The High Lift vs High CFM debate - Cutting Through The BS | TruckMount Forums #1 Carpet Cleaning Forums

The High Lift vs High CFM debate - Cutting Through The BS

Jim Ellis

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While I have both - high cfm and high lift with my TM's I know that some ETM guys (that have to plug into a custy's house) and porty guys don't have the luxury of having the best of both worlds. Both is always better but I've done some research and have included a chart from Ametek (they use this for central vac testing) regarding actual air watts performance at the end of 30' of hose:

Airwatts Graph.jpg
 

Jim Ellis

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An explanation of the chart:

RED LINE

This line represents a system using two identical motors together in "Air Series" to create a central vacuum system withHIGH SUCTION



BLUE LINE

This line represents a system using two identical motors together in "Air Parallel" to create a central vacuum system withHIGH CFM BUT LOWER SUCTION



GREEN LINE

This line represents one single motor (an Ametek 116765 found in Cana-Vac 399 models). It offers HIGH SUCTION



What you are seeing represented in the graph above is the importance that suction plays in maintaining performance at the end of the hose and the impact it has on END OF HOSE AIRWATTS.


As you can see, the systems which have higher suction have sufficient air velocity to maintain performance at the end of the hose whereas the two motor system (blue line) with low suction suffered a big performance drop because the system lacked air velocity due to lack of suction.
 

Jim Ellis

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When Rob held the porty shoot-out he noted that lift seemed to reign supreme when testing performance of porties - it appeared harder to lift dirt out of carpet then to simply carry it back to the waste tank. In my opinion you are better off with some balance - like the 160 cfm Cobb Carpet 8.4 Breeze with 215" of lift (Larry never calculates the cfm increase you get when combining these motors in a series so I did it for him) or even the Goliath. Machines with 130" of lift like the Jag probably don't really clean carpet too terribly well because of the low lift.

Don't get hung up the orifice diameter on the chart above either - remember the end opening of your wand is much less the 2" so this chart is probably reasonably accurate for the carpet cleaning industry.
 

CCWorks

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So, the test was done using a 0,6 inch 30' hose?

Can you find the CFM?

What's the Vacuum Pressure?

PS, Other Data is missing from your data, so do not think you have it all figured out.
 

CCWorks

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Higher CFM is best after 12 to 15 Hgs.

The more CFM you have the high Hgs you will maintain in actual carpet cleaning..
 

Jim Ellis

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So, the test was done using a 0,6 inch 30' hose?

Can you find the CFM?

What's the Vacuum Pressure?

PS, Other Data is missing from your data, so do not think you have it all figured out.
Remember, this is only an illustration of how inferior lift = major performance drop off even with higher cfm's. Your lift directly affects air velocity - if you don't have enough velocity your performance and even cfm's will drop off dramatically on longer hose runs. Lift helps maintain cfm on long hose runs - and yes, cfm helps maintain lift. My point is that cfm will not compensate for wimpy lift.
 

Jim Ellis

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Remember, this is only an illustration of how inferior lift = major performance drop off even with higher cfm's. Your lift directly affects air velocity - if you don't have enough velocity your performance and even cfm's will drop off dramatically on longer hose runs. Lift helps maintain cfm on long hose runs - and yes, cfm helps maintain lift. My point is that cfm will not compensate for wimpy lift.
.6 was the "sweet spot" and can even be correlated with a wand opening at the end of a hose run - this is a central vac chart but I believe the same principles apply with carpet extraction.
 

Jim Ellis

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It was my understanding lift kicks ass with shorter hose lengths.... what would those same numbers look like at say 50 feet? 100?
As the distance increased cfm would become more and more important - I'm sure to the point that the parallel low lift vacs would eventually beat the vacs in a series. However, if the parallel vacs had more lift then their numbers would be dramatically better at any distance. I made it a point to post this to poke at certain people who poo poo lift stating that you only need the lift of a rug doctor with a lot of cfm - which is not true.
 

Jim Ellis

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Higher CFM is best after 12 to 15 Hgs.

The more CFM you have the high Hgs you will maintain in actual carpet cleaning..
I think that 15 hgs is the sweet spot in general - past 15 (and I've played - tweaked - up to 20 hgs for shits and giggles) and cfm is really the performance factor - increasing lift much past 15 hgs starts to hit the point of diminishing returns.
 

jazonfire

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Correction the goliath has a 170 inches of lift at 250 cfms had mine tested at the interlink store

Sent from my HTC One using TMF Forums mobile app
 

CCWorks

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Look at this info, test too, but I think your mind can under stand this.

If you have a 100 gal. recovery tank, 200' ft. of 2" hose, How long will it take to remove all the air in that system to reach 15 hgs using a 1/4" x 16' wand head opening at 100FCMs? I would say at least 60 seconds before any vacuum pressure is found, No vac pressure = no air flow at the wand head = no suction at all to clean carpet.

Lets add 400 more CFMs to the same set up and see how long it takes to reach 15 Hgs.

Now with more CFM you will have more back vacuum pressure because the wand head will only allow so much air in the 2" inlet, creating a more constant suction be cause the air flow is too much for the 2" opening.

The smaller the wand head opening the better the constance vacuum pressure on any system if you have 15 hgs and 100 CFMs.
The more CFMs the bigger wand head you can use, its all about suction in time. Lift time is how long it takes to build up Suction, and the more CFMs you have the better you maintain Suction.

Bottom line is CFM is more better then suction no matter how much suction you have even if it 120" of lift.

o well at least I tried.
 
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CCWorks

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To clean best, is to match the wand head opening to the amount of CFMs your system has, not section.
It is also a lot better to have the smallest waste tank, even if you add a 15 gal. waste tank with a pump to pump into a lager waste tank.
Its all about getting the max section in the shortest time.
CFM is KING!

Now Section does come into a very import part, and this is when you have to match the suction (HGs) too how much hose length and the thickness of the hose your going to run.
 
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CCWorks

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PS. Suction only comes in to play when you have 100% closed opening, and that never happens in carpet cleaning fibers.
Flood work takes suction and CFMs.
 
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Jan Sullins

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To clean best, is to match the wand head opening to the amount of CFMs your system has, not section.
It is also a lot better to have the smallest waste tank, even if you add a 15 gal. waste tank with a pump to pump into a lager waste tank.
Its all about getting the max section in the shortest time.
CFM is KING!Now Section does come into a very import part, and this is when you have to match the suction (HGs) too how much hose length and the thickness of the hose your going to run.
I have noticed that at 100 feet there is like a snap with a Jaguar 280 cfms and at past 150 ft you loose that
but when add the Power Booster 6.6 with its additional 140 cfms even at 150 feet the snap action
which is really all about air velocity created by high cfms is much greater.
. Lift is nice and I am not completely satisfied
with my Jaguar as is . But for any two cord system I think it does the best. Adding a modest
in series booster will kick the lift up to 170" water lift and even more cfms. The vac motors I have
used are made by Electro and only require 15 amps for the both of them. Even less when under
load.
 
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CCWorks

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I think what happens on a long hose run is, your air flow is tied up in the hose, like a bottle neck in plumbing, thus reaching its max lift someplace in the hose.
With a smaller wand head, I think you can make the air flow max extend farther down the hose, more towards the wand.

When you reach max lift and or air flow someplace in the hose on a long hose run, you extend your lift time to the wand, like in reverse. :)
To compensate the air flow loss on a long hose run, use a smaller wand head opening, you will not lose as much air flow at same distance, or add a booster.

Maybe even a 1.5" hose at 10' will in cress the CFMs on a long hose run ( 150') or a 1.5" tube wand with same head size of about 12"

I'm sure you can extend the bottle neck effect 50' with a smaller opening on a wand head or with the wand tube being 1.5" from a 150' 2" hose.

Sounds good, but never tested I bet.
 
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TConway

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They work together simple test to show how. Turn your tm on and set it at max then take 50 - 100' feet of hose and stick it to the carpet go out and read your lift just say it is at 13 hg's ... now go out and lower your rpm down to half, now go back and see if you can stick hose to carpet if you can then go check hg's they will be less. You need cfm to create lift or hg's.
It really is a balance between the two. I look at it as hg is horsepower the more you make the more cfm you will pull until sealed or locked down then you get very high lift but no movement= complete vacuum seal
 

john gerding

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This is above my head not going to lie... but just an observation I have made over the years in working with various truckmounts: back when I used to run blueline machines I really remember the sound of the wand being loud (high cfm) the extraction power was surprisingly underwhelming and now that i am running a truck which has a huge #7 blower the sound at the head of the wand is relatively quiet (high lift) but the extraction power is vastly superior. this is with both setups running 2" hose and 2" wands
however the blower I am using now has much larger piping between the blower and the waste tank I believe it is 8" piping. these oversized blower/tank setups offer so much more extraction power that in this debate I think lift reigns supreme.... not that you dont need both... but lift creates the extraction power that pulls deep within the carpet cfm merely keeps the water moving through the hose.
 

Larry Cobb

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We have tested many high performance portable extractors.

Using a digital vac gauge
http://www.this company does not support TMF.com/zen/images/titanvac.jpg
at the wand enables us to try different vac combinations for best performance.

We have found that AirWatts give us the best indicator of actual performance.

Right now,
have achieved the best two cord performance with the SERIES Ametek 8.4" vac motors.

We are introducing the new Cat pump system with our Breeze 84 portable:

http://www.this company does not su...n_page=product_info&cPath=85&products_id=5103

Larry
 

john gerding

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We have tested many high performance portable extractors.

Using a digital vac gauge
http://www.this company does not support TMF.com/zen/images/titanvac.jpg
at the wand enables us to try different vac combinations for best performance.

We have found that AirWatts give us the best indicator of actual performance.

Right now,
have achieved the best two cord performance with the SERIES Ametek 8.4" vac motors.

We are introducing the new Cat pump system with our Breeze 84 portable:

http://www.this company does not su...n_page=product_info&cPath=85&products_id=5103

Larry
Hey larry Im missing part of my last order from dirtfree.... and you could throw in one of those sweet vac gauges too...lol..