[Mike Halliday]

but this must be based on lifting the wand off the carpet between strokes, if the wand never leaves the carpet then once the air is evacuated from the hose & tanks optimum suction is reach and held until the wand is lifted.

Jim, my comparison was between series & parallel , motors mounted in series will spin twice as fast as those in Parallel.

all your  maths prove is the different percentage amount of air within the hose & tank, how do you equate this to a measurement of 'efficiency'?

[Ian Gourlay]

Who said  Carpet Cleaners were not Brain surgeons

To me the test is

How Much Water I put in Solution Tank

How Much I take out of Wate Tank

But very interesting  never thought about Size of waste tank making a diffrence to performance.

[robert meldrum]

As the saying goes " size isn't everything "....................it's what you do with it !

[Doctor Carpet (Ret'd)]

I'm an innocent abroad. I'd never even considered the issues raised by Jim, Mike and AJB.

Thanks for that guys- a lot to ponder on, Much food for thought.

I think I'll stick to spouting on financial/business matters where my expertise lies.

[Jim_77]

Mike, true to a large extent about not lifting the wand - probably different with upholstery though.

However I'm sorry but I don't think you're right about the motors spinning twice as fast if you put two in series!!  it doesn't matter how many you put in series, they'll all spin at the same speed as a single motor (in theory).  If the fans in the motors are spinning faster they'll produce more cfm's won't they?  And we all know that series doesn't increase cfm's it increases lift.

The "efficiency" I suppose was a little tongue in cheek, it's a kind of salesman talk really   I suppose it's how long it takes to create a vacuum.  In this field of application, the shorter time the better.

[Mike Halliday]

Jim,  we'll have to agree to disagree on that one ( altjough I know I'm right )

[Jim_77]

Although I know you're wrong, I'll settle with you

[Ian Gourlay]

Just been thinking

If You have a TWO INCH  HOSE is there not more air in SYSTEM and AIR to Expel

So does that not throw the smaller wate tank theory out as we are told TWO INCH is the new standard

[Jim_77]

[richy27]

its too late goin bed have headache reading about parallel in series 2 inch more suck small tanks.

[AJB]

1 1/2" hose will flow up to approx 230 CFM without affecting performance, so if you use a
machine that is above this figure ie Scorpion or other triple vac' machine, then 1 1/2" hose
restricts the performance. On a series vac' machine, using 2" hose will degrade performance
as there is more air to evacuate to reach optimum lift.

I don't know the correct figure for 2" hose but by my reckoning

a 2" hose has a cross section of 3.14159 sq",

a 1 1/2" = 1.767Sq", so is 56% of the 2".

230/56 x 100 = 410 CFM

So unless a Truckmount has more than 410 CFM using 4" pipe to the door doesn't
actually improve performance