How I Figure CFM of Air Compressors
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- Опубликовано: 4 окт 2024
- NOTE** Please read the pinned comment AND my reply to it to acknowledge what was a mistake in the spoken calculation. Thank you.
Volumetric efficiency is not the proper word for the technique described in the video, but it makes me sound like I know what I am talking about. But what I am really doing is verifying or testing to verify the actual output in cubic feet of air per minute (CFM) of an air compressor pump.
The calculation is simple once you think about it but the key is the multiplier used for the formula. That multiplier is .536 and it is used no matter what the tank capacity. The rest is quite simple and it works every time. If you have the rated CFM of the unit this process can be used to simply verify that you are getting what you paid for.
#figureCFM, #twostagecompressor, #industrialaircompressor
683 seconds is 6 minutes and 23 seconds? I don't think so
Yeah, I was trying to recall my earlier calculations without any notes...its 383 seconds. So that threw my calculation off if you are to use that 683 seconds in the calculation for this unit. Thanks for catching that... At least the formula is correct, but it relies on doing the math correct, which I DID on the paper calculation. That's why the video ends verifying the compressor as good. Good ear and thanks again for pointing that out. That's the cool thing about the youtube viewers...check and balance. I get caught from time to time with similar slips of mind.
Btw, I pinned this comment and added an addendum to the description on the first line.
Wow Mr Wendell, the technical info here you shared!! That is amazing!! I really enjoy hearing you speak about wiring as well, that's a passion of mine in a past life!! Thank you sir for another great informative video !! I really do enjoy these!!!
Thanks Nelson, you'd probably enjoy the home made 3 phase rotary converters then I'd bet. One of these days, I'll be hooking one of them up for the 3 phase equipment I have in the shop so I don't have to buy so many variable frequency drives.
@@tractorman4461 Man yeah !!! I can't wait to see those!!! You are a genius!! Thank you Mr Wendell
@@Pennies_on_the_dollar Oh oh....keep that up and I'll have to go to a bigger hat size...LOL Have a wonderfully productive day my friend !! Stay cool !!
@@tractorman4461 😁😁👍👍
Yet another very useful video, I will try this on my compressor, thanks for sharing Wendell
Well Raymond, I wish you luck with the calculation. The thing of it is, its easy to do two or three times to double check your figuring.
This is probably the BEST explanation I have come across after searching alot of YT videos! Thank you doc!
It's probably not the perfect way to do it but it is close enough to get in the right ballpark. The variables that effect it are the human aspect of monitoring the time frame and the inaccurate pressure measurement... (lack of digital components) and computer control. But that would be up to the factory engineers for that level of accuracy. Thank you for the candid comment today !!
Wendell, you are one smart fella with real world applications. A rare thing these days. Thanks for the video and laying out the process.
Thank you for the kind comment buddy...I'm just glad there's those viewers like you that enjoy the silly stuff I do here every day !!
very cool way of doing it, not many people use that method
For a non-laboratory or shop tear-down approach Mark, it does let you know if your compressor is still operating in the same ball park its supposed to be in.
Nice to know! Actually I used your formula to check my air compressor! Very easy to use this formula!
Yes, but remember to do your math correctly. LOL I had to admit that I'd made a mistake in trying to recall my figuring instead of looking AT the figures. But the formula is spot on when done correctly. Thank you for stopping in for a visit today.
You never cease to educate us.
Who'd a thunk all the math, geometry and algebra would come in handy......right...?? LOL
Very interesting Wendell.
Good Morning buddy !! Thanks for watching. Hope you find the day warm enough for your liking my friend. LOL
@@tractorman4461 ... and then some.
Outstanding informative video mon ami and you are very strong in maths ; ) Cheers !
Is math the same in French or does that language have different numbers.....LOL Just kidding Dave. I'm not that good in math, its just that numbers only add up correctly one way .......
@@tractorman4461 LOL ; ) Keep up your calculus Sir Cheers ; )
Very cool video! Thanks for the formula. 👍👍👍
You can tell when a belt is slipping by the squeal...but you can't tell too good how bad the rings or cylinder are worn. This kinda gives you an idea what's going on in there....
Love how Math's and mechanics meet each other, that's why History of the world at school was not my favorite subject, it don't help me to work with a tractor and implements lol, very informative my friend
Thanks Jan. If only they would tell us as students WHAT math can do in job applications. When I was in high school geometry, I had not idea how much geometry I would use in sheet metal later in life. It took me a long time to realize how much it helped me in layout. It's ALL in the numbers !!
Good evening Wendell.
Wow … yet again you teach and old dog a new trick.. My compressor is a 60 gal tank with a single stage..
125 psi maximum 11.4 cfm @40 psi-9.0 cfm @ 90 psi.
The one thing I have never like is it runs down to 40 psi before it kicks on and that is a pain when you run air tools.. But I have lived with it for over 30 years . I have not figured out how to change that..
Guess I will have to run that test ..
Thanks for the information.
As always stay safe and always be kind.
Cheers my friend..
On several home built units Gus, I used ole refrigeration controls that has an adjustable 'cut in' and a differential to adjust for the 'cut out'. They were common to almost all R-12 and R-22 refrigeration systems and readily available to service techs like me because we changed out systems continually. I think the manufacturers use tricks with numbers to figure cfm sometimes. I don't know exactly how they figure it. Kinda like the hp ratings on a vacuum cleaner or a table saw. Good luck with the calculations. Remember the .536 multiplier first !!
Ya got me, I did not know this calculation before. I need to know this information as I have a couple of compressors that were given to me recently, and I want to use them in my shop too.
Thank you for this one Wendell.
I forgot to point out that you can easily figure out what a 'shop built' or 'home made' air compressor is putting out. I still have the first system I ever built when first married. It's a belt drive refrigerant compressor out of a 1940's commercial cooler piped into a 60 gallon DeLaval vacuum tank mounted on a shortened riding mower frame. I still use it occasionally.
@@tractorman4461 Good stuff. I have one too, but built up with and from actual air compressor parts. Kellogg 80 gallon horizontal tank, belt driven Compair 'pump' powered with a 2 HP Leeson motor 220VAC 1 ph. Still using that one today too. Although, I think that tank is due for replacement, we'll see :)
Keep movin' along Brother!
Cheers!
@@regsparkes6507 Sounds like a much better unit than the first little one I built. LOL It's pretty important to blow them down ever so often too. People don't realize just HOW much water collects in the bottom of the tanks. I've installed dozens of automatic blow down solenoids on commercial compressors over the years.
@@tractorman4461 I used to try to impress this upon my customers too. I told them to look under their car after driving on a warm day, " see that puddle of water, that's condensation from your air conditioner,. This condensate is exactly what's happening inside your air compressor tank, so drain it daily, if you use the compressor each day, then if not, drain once a week."
P.S. Most of them did NOT listen, this is where I got the large air compressor tank from, a customer decided to have a smaller compressor installed. He was certain that a smaller tank wouldn't have as much water in it. D'uh! Gotta love those 'intelligent' ones!
@@regsparkes6507 Hahahahaha....that customer was too smart for his own good. LOL In addition to automatic blow down solenoids, in buildings with pneumatic controls we had to run the compressed air through a refrigerated air dryer to condense the moisture out of the air before it got the chance to contaminate the pneumatic thermostats, controls and actuators. Many times over the years the air dryers would fail and the system would flood with condensate ruining much of the control system. Pain the the rear !! People just don't realize just HOW much moisture is in the air on a hot and humid day.
Good Morning TM44 Friend! Another Adventure Vid for another CuppaJO aimed your way so Thanks for providing a 44 doughnut with another juicyJO! Jenny spent the day packing boxes, organizing family records, photos and letters into larger envelopes. Quite a chore we’ve been working on. She said she wanted to leave early but she was up late working hard. I packed up a good mess of family items, glass, ceramic and metal things from Grandparents, G Grandparents and GGGrandparents. She didn’t know the history of many items I’ve had in the cupboard to get out there one day. Can’t get much on a plane. And if they decide to search luggage stuff can break. Four years ago we went out to Portland and on our return flight I was chosen to be searched! I did ask why and the guard said because I had on an over shirt. Of course I asked why the X-ray machine wouldn’t pick up something. Well he was training a youngin so he zeroed in on DaveyJO! I have to check your groin Sir, the kid said. Oh Lovely! I though about saying, now don’t fall in love with me kid, I don’t go both ways! But I thought better of it thinking that could lead to a strip search! It was bad enough getting felt up where my doc does at physicals but with an audience? As all this was happening and the old guy was searching my carry on bag with a stern look on his face, got my shoes again of course. But this morning, just before I watched your adventure vid, I grabbed my handful of pills and my water to chug down all those big pharma nuggets, it’s a travel mug I use for water and there was a stink bug right at the opening! Well if you’ve had experiences with stink bugs you know they will spray you with stink bug defense solution when threatened. He plum did that in my mouth, my pills and me bread and I swallowed! YUCK YUCK YUCK said Me with a few choice other words just for drama and therapy prevention! After some mouthwash and a few more teeth brushings I rid meself basically. So, I managed to provide some drama and enlightenment when I was just Thanking you for my morning JOvid. Go figure, eh? I recon I’m just a story teller of sorts as you are I do believe. But ain’t all those stories a delightful desert of living happily? I didn’t run across that pic of my Uncle and Grandfather using the buzz saw cutting firewood but when I do it will be sent to the 44Ranch email pronto! Jen isn’t up yet but when she rises I’ll have her CuppaJO ready! Vitamin J is best when traveling and rising up for the day and through out! Well, I’d best git before another story comes to my huge mind with the 3” skull that houses it! Have a Super Fine as Frogs Hair day with Squeezes for The Mieezez! DaveyJO tippin and sippin your way!
Always a good chuckle with your stories DaveyJO....I gotta tell the Missus about the stink bug this morning. LOL So funny. I've never been searched, but then again, since 911 I almost always wear a USMC shirt of some kind. You'd be surprised how that gets the inspectors in conversation. Not all the time, but some for sure. I ain't EVER been violated as good as you did in Portland though !! Yes, best to keep the funny stuff to yerself when they up close and so personal... LOL Safe travels to Jen and safe JOdrinkin' to YOU. At least you didn't suck the stink bug down with the feel-good pills. Now THAT woulda been bad, especially if he stuck halfway down the hatch !! Take care and have a nice day my friend.....All the best to you, Jen and Alice this awesome day....
I'll have to try that on mine. Thanks Wendell.
One thing about it Glen, its easy to do two or three times to double check your figures. All the smart phones have the stop watches too and it makes it easy.
Thank you my friend. Great tips and how too as always. All my very best, to you and yours.
Glad you enjoyed it Bobby. It was a quick and fun video to do !! Take care and stay cool in this nice war snap....
Good stuff Wendell. I need to do that test on my air compressor. It's an older 60 gallon that is set to shut off at 125psi. It can't keep up with a 1/4" die grinder which I run at 90psi.
Well, rings and cylinders DO wear Matt. Lots of hours at high rpm and intense heat is rough on them. Regular oil changes are important. This is a very easy test of the output.
Hey buddy good job you are better than a calculator with all those numbers lol I think you was better in school than this one guy take care have a great day
LOL.... I don't know about that Tom. Hahahahaha... If I' have known just how much I was going to use math of all kinds for a 40+ year career in hvac, I think I would have payed better attention.
That could really come in handy! Thank you sir.
Thanks Curtis for the visit today. It's real handy for the guys that piece together their own systems in their shops. I've put together one or two over the years. LOL
Thank you 😊
Well, I hope it helped you get an idea to get in the ballpark of your delivered cfm. It might not be as accurate as rocket science, but it close enough for the average DIY homeowner.Thanks for the visit today.
Now that I have the calculations I have to go in my garage ......do the calculations and then announce to my wife that we have a bit of a expense coming......like changing the compressor.....It’s running good enough for this old guy.....not going to happen.....CHEERS
Hahahahaha....I understand that for sure !! I got a lot of stuff that's worn down a bit but still good enough for this old guy too !! LOL On a good note, most compressors of any size still have piston/rings sets, gaskets and valve plates available. Especially so for name brand units.
funny you mention 17 cfm, that's exactly what I got. However, it's supposed to be 22 cfm. When I calculate it out including the variables of my altitude, temperature, and current atmospheric pressure I get 21 cfm which I believe to be the most accurate I'm going to get. I built the machine myself, so there's no factory numbers to go off of. It's one hell of a compressor built on a trailer for blowing out sprinkler systems.
Well now, that's much deeper than my abilities will allow me to dive. It stands to reason there are those variables in play, I don't know how to account for them. Here's a sandbaster I built many years ago running behind a tractor that's too small to do the job: ruclips.net/video/VXuEXSUPPTU/видео.html Thanks for watching and chiming in with additional input today. A reminder for you to not look too deep in my projects as I am a 'seat of the pants' kind of guy. (-:
To convert gallons to cubic feet the factor is .133. (Gallons x .133= Cubic feet of volume). Where are you finding .536? Volume x pressure/ time to fill = Cubic feet per minute
.536 is an engineering constant for the specific purpose of calculating compressor CFM. The formula is:
CFM = G x 0.536 x PSIG / S
CFM = Cubic Feet per Minute of Compressor
G = Tank capacity in gallons
PSIG = Gauge pressure reading on tank
S = Seconds to fill tank
This is from a Mechanical engineer I worked with for quite a few years and what I would use to determine if compressors capacities diminished between preventive maintenance schedules. We kept records for the life of the units providing copies with our service reports to the business owners. I think we are doing the same thing though.
Engineers seem to like to make things more 'interesting'.
@@tractorman4461 I believe the constant is derived from, roughly, (.13368 * 60)/14.7 ---> This is (gallons to cubic ft conversion factor * 60 seconds)/atmospheric pressure in psi. Using these numbers you would get .5456, so just a hair off. My guess is the constant .536 is used as an "average" since atmospheric pressure changes over time. BTW, I calculated your compressor at 19.6CFM which seems more reasonable considering the industrial quality, motor HP, and dual stage. Nice comp ;)
👌
Thanks Jeremy, for watching. Stay safe today.
👍👏👏
Thanks Tony for the applause !! LOL
Are there any tools that will allow me to check SCFM in a machine?
I'm would think that there is...but I really have no idea for sure. Engineers have a formula for everything though. The only difference between SCFM and CFM is the conditions under which the calculations are made. SCFM is essentially done at a specific temperature and humidity with the actual unit and not with calculations. I'd think CFM is done the same way except in 'real world' conditions at your shop that is probably NOT going to be at their specific temp & humidity for SCFM.
Hi mate....is that value of cfm you came up with what you get at the outlet of the compressor ...like free air delivery....??
Yes, as far as I know, based on the size of the tank, a specific pressure for reference, and the time it took to get to that pressure, it should be darn close the the actual air delivery in cfm out of the discharge port of the compressor. However there are many ways the manufacturers manipulate their figuring to make something appear to be something its not.
@@tractorman4461 AvE did a video on said manufacturer manipulation ruclips.net/video/cfjSm_ieRkE/видео.htmlsi=AVVQapbS5XIqEuJm
Industrial Air in Sanborn, or Springfield Minnesota ? if it is I haven't seen one of those in a day, or two. Thank you.
You know Bryce, I didn't really look that close at the tag. I was mainly concerned with amp draw. One thin for sure it IS a good high quality American made air compressor.
@@tractorman4461 They are still in business under Minnesota Air Tool. I know a daughter, and husband of the original owner. Hauled for them 20 years ago.
@@brycewiborg8095 Awesome information Bryce !! Thank you, I appreciate that. I will look them up, I'm sure they'll be on google.
@@tractorman4461 I did a quick search. They air operating under Sanborn Mfg which was their original name. For a while they built generators in Kearney Nebraska, and hydraulic rams in Mountain Lake Minnesota. The company I drove for in the 90s was contracted to deliver 60 % of their equipment. That is why it caught my eye.
@@brycewiborg8095 So cool. Thanks again for the additional information. At least I knew the compressors are still being produced today though.