Thread Number: 34182  /  Tag: Brand New Vacuum Cleaners
Miele C3 Airflow Losses: Some Meausred & Some Estimated
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Post# 370433   4/10/2017 at 15:44 by wyaple (Pickerington, OH)        

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First off, thanks to Devin for providing the two actual measured readings. He works in a store that actually sells Miele products.

By The Numbers:
141 Motor CFM: This is provided by the manufacturer and reflects the maximum motor airflow when not installed into the machine body.

111 CFM at the canister base: After installing the motor into the canister base with all bags and filters, this is my estimation of the remaining airflow.

101 CFM at the hose end: This is the measurement taken with the hose stretched out as straight as possible.

95 CFM at the wand end: This is the measurement taken with the hose stretched out and the wands opened up to approximately three feet.

85-89 CFM at the nozzle end: This is my estimate of the airflow after passing through the final connections and u-joint at a 45 degree angle.

Total (estimated) airflow losses from the canister base to the power nozzle (held at a 45 degree angle to the floor) is 111-87(averaged between 85 and 89) = 24 CFM or about 22% of the original airflow. Of course as the bag fills, the airflow will drop in addition to more losses depending on how the hose is coiled.

Comments welcome of course.

Bill





Post# 370440 , Reply# 1   4/10/2017 at 17:41 by Tseg (World Traveller)        

There are lots of anecdotal stories that Miele bags excel at letting air flow as it fills. Not sure if the same can be said for other high-end vacs? It is like fuel economy ratings in 18-wheeler trucks that are tested with pristine engine oil... in daily driving most use basic conventional oil that gets great fuel economy the first 100 miles but thickens up quickly, destroying fuel economy the next 20K-40K miles before the next oil change. I'm curious what high-end vacuums are notorious for air-flow drop-off with 1/4 and 1/2 full bags, i.e. real world testing?

Post# 370442 , Reply# 2   4/10/2017 at 18:26 by wyaple (Pickerington, OH)        
Physics Says,

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HEPA material is HEPA material and it will lose airflow as it fills. BUT, as I have performed bag airflow loss tests, you don't lose that much. Think 15-20 CFM for a typical HEPA cloth bag.

Bill


Post# 370475 , Reply# 3   4/11/2017 at 10:31 by wyaple (Pickerington, OH)        
Tseg, Here's My HEPA Bag Airflow Loss Tests To Date,

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Cloth HEPA Bag Losses (Same dirt type in all three bags of course)

Hoover Tempo Widepath (Crucial HEPA Bag)
0% full = 114 CFM (Body) and 106 CFM (Hose)
50% full = 97 CFM (Body) and 90 CFM (Hose)
100% full = 99 CFM (Body) and 91 CFM (Hose) <-No, those numbers are not a mistake, dirt can shift in the bag slightly affecting results by a percent or two.

Electrolux Olympia One (Perfect HEPA Bag, new vinyl hose)
0% full = 102 CFM (Body) and 85 CFM Hose
50% full = 85 CFM (Body) and I donít have the hose measurement handy
100% full = 87 CFM (Body) and 79 CFM Hose

Kirby Heritage II Legend (Kirby HEPA Bag, new Amodel fan installed)
0% full = 161 CFM (Body) and 105 CFM (Hose)
75% full = 141 CFM (Body) and 105 CFM (Hose)
100% full = Didnít perform formal measurements but quick check yielded no appreciable additional losses. Itís the readerís choice if this would be believable or not.

Full Bag (Kirby 75%) Body RESULTS:
#1 with probably a few CFM less than this is the Kirby at <141 CFM
#2 with 99 CFM is the Hoover Tempo
#3 with 87 CFM is the Electrolux

Full Bag (Kirby 75%) Hose RESULTS:
#1 with probably a few CFM less than this is the Kirby at <105 CFM
#2 with 91 CFM is the Hoover Tempo
#3 with 79 CFM is the Electrolux


Post# 370476 , Reply# 4   4/11/2017 at 10:33 by wyaple (Pickerington, OH)        
And Now For The Conclusion (Text Limiting Is A Bummer)

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Percent lost from empty to full (75% Kirby) HEPA bag:
Electrolux (Body) = 14.7%, Electrolux (Hose) = 7.1%
Tempo (Body) = 13.2%, Tempo (Hose) = 14.2%
Heritage II (Body) > 12.4%, Heritage II (Hose) = 0% <- Yes, I know thatís weird but apparently Kirbyís high speed hose mode make up the difference somehow.

Bill





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