Measuring CFM?

[blackheart]

Ha! I like that scale. Would have been a good sales tool.

 

[cheesewonton]

Many years ago my old local vacuum store had a suction meter similar to this shop down below. I remember back in 2012, my buddy showed me a demonstration between a Panasonic Platinum QuietForce MC-UG729 to a Sanitaire S645 Type A, it was a night and day difference. The Panasonic I think got a mixture of SORRY and POOR ratings while the Sanitaire went all the way up to the WOW rating. Despite that test, I still like the Panasonic more than the Sanitaire. I don't know who made those suction meters but I'd love to find one to play around with just for fun. I may not care much about the actual numbers but something like that meter gives me a better idea of just how much airflow any machine has on the nozzle.

Have a look at his video from Vacuum Wars where they test a selection of direct air and clean air commercial uprights. The Sanitaire Tradition had the highest airflow by far, but they have low sealed suction compared to the clean air machines. Not seeing the test you refer to I can't comment on the nature of the test procedure, how they measured sealed suction on a direct air vacuum with no hose, the test equipment used or the condition of the vacuums tested. This Vacuum Wars test is a test of new vacuums. My only criticism is the anemometer they use is not accurate, it reads overly high airflows, but for comparing machines it is acceptable.



I have a Hushtone and like it except for the lack of a synthetic HEPA dust bag. I have been fooling around with other kinds of HEPA dust bags to see what might fit the Hoover mount. Stay tuned.

 

[vaclab]

Try using a Kirby on the hose to dust with. Miserable. It doesn't pick anything up. 30 inches of sealed suction for my Avalir 2.

Miserable to dust with? That's crazy talk. 120 hose CFM picks up dust fabulously. And suction barely matters as I have conclusively proven since 2017 on my YouTube channel.

1) Suction is a one dimensional pressure, not a movement or a volume. Suction doesn't pickup anything (in the air).
2) Airflow is the speed of a volume of air and transports the dirt from point "A" to point "B".
3) Vacuums with little to zero measured nozzle suction can pick up dirt.
4) Airwatts are one of the many false attempts of manufacturers to sell vacuum based on useless data.

AirWatts Suction And Airflow Explanation


Congrats on your hotwire anemometer, but never forget that cheaper units (using fan blades) can measure CFM (indirectly) just fine. Are you aware that some of them have built-in functionality that actually produces a CFM number? I have one. I also have a super cheap model that requires one simple ratio calculation to convert ft./min to CFM.

If you want to see how to build a proper (cheap) airflow box and obtain accurate airflow/suction readings, check out my YouTube channel.

 

[vaclab]

Here's my fully measured TriStar CXL. It does have a 10-Amp motor in it though.

 

[cheesewonton]

Here is a great example of why those fan style anemometers are so inaccurate. You claim 132 cfm at the hose connection. The motor in a CXL cannot produce that much airflow. Airflow in a vacuum motor is dependent on the size of the orifice. Vacuum motors make maximum airflow at a 2 inch or 50 mm opening. As you reduce the diameter of the orifice airflow is reduced. The OEM motor in a CXL is Ametek 116884-49. I have the Product Bulletin pdf open for that motor and will try to attach it but no guarantees it will load. Anyhoo, the maximum airflow at a wide open orifice for that motor is 115 cfm. That's it. The hose opening on a CXL is 28 mm or 1.1 inch measured with my caliper. Looking at the Ametek Product Bulletin at a 1.125 inch orifice that motor produces 90.7 cfm. That is all the motor can produce. It is physically impossible for the motor in that CXL to produce 132 cfm at the hose opening. In fact very few vacuum motors that are safe to use on a standard household 12 amp circuit make 132 cfm at an unrestricted orifice much less at the tiny 1.1 inch opening Tristar, Miracle Mate and Patriot use.

Here is how to think about how airflow is calculated by an anemometer. Think of a long tube filled with some fluid. The tube is moving at a certain velocity. The volume of fluid passing a point depends on the size of the tube, its velocity and the time period. The only thing any anemometer measures directly is the velocity. But lets say you want to know the volume of liquid that passes by the anemometer in a given time. Airflow is measured in units of volume multiplied by time, cubic feet ( volume ) per minute. Imagine your tube full of liquid flowing past your anemometer. The anemometer only knows how fast it is going. The tube could be 1/4 inch diameter or 2 inches diameter and the anemometer could not sense the difference. But for a given velocity the 2 inch diameter tube will pass a lot more volume past the anemometer in a given period of time than the 1/4 inch tube. That difference in diameter matters. But for anemometers that are used for commercial HVAC, most of the time the ducts are square or rectangular, so the meter I have requires the user to enter the surface area of the opening ( imagine a square tube filled with air rather than a round one flowing past the anemometer ) so the anemometer can accurately calculate airflow. Those propeller anemometers use the surface area of the round opening the propeller sits in, but that opening is a lot larger than the diameter of any vacuum hose so the readings it gives for vacuums are wildly inaccurate and almost always too high.

 

[cheesewonton]

All of my various Tristars, DXL, EX-30, MG and my modified models ( different motors and in the case of modern Tristar bodies I hog out the plastic exhaust port so you can no longer connect a hose to it as a blower but I leave enough material to attach the exhaust filter ) produce the same airflow. 52 cfm measured at the hose end and this measurement is a bit higher than it really is due to the limitations of my anemometer mentioned earlier. I can use the 356 peak air watt OEM motor, a nice Electromotor replacement motor the 6500-298 rated at 438 air watts, or a modern motor from a Pro Team Supercoach backpack vac, the Ametek 119347-01 rated at 489 peak air watts ( and 140 cfm at a wide open orifice ) and it doesn't seem to change anything. They all produce 52 cfm at the hose end and low to mid 60 inch water lift ( boy you can hear the air hissing past the hose swivel on modern Tristars ! ). The only motor I have tried that gave a marginally better result was a Panasonic 3D Inducer motor from a Kenmore Elite, a 600 air watt beast that gives cfm airflows into the 70s on Kenmores. I modified a CS motor mount and put one in a modern Tristar body. On the Tristar it produces 56 cfm. Big whoop.

 

[vaclab]

Ohhhh boy, dude. Re-read my statement:

Today at 8:55 AM #24
Here's my fully measured TriStar CXL. It does have a 10-Amp motor in it though.

That's not the original motor! The original motor (6 Amps) would be MUCH weaker obviously.

Wanna see what a central vacuum grade motor (12 Amps) can do in an old canister? Check this out:

 

[panasonicvac]

Have a look at his video from Vacuum Wars where they test a selection of direct air and clean air commercial uprights. The Sanitaire Tradition had the highest airflow by far, but they have low sealed suction compared to the clean air machines. Not seeing the test you refer to I can't comment on the nature of the test procedure, how they measured sealed suction on a direct air vacuum with no hose, the test equipment used or the condition of the vacuums tested. This Vacuum Wars test is a test of new vacuums. My only criticism is the anemometer they use is not accurate, it reads overly high airflows, but for comparing machines it is acceptable.



I have a Hushtone and like it except for the lack of a synthetic HEPA dust bag. I have been fooling around with other kinds of HEPA dust bags to see what might fit the Hoover mount. Stay tuned.

VW's tests are so misleading, that's one of the reasons why I don't watch his channel anymore. Bill (VacLab) gives a more thorough explanation in his posts and videos which makes more sense to me.

 

[cheesewonton]

Ohhhh boy, dude. Re-read my statement:

Today at 8:55 AM #24
Here's my fully measured TriStar CXL. It does have a 10-Amp motor in it though.

That's not the original motor! The original motor (6 Amps) would be MUCH weaker obviously.

Wanna see what a central vacuum grade motor (12 Amps) can do in an old canister? Check this out:

View attachment 168395

All I am saying is that you are using an inaccurate anemometer to measure airflow. It is giving a false high reading because it is calculating airflow based on the diameter of that fan, which is larger than the diameter of any opening on any vacuum except for shop vacs with 2 inch hoses.

Tell us what motor you are using and I will dig up the data sheet for it and see if it can really produce 146 cfm through a 1 1/4 inch orifice. A Perfect C101 is the same vacuum as the Marquis other than their motors and motor housings and the Perfect thankfully doesn't have the automatic bag door "feature". You can literally swap parts between them and most aftermarket parts fit both. The motor used in the Perfect C101, Ametek 122093 is rated at 557 peak air watts, pulls 13.2 amps ( which is probably why they burn up wiring and connectors ! ) and is rated for a maximum airflow of 123.8 cfm. The C101 generates 77 cfm at the hose end on my anemometer. Unless I see a data sheet that says otherwise I am doubtful any 12 amp suction motor can generate 146 cfm through a 1 1/4 inch opening or 115 cfm at the end of a standard 1 1/4 inch hose.

 

[cheesewonton]

Btw, if you are using the 10 amp Ametek 115923 motor in the CXL, it's maximum rated airflow is 122 cfm at a 2 inch orifice. I have that motor in my DXL and all it gives at the hose end is 52 cfm, same as every other motor I have tried in one. And that is with no exhaust filter, just the little diffuser.

 

[vaclab]

cheesewonton,

If you are actually testing a wide variety of motors with significantly difference performance ratings and only getting 52-56 hose CFM there is a HUGE problem somewhere. You may have a very leaky hose (or some other catastrophic damage/leak) or you're not measuring correctly. I've been doing this for years and have made great efforts to match my numbers to actual OEM specs (Sanitaire, SEBO, Prolux, etc.). For example, the cheap GM8901 anemometer you see in my profile picture can give CFM numbers if you multiply the ft./min. by 0.026099. Through a series of adapters, one can easily attach any vane based tool to the vacuum/hose in question.

What really bothers me is when you falsely claimed:

"Try using a Kirby on the hose to dust with. Miserable. It doesn't pick anything up."

Kinda kills your credibility right there for a multitude of reasons. Kirby's have been picking up dust very well from the hose end for over 100 years!

Bill

 

[cheesewonton]

cheesewonton,

If you are actually testing a wide variety of motors with significantly difference performance ratings and only getting 52-56 hose CFM there is a HUGE problem somewhere. You may have a very leaky hose (or some other catastrophic damage/leak) or you're not measuring correctly. I've been doing this for years and have made great efforts to match my numbers to actual OEM specs (Sanitaire, SEBO, Prolux, etc.). For example, the cheap GM8901 anemometer you see in my profile picture can give CFM numbers if you multiply the ft./min. by 0.026099. Through a series of adapters, one can easily attach any vane based tool to the vacuum/hose in question.

What really bothers me is when you falsely claimed:

"Try using a Kirby on the hose to dust with. Miserable. It doesn't pick anything up."

Kinda kills your credibility right there for a multitude of reasons. Kirby's have been picking up dust very well from the hose end for over 100 years!

Bill

I have a low hour well cared for Avalir 2 I dote on and while it does an ok job on our big area rugs and with the dusting attachment attached to the bottom of the nozzle does a good job on hard floors, something I didn't expect but am happy about, it is not very good for above floor cleaning. I was surprised given the reverence for Kirby among vacuum enthusiasts but in our home with our caliche dust and pet hair the Kirby cannot match a good canister vacuum for dusting. The thing only generates 30 inches of water lift at the hose end, the lowest of any vacuum I have tested. It is inadequate. I had high hopes because the Kirby dusting brush is pretty nice but it left a lot of dust.

I have small high powered Japanese canister vacuums from Panasonic and Hitachi that run on 100 volts and they have vastly more suction and airflow than any Kirby. So does a good running Kenmore Elite or either of my big Swedish Luxes, the D795 and D820, that I brought over from Japan. All of these have more cleaning power than anything from Kirby. The little Japanese vacuums, bagged canisters with power nozzles, peg a BAIRD meter at the bottom of a fully extended wand. Even a Kirby can't peg a BAIRD meter at the end of their hose much less down at the bottom of the wand. And they peg that BAIRD meter with a loud click. That's power! That is what I am accustomed to using to dust with. I am not trying to offend anyone here but it is the truth.

 

[Vacuum Facts]

Ive been led to believe that even if a vacuum has high CFM it doesn't ensure success or offer best performance - again like air watts, its all about whether the vacuum in question has a sealed suction unit.

This is correct. Suction (pressure difference) is the critical aerodynamic parameter in a Venturi system that principally determines the acceleration of particles necessary for their removal. High air currents within these systems that act to reduce suction are actually bad and measuring volumetric air current into a machine indicates a common misunderstanding of the relevant fluid dynamics. I have a full lecture which details the formal science of how vacuum cleaners work in a way that I hope is accessible. I derive from first principles what physical parameters determine cleaning performance—which is what counts, and cover everything downstream, including filtration. Take a watch and if you need me to clarify any technical points, I can.

 

[panasonicvac]

I have a low hour well cared for Avalir 2 I dote on and while it does an ok job on our big area rugs and with the dusting attachment attached to the bottom of the nozzle does a good job on hard floors, something I didn't expect but am happy about, it is not very good for above floor cleaning. I was surprised given the reverence for Kirby among vacuum enthusiasts but in our home with our caliche dust and pet hair the Kirby cannot match a good canister vacuum for dusting. The thing only generates 30 inches of water lift at the hose end, the lowest of any vacuum I have tested. It is inadequate. I had high hopes because the Kirby dusting brush is pretty nice but it left a lot of dust.

I have small high powered Japanese canister vacuums from Panasonic and Hitachi that run on 100 volts and they have vastly more suction and airflow than any Kirby. So does a good running Kenmore Elite or either of my big Swedish Luxes, the D795 and D820, that I brought over from Japan. All of these have more cleaning power than anything from Kirby. The little Japanese vacuums, bagged canisters with power nozzles, peg a BAIRD meter at the bottom of a fully extended wand. Even a Kirby can't peg a BAIRD meter at the end of their hose much less down at the bottom of the wand. And they peg that BAIRD meter with a loud click. That's power! That is what I am accustomed to using to dust with. I am not trying to offend anyone here but it is the truth.

Both of my G4s' (one was my grandparents') did a fine job with dusting at my grandparents' house. Even better than their Dirt Devil bagless that has more suction than their G4 when I remember fitting the G4 dusting brush on the Dirt Devil to dust.