Thread Number: 34496  /  Tag: Recent Vacuum Cleaners from past 20 years
Bill's Inexpensive Airflow Box and Anemometer
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Post# 373005   5/31/2017 at 16:41 (356 days old) by wyaple (Pickerington, OH)        

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Hi all,

If you want to see some of my inexpensive testing equipment, I've posted a new "How To" video on my channel.


Post# 373035 , Reply# 1   5/31/2017 at 21:54 (356 days old) by Tekjunkie28 (Roanoke Va)        

Oh boy!!! What have you tested so far? Any rainbows? I'd like to see a test of the E2 black with and without hepa. I have a CFM meter but I need more testing with it and something to back it up.

My very rough findings of the CFM of a E2 is 100 CFM but I bets that's incorrect.

Post# 373038 , Reply# 2   5/31/2017 at 22:58 (356 days old) by wyaple (Pickerington, OH)        

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Not my tests, but for a Rainbow E2 2-Speed the airflow is 77 CFM from the hose end and probably will drop to 55-60 CFM by the time I would measure it at the power nozzle.

My actual tests of a D4C SE shows 42 CFM and D4C SE PE shows 33 CFM at the nozzle respectively.

Rainbows have never had great airflow unfortunately.


Post# 373044 , Reply# 3   6/1/2017 at 06:33 (355 days old) by Tekjunkie28 (Roanoke Va)        

That doesn't seem right though. When I'm using mine it feels very strong compared to other vacs I've had. Even more then my kenmore Elite with induction motor. Have you measured any vacs with empty bag bs full bag?

The instrument I have is a airflow meter designed for duct work. It has been tested in that application and was very accurate compared with the $1200 equipment that's typically used. If I had it setup correctly and whatnot the. The cfm out of the back of a E2 is about 100 cfm

Post# 373055 , Reply# 4   6/1/2017 at 09:48 (355 days old) by wyaple (Pickerington, OH)        
We are talking about a water based Rainbow, Right?

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"I'd like to see a test of the E2 black with and without hepa."
--Rainbows don't use bags, they use water. Yes, I know they have a HEPA exhaust filter, but it just sounds weird to say, "measure your Rainbow without HEPA".

"The cfm out of the back of a E2 is about 100 cfm"
--Exhaust airflow doesn't usually correlate to hose or nozzle airflow.

Here are my measurements for a 1997 D4C SE PE
Measured at the body = 3071 ft/min = 80.2 CFM
Measured at the hose = 2303 ft/min = 60.1 CFM
Measured at the exhaust base = 4311 ft/min = 113 CFM
Measured at the exhaust hose = 3779 ft/min = 98.6 CFM

As you can see the exhaust air is much more powerful than the "vacuum" air.

As an additional reference, please search my posts here on VL that have words with "Airflow Losses" in the title and you'll find things like this:

Post# 373064 , Reply# 5   6/1/2017 at 12:00 (355 days old) by sebo4me (Cardiff)        

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Very good work Bill 👍

Post# 373072 , Reply# 6   6/1/2017 at 16:36 (355 days old) by Tekjunkie28 (Roanoke Va)        

Thanks Bill!!! So your 113 CFM is close enough to what I was reading and with the new power nozzle the CFM should be higher. I'm going to play around more with this and see if I can make some way to get more consistent readings. There's more even suction and continuous suction then my previous cleaners. It might not be eureka bagged smartvac suction but it still over keeps my floors cleaner.

I wish I still had that Eureka.

Post# 373075 , Reply# 7   6/1/2017 at 18:08 (355 days old) by wyaple (Pickerington, OH)        
Just to make sure I'm understanding you...

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You mention that 113 CFM at the exhaust port correlates closely to what you measured with your equipment, right? BUT, that's the exhaust CFM, not the hose or nozzle CFM. If you were only attempting to verify exhaust CFM, then we're good. If you were equating exhaust CFM with hose/nozzle CFM, there must be some kind of disconnect here.

So just to be clear: My 1997 D4C SE PE does 60 CFM at the hose end and another YouTuber has measured an E2 2-speed and found that the hose (not exhaust) airflow is 77 CFM.


Post# 373083 , Reply# 8   6/1/2017 at 21:37 (355 days old) by wyaple (Pickerington, OH)        
My first live airflow box test has been posted

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And I choose the highest performing machine in my collection to show everyone how I calculate nozzle airflow as inexpensively as possible.


Post# 373087 , Reply# 9   6/1/2017 at 22:16 (355 days old) by Tekjunkie28 (Roanoke Va)        

Yes I was referring to your finding one CFM at the exhaust. 77 CFM at hose end sounds correct. Your found 113 CFM at the exhaust of your machine and I found 100 but depending on how I hold the instrument it gets much higher. I'll check again this weekend if I have time.

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