Vacuum ?'s

[goodbasil]

Many vacuums are sold by horsepower ratings, which doesn't mean a lot. So the needle on some tester touched the 6 hp mark for a split second. Truth is, about 1.5 hp is the maximum you can get out of household power.
My vacuum will pull 200 cfm. So a container thats 5' x 5' x 8' high is empty in 1 minute. That measurement I can get my head around.
I'm told that. "inches of lift," is the way to measure a vacuums power. Is there a formula to convert cfm to iol?

[Pernicious Atavist]

This is similar to what I used when evaluating industrial vent systems in a nuclear lab:

Imperial Units

The velocity of air in a ventilation duct can be expressed in imperial units like

vi = qi / Ai = 576 qi / (π di2) = 144 qi / (ai bi) (1)

where

vi = air velocity (ft/min)

qi = air flow (cfm)

Ai = area of duct (square feet)

di = diameter of duct (inches)

ai = width of duct (inches)

bi = width of duct (inches)

Imperial Units Air Flow Velocity Calculator

Air velocity can be calculated with the calculator below. Add air volume - q - and diameter - d - (or length a and b).

Air volume - qi - (cfm)

Diameter - di - (inches)

or alternatively

Length side - ai - (inches)

Length side - bi - (inches)

SI - Units

Air velocity in a duct can alternatively be expressed in SI units like

vm = qm / Am = 4 qm / (π dm2) = qm / (am bm) (2)

where

vm = air velocity (m/s)

qm = air flow (m3/s)

Am = area of duct (m2)

dm = diameter of duct (m)

am = width of duct (m)

bm = width of duct (m)

SI Units Air Flow Velocity Calculator

Air velocity can be calculated with the calculator below. Add air volume - q - and diameter - d - (or length a and b).

Air volume - qm - (m3/s)

Diameter - dm - (m)

or alternatively

Length side - am - (m)

Length side - bm - (m)

[Pernicious Atavist]

Oh, the site: http://www.engineeringtoolbox.com/ductwork-equations-d_883.html

[JimConlin]

In addition to pure such power, there are a few other variables in shop vacs that that might matter.
Some are MUCH quieter than others.
Some have bypass fans, so that if the sucker is stalled, there's still air flow through the motor. If you use your vac for vacuum bagging, you won't fry the motor.
Some have relays so that you can use the vac with a sander and have it be controlled by the sander.

In these features, the Fein and Festool sanders are standouts. They suck, too.

[goodbasil]

Can't afford a Fein or Festool.
Mine is a Craftsman from Sears. Canadian made. The best one from Craftsman now is a 197 cfm, Chinese made job.

[Jim Ledger]

From a purely empirical comparison, Fein and Festool are fine machines for hooking up to a sander or power tool, but for heavy vacuuming of shop and construction debris, a Craftsman or Rigid vac is a better choice, IMHO. The former sport 1 1/2" diameter hoses, the latter 3", in addition to better suction.

[RodB]

I use my Festool mostly for tool dust collection (sanders mostly)... the degree of suction is adjustable etc...

In the shop, the 16 gal Sears craftsman is real powerful... with a removable motor unit that makes a really powerful blower with the blower nozzle. It sure blows out the garage in a minute or so. I use it like an air hose to blow dust off of me or the shop.

If you want a quality portable (the one I use when working on boats), the shop vac portable at lowes is hard to beat.

http://www.lowes.com/lowes/lkn?action=productDetail&productId=127133-20097-5872411&lpage=none

THis shop vac has great features and power for the basic needs of boats... vacuuming up some water or just getting the dirt... The blue model at Lowes is the best of its variations cause from Lowes it has a guarantee of 3 years. In other markets Shop VAc sells a red and also a yellow version of the same unit... with slightly less horsepower and less warranty time. Its hard to beat this unit when you need to carry a vacuum with you on boat working days... .and it works fine in the shop too.

Good luck.

RodB

[stevedwyer]

I found the small portable Rigid "pro" works with the Festool sander hose.
The problem with the Rigid alone is hose shrinkage. ( I hate that... ) The hose, rated a 7 ft wants to retract persistently to 2ft.
And the extension hoses they make aren't very good for a working hose, i.e. with power tools.
That's where Fein and Festool have the lip-lock.

[J P]

I had a Craftsman vac. Maybe it was just that machine, but what an obnoxiously loud high pitched screaming thing. It killed my dog. Literally. I had an old Jack Russel that had been deaf and pretty much mute for several years. He was laying on the couch sleeping and I brought in the Craftsman to do some cleaning thinking it wouldn't bother him since he was deaf. A few seconds after running it the little guy jumped up screaming and took off on a crazed full speed run. Wouldn't stop, just screaming and running and I couldn't catch him. He was 17 and hadn't run like that in years. Eventually he took off down the road and I had to hop in my truck to try and get him. 3/4 of a mile later I found him collapsed in a seizure, still running. Never came out of it. Had to put him down. :( ... and that really sucked. (hey, this is a vacuum thread)

Gave away the Craftsman, bought a Fein. I like the quieter Fein routers too.

[paladin]

I have the big sears wet or dry shop vac and use it for everything...for at least 15 years, and it's still running...

[TimmS]

I went Festool after my cheap one died - Ct 22 http://www.festoolusa.com/images/featureviews/583366-Front.jpg

how have it plus a 4" system for the planer, etc. As tools wear out or die, I'm replacing them all with festool....so far a drill, 2 sanders, the Domino (which is awesome), and the dust extractor. I love them.

[goodbasil]

ShopNotes did a bit on how to build a muffler for your vacuum, a few years ago. (Yes, they are noisy.)

[Tom Robb]

There's lies, damned lies, statistics, and finally electric motor horsepower ratings:rolleyes:

[coelacanth2]

I've a Fein MINITURBO for light duty cleanup and attachment to the sander, etc. and a big Shopvac for the heavy duty stuff. The shopvac has a muffler built in and is a good deal less noisy than the last few shopvac type things I've had. The most powerful was made by Genie (the garage-door lift folks!) that really sucked, but was painful to use due to it's ear shattering wail. I occasionally regret not getting the bigger Fein but this one's perfectly adequate. now, if I could only get the big vac. back from the fellow I lent it to...:D