Thread Number: 34206  /  Tag: Recent Vacuum Cleaners from past 20 years
Rainbow E2 2-Speed Measurements
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Post# 370689   4/14/2017 at 11:02 (187 days old) by wyaple (Pickerington, OH)        

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In searching around YouTube, I came across two videos that appear to depict an airflow and water lift measurement for the E2 2-Speed machines. These seem to be accurate and show the machine achieving:

77 CFM at the hose end (not the nozzle end) and
74" water lift at the canister base (not the hose end).

If these measurements are approximately correct, what does everybody think about this level of performance for a modern Rainbow costing thousands? And if these measurements are incorrect, what should they be?

Airflow Link:

Water Lift Link:

For comparison purposes, here's the same readings from my D4C SE PE:
Water lift from base = 60"
Airflow from hose end = 60 CFM

So for the newer E2 2-Speed, that's an improvement of:
74" - 60" = 14" (23%) better at the base and
77 CFM - 60 CFM = 17 CFM (28%) better at the hose end.

Quite a nice improvement from the switched reluctance motor!

BUT, is this enough performance when other machines (read: cheap plastic bagged vacs) can do much better at a tiny fraction of the price?


  Photos...       <              >      Photo 1 of 2         View Full Size

Post# 370691 , Reply# 1   4/14/2017 at 11:10 (187 days old) by sebo4me (Cardiff)        

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Very average I'd expect a lot more for such an expensive vac! At least 90 CFM
A 100 would be better.

Post# 370693 , Reply# 2   4/14/2017 at 11:20 (187 days old) by wyaple (Pickerington, OH)        
Correction on my D4C SE PE's Airflow

wyaple's profile picture
it's 65 from the hose end, not 60. The 60 is from an older D4C SE.

So for the newer E2 2-Speed, that's an improvement of:
74" - 60" = 14" (23%) better at the base and
77 CFM - 66 CFM = 11 CFM (17%) better at the hose end.


I personally would expect more, yes...


Post# 370696 , Reply# 3   4/14/2017 at 11:30 (187 days old) by sebo4me (Cardiff)        

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I would still like to own one though as it's something different. I've never used a water vac before. They are very well built from what I've seen of them. I've seen a strip down. It looks quality.

I have a question for you Bill. Cyclones severely restricted airflow. The Shark rotator scores a 2 on the Baird meter. Yet the CRI give it a silver award which is quite a high standard and in the UK it get a Big award for carpet pick up which is very good.
How can it be getting such good ratings when the airflow is supposedly so poor? I'm confused! 🤔

Post# 370697 , Reply# 4   4/14/2017 at 11:31 (187 days old) by sebo4me (Cardiff)        

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B award*

Post# 370706 , Reply# 5   4/14/2017 at 14:09 (187 days old) by wyaple (Pickerington, OH)        
Taking A Brief Look at CRI's Rating System, I Found This

wyaple's profile picture
So based on the photo, CRI lumps vacuums into three very unequal categories for soil removal and only two very broad categories for dust removal.

For soil removal, they have these percentages:
Bronze = 40%-49%
Silver = 50%-54%
Gold = 55% or More

I have a BIG PROBLEM with those insanely non-linear and broad categories.

Soil Removal Example #1:
Vac #1 achieves 50% soil removal while Vac #2 achieves 99% soil removal. CRI would only rate Vac #1 as "Silver" and Vac #2 as "Gold" even though Vac #2 is nearly twice as good.

Soil Removal Example #2:
Vac #1 achieves 54% soil removal while Vac #2 achieves 55% soil removal. CRI would still rate Vac #1 as "Silver" and Vac #2 as "Gold" even though Vac #2 is only better by an insignificant 1% difference, which isn't statistically significant.

For soil removal, CRI can't tell the difference between a vac that does 44% better (the difference between 99% and 55%) while a measly 1% difference suddenly raises a rating from Silver to Gold. That is far too inaccurate a rating system for me.


Post# 370708 , Reply# 6   4/14/2017 at 14:19 (187 days old) by sebo4me (Cardiff)        

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Yes I've always thought that too. In the EU they have ratings from A to E for performance on carpet, hardfloor, filtration and energy.
For carpets an A rating picks up 91% and a B rating is 87% etc.

The Shark gets a B rating. The Dyson DC41 (DC65) gets a C rating.

Post# 370712 , Reply# 7   4/14/2017 at 16:02 (187 days old) by kenkart (Mocksville, NC)        

The new ones are much better than the older ones, but still are PLASTIC...Is there no one who can build a quality metal machine anymore!If I am asked to pay 2000 or more it better be metal.

Post# 370717 , Reply# 8   4/14/2017 at 16:31 (187 days old) by jimjimmunster (Hammond, Ind.)        
I bet my C would pull more....

jimjimmunster's profile picture
I'm disappointed at those rates as I thought it would do better.

Post# 370753 , Reply# 9   4/14/2017 at 21:56 (187 days old) by Blackheart (North Dakota)        
This is odd

I've got one of the Black E2 rainbows and mine with it's new style hose has never registered more than 2.5/10 BUT when i put an older style electric hose on it it pulled either a 4 or 4.5 at the hose end. It pulls even more with a straight suction hose and it leads me to believe that either the electric have a narrower internal diameter or they just have a rougher interior.

Post# 370765 , Reply# 10   4/15/2017 at 05:58 (186 days old) by Rainbowd4 (TN )        
D4 readings....

Wyaple it doesn't make sense that you're D4 se/pe would pull more than your D4 se. They are the exact same machine as far as the canister is concerned. The only difference was the hose with button lock, and trigger, and the new power nozzle. As for the 2 speed, I have the black, but I don't have a Guage. They have been measured more than once to have 90" of water lift, but I couldn't tell you what thread it was in. Tom gasko would know or remember more about it. Mine is extremely strong, but it does do a little better with a standard hose, as opposed to the electric. If you look in the machine end of the electric hose you can see that it has a small diameter, or so it appears.

Post# 370773 , Reply# 11   4/15/2017 at 07:36 (186 days old) by Mike811 (Finland)        
Not good...

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Being so expensive vacuum cleaner those results are not acceptable. I mean seriously 65 cfm from the hose end.
Even my bagless Electrolux Ultraflex pulls 85 cfm from the hose end and it has cyclone restricting -20 cfm of the airflow.

Post# 370778 , Reply# 12   4/15/2017 at 09:50 (186 days old) by dysonman1 (Rolla, Missouri)        

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The Baird meter is an extremely inaccurate way to measure anything. It was designed to make a Kirby look good and everything else look bad. I consider about useless.

They make digital air speed (wind speed) meters that are extremely accurate. For a true reading of airflow on any vacuum, you need a digital air speed meter. It will give the reading in MPH or Nautical MPH or CFM, which ever setting you choose. The Quality Assurance Department at Tacony uses them to measure the airflow through new batches of motors received at the factory, in addition to the engineering department's use of those meters to determine airflow through a complete machine, both with a clean as well as a dirty bag (half full bag of 'test dirt' from the cleaning ability tests).

Post# 370783 , Reply# 13   4/15/2017 at 10:44 (186 days old) by Mike811 (Finland)        
Manufacturer specs VS baird air flow meter

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Baird air flow meter has worked for me well enough.
For example it showed 9 = 109 cfm when I tested my Philips Performer Pro.
Philips says in their website that it has 51 liters/second air flow. It converted to the cfm is 108 cfm.
I would say it's quite accurate.


Post# 370787 , Reply# 14   4/15/2017 at 12:31 (186 days old) by wyaple (Pickerington, OH)        

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Glad to see that my painstaking, scientific Baird meter tests are repeatedly confirmed as being highly accurate! But, just for the heck of it, here's the graph I generated (using the GM8901 digital anemometer) that translates Baird readings to actual CFM again.


Post# 370788 , Reply# 15   4/15/2017 at 12:49 (186 days old) by wyaple (Pickerington, OH)        
Reply to Chris Post #10

wyaple's profile picture
It makes perfect sense that a 1993 Rainbow D4C SE with the older spider, older non-trigger hose, older motor, etc., would have 5 CFM less at the hose than the 1997 D4C SE PE. Slightly different parts and another 4 years of age takes it's toll. Also, don't discount manufacturing tolerances. If a factory makes 10,000 of something, they won't all measure exactly the same.

1993 D4C SE
Rainbow D4C SE water lift from base = 58" lift
Rainbow D4C SE water lift from hose = 54" lift
Rainbow D4C SE (measured at body)= 80.2 CFM = Baird 4.5
Rainbow D4C SE (measured at hose)= 60.1 CFM = Baird 2.0

1997 D4C SE PE
Rainbow D4C SE PE water lift from base = 60" lift
Rainbow D4C SE PE water lift from hose = 54" lift
Rainbow D4C SE PE (measured at body) = 87.4 CFM = Baird 5.5
Rainbow D4C SE PE (measured at hose) = 65.2 CFM = Baird 2.75


Post# 370790 , Reply# 16   4/15/2017 at 13:45 (186 days old) by sebo4me (Cardiff)        

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Bill doesn't just rely on his Baird meter he also has a digital anemometer. That's not easy to say after a few beers :)

It is very accurate!

Post# 370792 , Reply# 17   4/15/2017 at 14:15 (186 days old) by wyaple (Pickerington, OH)        
Here's What The GM8901 Digital Anemometer Looks Like

wyaple's profile picture
When powering up. Many, many things to choose from! It can even read the temperature of the air simultaneously with the flow (in many different units).


Post# 370819 , Reply# 18   4/16/2017 at 08:37 (185 days old) by criswan (The Internet)        
CFM Really Doesn't Mean Much

We demo'd several vacuums on our new carpet because our Kenmore Progressive wasn't cutting it. The powerhead just sucked to the floor and left the frieze looking matted and unkept. No amount of messing with height settings did anything. Our Hoover Platinum Bagged wouldn't even push across the floor. It came down to between a Rainbow E2 Black, FQ Majestic, and Kirby Avalir. I ended up buying all three because they were bargains, but the Avalir, though it has the highest CFM, is the poorest performer. It leaves sand behind that the FQ gets every time and it leaves hair behind that the Rainbow gets. I even bought the pet brushroll thinking that would improve it's performance. No go. A good powerhead and good airflow will overcome issues with suction everytime.

With many people going to low lying shag and the new soft carpeting types, the old benefits of suction may actually be the customers downfall. PS, best grooming vacuum we tried, Dyson Cinetic Big Ball, unfortunately I could not get past the no filter design and the amount of dust being left at the motor inlet after each use.

Post# 370820 , Reply# 19   4/16/2017 at 09:29 (185 days old) by sebo4me (Cardiff)        

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The Filter Queen performed better than the Kirby? Had you been drinking by any chance?
And it's airflow that gets the dirt into the bag. The more airflow the more dirt it will pick up. Of course you need agitation too.
I recently sold my Dyson. I've gone off bagless!

Post# 370821 , Reply# 20   4/16/2017 at 09:49 (185 days old) by sptyks (Woburn, MA)        

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Everyone I know says the Kirby Sentria - Avalir is the best performing vacuum cleaner on Frieze carpet by far. Either your Avalir was not adjusted properly or something was wrong with it. You can search the Vacuumland archives and you will find that Kirby beats everything else on Frieze carpet.



Post# 370824 , Reply# 21   4/16/2017 at 11:30 (185 days old) by wyaple (Pickerington, OH)        
Reply to Post #18

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Are you sure you understand the differences between CFM, airflow and suction? Your post seems to get them mixed up.

"CFM Really Doesn't Mean Much"

You do know that CFM is airflow, correct? Suction equates to water lift.

"A good powerhead and good airflow will overcome issues with suction everytime."

That sentence actually claims good airflow is better than good suction. Which is correct, but the Kirby has the best airflow out there.

It sounds like your new carpet is quite the nightmare. Were you aware that cleaning it would be such a hassle? It may be that the backing doesn't allow high airflow and is roughly the equivalent to a rubber backed mat, which all high airflow machines will have issues with.

If so, you would need a low airflow, high agitation machine that "floats" on top of the carpet, never making a good seal to the fibers. There are many machines out there these days that fit that bill.


Post# 370843 , Reply# 22   4/16/2017 at 21:57 (185 days old) by Kirbysthebest (Wichita, KS)        

I knew the older Rainbow had a cfm of 60. I had just assumed they had increased their performance by now. The less expensive Sirena moves 90 cfm.

Post# 370846 , Reply# 23   4/17/2017 at 01:22 (185 days old) by sebo4me (Cardiff)        

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Canister with Power Nozzle
Complete System: 10.9-Amp. (1285 Watts)
Suction Motor: Italian Amatek Motor (1200 Watts)
Revolving Brush: 12" Wide with Two Rows of Bristles
Brush Driven By: Electric Motor in Power Nozzle
Belt Type: Flat Stretch Type Belt
Suction: 86.3" of Water Lift
Air Flow: 63.556 CFM

Post# 370847 , Reply# 24   4/17/2017 at 01:29 (185 days old) by sebo4me (Cardiff)        

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That may not be correct though. It does say 90 CFM on the Sirena website.

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