

I'm looking at a quiet wheeled compressor from California Air Tools, but they seem to top out at 5 CFM or so.

Would this be good enough for a blow gun in my wood shop?

What is the flow (CFM) of your blow gun? The manufacturer should publish this information. Then compare it to the capacity of the compressor you want to use.

 

[finn]

I typically use a blow gun in five or ten second bursts….maybe thirty seconds at an extreme.

I’m not cleaning six foot filters, though.

Never had an issue even with my forty five year old Craftsman 2hp compressor and twenty gallon tank. My little pancake compressor is even used occasionally to clean chainsaws of bar oil impregnated sawdust when changing or sharpening chains.

The California Air should do fine. Worst case you have to wait a couple of minutes for it to catch up. Unless you’re running some sort of production shop, that isn’t really an issue is it?

 

[JKinAK]

I have a commercial air compressor in the garage which can do 10.2 CFM @ 90 PSI, and it has a 60 gallon tank (5hp motor). I've been happy with this compressor for

How far is the garage from the wood shop?
It would be nice to save the space and not add another noisy piece of equipment in the wood shop.
If logistically feasible, spend the money on plumbing in air from your existing compressor.

 

[jasonrohrer]

I plan to clean the filter after every time I use my wood shop. But even if I do that, it's still a big filter to clean, and if I really go around methodically up and down the pleats, it's going to take more than 15 seconds.

Yes, I will look at the CFM requirements of my blowgun, good idea.

And YES, I did consider piping in air from the garage.... but it's far enough away that it would require a lot of time/effort, or a lot of money for a plumber to do it (thousands, at least... plumbing has gotten expensive). And I've kinda decided that I don't need ANOTHER huge project in my life... I know this is Garage Journal, but...

Ordering a wheeled compressor would solve the problem with no effort and probably less money. And a wheeled compressor might be useful in other situations (like running a nail gun in the attic or whatever).

 

[Steve_P]

There are formulas for air flow thru an orifice online; and this will give you a conservative result. Measure the ID of your blow gun nozzle. Use the formula. You'll have the answer. You can always buy a blow gun with a smaller passage, or just wait.

This was my first selection, and doesn't have an "enter value" formula, but has a table

Discharge of Air Through An Orifice Equation and Calculator

The table given below gives the discharge of air through an orifice in cu. ft. of free Air per minute at atmospheric Pressure of 14.7 psia, and 70 °F

www.engineersedge.com

 

[jasonrohrer]

Yeah, I just reviewed some standard blowguns online, and they are all 10 CFM or higher (some are 16 CFM).

This is actually near the limit of my 5HP commercial garage compressor, and I do hear it running a lot when I use a blowgun a lot (like if I'm using a Tornador while vacuuming a car).

So I'm guessing that a 5CFM quiet compressor is going to be a big disappointment for extensive blowgun use in a basement woodshop. Piping in from the garage is definitely the way to go.

However, it will still take me a long time to get that work done, and I do need to use the woodshop now, and I don't want to abuse my filter in the meantime.

So I may need to get a small wheeled compressor anyway just to limp along for a while. Maybe I will discover that cleaning half the filter and waiting for the compressor to recharge isn't that bad...

 

[mike93lx]

So I'm guessing that a 5CFM quiet compressor is going to be a big disappointment for extensive blowgun use in a basement woodshop

At full pressure, absolutely.

I have a 4.6 gal cat compressor and it will run out of air very quickly I hold the trigger on a blow gun

 

[Leaflessshadetree]

For that type of think I have a blow gun with a venturi nozzle. It moves a lot more air than my regular ones.

 

[ecotec]

Maybe you can find a cheap compressor at an estate sale to use just in the basement.

Other than my blow guns and air chuck, the tool that I still use a compressor for are air hogs (DA sanders, air hammer, polisher…). I, honestly, don’t turn on the compressor very often anymore.

If the garage is right over your woodshop, the suggestion of running some pipe down to the basement is the best idea. You could upgrade your garage compressor in the garage and not have to listen to it whilst in the woodshop.

 

[tarbellb]

Seems like a lot of filter cleaning? You are probably exposing yourself to more fine particulates doing the daily cleaning vs just letting the system run and clean when necessary ??

 

[WWheeler]

Perhaps a leaf blower is a better solution. Oneida recommends it as an option.



That said, I never clean my dust collector's filter inside my shop. I roll the can it's in outside to blow it out. Mine's not a 6' tall unit like pictured in the video though. Still, if it was, I'd figure a way.

That dude Oneida shows cleaning his indoors without any sort of particulate mask or respirator is insane to me. Even when I blow mine out outside I wear a mask.

 

[larry_g]

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Have you seen this style of cleaner?

lg
no neat sig line

 

[Sumboodie]

I recently a new Vornado? Blow gun to replace the leaking $5 Napa junk bin special I've had for probably 15 years. I'm sure you've all seem them. Usually blue plastic.

Holy smokes does it output air over that cheap one.

It kills my 30 gallon, ~6cfm quick. Maybe 10 seconds before the pump turns on and it definitely can't keep up.

 

[whateg01]

In theory, all the fine particulate stays in the filter until you remove the little canister from the bottom of the filters so blowing it out inside should be fine. Oneida has a self cleaning feature on some of their models where it closes off the filter to the real world and blows air backwards through it.

 

[Shoreline_]

if you press the blow gun 5 minute per hour you are consuming an average of 0.16 cfm and if your compressor is 3 cfm, well.... you can understand where storage plays a role.

 

[jasonrohrer]

Yeah, I'd never clean the INSIDE of a filter in my shop. But blowing air from the outside shouldn't put dust into the air, assuming that the HEPA filter is a HEPA filter!

The filter came with a sheet of instructions that said cleaning it after each woodworking session was ideal, to prevent "thick resinous dust" from building up on it long-term, which would be hard to remove once it built up.

I.e., I just spent $4k on a killer dust collection system. From the factory, it's pulling really great CFM. I want to keep it pulling really great CFM at all my tools. I also want to take good care of it.

So.. I'm going to follow the manufacturer's instructions on this one. I will spend 2 minutes cleaning it at the end of every work session.

I know most people don't clean theirs. Most people also don't drain their air compressors. Heck, most people don't even change the oil on their cars!

Leaf blower is a great solution, and I did see that in the video. Not sure why my mind blocked that out.

The Stihl plug-in ones deliver like 285 CFM, which is an order of magnitude more than you can get out of any ordinary air compressor.

 

[Steve_P]

There are some "dusters" that use tool batteries. Maybe one of these would be a decent option?

 

[Citation]

There is a difference in the peak velocity of an air gun vs leaf blower but volume may be more important in this case.

That said, if you want to go compressor perhaps you could take your air gun to a friend's place if they have a similar, small compressor. I have two frequently used small compressors, one is a 26 gallon, ~6cfm belt drive that tops at 135 psi. The other is a 5.5 gallon CAT that pumps 2.3 CFM at tops at 115 psi. The CAT isn't to bad for limited air gun use but with the larger compressor I'm not sure I've ever over taxed the compressor keeping up with the gun. I have used it to inflate pool toys. Not ideal but better than hand pumping. However, my 20V B&D leaf blower is much better for that job.

 

[jasonrohrer]

Hmm... electric dusters are interesting. I don't like the idea of stuff with built-in batteries (like the WOLFBOX, which is impressively powerful).... but there is this plug-in duster that does 51 CFM and might just be made in USA:

DATAVAC® ELECTRIC DUSTER®

The MetroVac DataVac® Electric Duster® is a compact yet unbelievably powerful computer and equipment duster. Learn more about this electronic air duster.

metrovac.com

 

[jasonrohrer]

Whoa, Metrovac has lots of options in this category, all made in USA out of metal.

Their top-end blower system puts out a whopping 227 CFM:

AirForce® Blaster | Industrial & Personal Blow Off Systems

We offer quiet, efficient, and portable industrial blowers to remove fibers, dust, and debris from clothes, surfaces, or components. Shop MetroVac today!

metrovac.com

Granted, a Stihl leaf blower does 285 and is much cheaper, but the form factor there isn't really ideal for general-purpose indoor blow-off tasks. It would actually be too much to handle indoors, I'm guessing, blowing objects all over the place and stirring up dust from every corner of the room.