Actual CFM Testing w/Single & Dual Wands

Larry Cobb · Apr 15, 2015

Just finished our 1st Series of tests with a new Calibrated CFM meter.

Airflow results with 14" wands on the carpet . Each wand had 100ft. of 2" hose all the way to the TM (35HP w/#47 Blower @ 16").
14" Bentley single wand - 260 CFM
14" Pro Ti (devpro) single wand -230 CFM

Next we tested Dual Wands - 14" + 12" on the carpet:
14" Bentley +12" on 2nd hose = 200 CFM thru Bentley
So adding a 12" wand decreased The CFM to 77% of single wand.

Next we tried reducing the 35 HP TM lift to 13" hg (on some TM's). . . .
We tested Dual Wands 14" + 12" on the carpet:
14" Bentley +12" on 2nd hose = 165 CFM thru Bentley
So Combo of 2 wands @ 13" decreased The CFM by
17.5% compared to 16" hg Vacuum Level .
This demonstrates the requirement for high vac lift levels on TM's.

Lee Stockwell · Apr 15, 2015

PROGRESS!!!

You are finally using the right tool to measure CFM.

Now, the matter of several other variables. In a physics lab the expression is "all other factors held equal".

Dry carpet?, how does it work while actually cleaning?

Mikey P · Apr 15, 2015

The Bentley head is excellent in regards to air flow.

Larry Cobb · Apr 15, 2015

Cobb has always used actual CFM meters . . .

The 14" Greenhorn was just over 200 CFM when we tested it several yrs. ago.

The testing WAS done while 1 or 2 wands were actually cleaning carpet (prewet before extraction) ,

so they are realistic numbers (50 oz plush carpet).

There are some Bentleys with the same heads,

being done with titanium tubes as we speak.

Lee Stockwell · Apr 15, 2015

Yes I like the Bentley airflow, used every day.

Larry you earlier (don't make me dig it up) extrapolated CFM from lift measurements. This one is better, what we used at the St Louis Summerfest.

If you don't want the results skewed by recovered water while cleaning you can measure exhaust CFM. sigma IN = sigma OUT. Include relief valve.

There is also the "capacitor effect" of the waste tank, and its rise and fall time.

Larry Cobb · Apr 16, 2015

Lee Stockwell said:
Larry you earlier (don't make me dig it up) extrapolated CFM from lift measurements. This one is better, what we used at the St Louis Summerfest.

There is also the "capacitor effect" of the waste tank, and its rise and fall time.

We didn't see much rise time for the CFM readings (Ray took those readings).

We did use the digital lift meter, as shown in the photo .

It took 4 people to do some tests (2 operating wands and 2 reading instruments) .

It can be used for relative comparisons of CFM , when using the exact same wand.

Mike Draper · Apr 16, 2015

it would be interesting to hook that up to a zipper and see what your getting.

renegade_cowboy · Apr 16, 2015

Do those numbers stay the same if water if being sucked through it?

Lee Stockwell · Apr 16, 2015

Mr. Wonka said:
Do those numbers stay the same if water if being sucked through it?

No.

renegade_cowboy · Apr 16, 2015

Lee Stockwell said:
No.

What kind of CFM drop you thinking?

Nate The Great · Apr 16, 2015

Mike Draper said:
it would be interesting to hook that up to a zipper and see what your getting.

I second that..... I motion to get Lockhart to go to Cobb's place and test the CFM on the Zipper... Inquiring minds want to know....

Larry Cobb · Apr 16, 2015

Only problem with Zipper CFM testing is the adjustment of the rear glide about 0.018 above the rear glide.

This would allow extra CFM that I think has little to do with cleaning the carpet.

Can the Zipper clean carpet with weight evenly distributed between front and rear glide ?

dealtimeman · Apr 16, 2015

Nate The Great said:
I second that..... I motion to get Lockhart to go to Cobb's place and test the CFM on the Zipper... Inquiring minds want to know....[/QUOTE

I am canceling everything I was going to do today and go back to the shop grab my zipper and rush to Dallas to get this important testing done asap!

Lee Stockwell · Apr 16, 2015

I'm intrigued by competitor's comments about the limitations of a tool they haven't used.

Nate The Great · Apr 16, 2015

dealtimeman said:
I am canceling everything I was going to do today and go back to the shop grab my zipper and rush to Dallas to get this important testing done asap!

Collecting money and shoe shopping isn't a higher priority then figuring out how much CFM's run through the Zipper...... Get your priorities straight son.......... Lacoste big 50% off sale isn't till next weekend..... I'm sure you can still make it.....

JS41035 · Apr 16, 2015

At least someone is actually testing wands. It's a lot of work to do that. Most people that have access to all the wands and equipment necessary wouldn't bother.
It's a lot easier to edit a novel than to write one from scratch.

Desk Jockey · Apr 16, 2015

It seems a bit like getting caught up in the thick of thin things.

Many more productive tasks that will impact the growth of your company more than how many cfm your tool flows.

Shoe sales for example. :winky:

Jimmy L · Apr 17, 2015

So is there a redesign of that bentley coming or what?

Larry Cobb · Apr 18, 2015

Latest Bentleys will have original 14" cast head paired with a Titanium tube.

At $449, they are a great value . . .

http://www.cobbcarpet.com/zen/index.php?main_page=product_info&cPath=76&products_id=4555

Mikey P · Apr 18, 2015

that doesn't look like the ergo grip Bentley that was displayed at ICe

same crappy manifold set up.

Larry why don't you test popular wands like the PC Ti, PC Quad, Westpak 14" and 2" PMF 802?

Jimmy L · Apr 18, 2015

Larry why don't they just make that bentley manifold to spray at the front of the wand. Just make it a different style all together. And avoid the weird spray bar?

Mikey P · Apr 18, 2015

Jimmy, there was a new Bently displayed at ICe in January that had a whole new spray bar design.

I heard that it looked well designed but the goofy Atari grip and the over all (too) heavy weight of the wand were major issues.

Which is why I assume we have not seen it available yet.

Mikey P · Apr 18, 2015

Desk Jockey · Apr 18, 2015

Isn't that one Larry and Lockhart broke? :stir:

Mikey P · Apr 18, 2015

Larry Cobb · Apr 18, 2015

Old design Bentley @ $449 with modified jet assembly and titanium tube.

----------------------------------
or . . .
New design Bentley @ $699 with new jet assembly in a couple of weeks.

The one Lockhart broke was a rapid prototype, to show concept at ICE.

P.S. We asked Maison to bring a Ti wand, and Ray talked to Lockhart about one also.

Nate The Great · Apr 18, 2015

Larry Cobb said:
Old design Bentley @ $449 with modified jet assembly and titanium tube.

----------------------------------
or . . .
New design Bentley @ $699 with new jet assembly in a couple of weeks.

The one Lockhart broke was a rapid prototype, to show concept at ICE.

Way to go Lockhart..... Can't take you no place without costing people money..... :stir:

Lee Stockwell · Apr 18, 2015

I count 16 brass fittings...

Mikey P · Apr 18, 2015

And 18 yards of teflon tape..

FB19087 · Apr 18, 2015

and thats just on the outside of the fittings..............

Actual CFM Testing w/Single & Dual Wands

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