[mark_roberts]

How can I determine the most strongest vacuum performance for drying carpets without going by the manufacturers figures?

Today I did a test.  Got 1 foam block and set it on the ground.  Set the hose cuff horizontal on the ground and measured the distance it took for the block to be sucked towards the hose.  Is this measuring cfm?

Machine 1 - 50ft of 2 inch hose.  About 4 inchs
Machine 2 - 50ft of 2inch hose. About 3 inchs
Machine 3 - 15ft of 1 1/2 inch hose.  About 4 inchs

With the hand over the cuff test its hard to determine the strongest vac.

thanks
Mark

[Dynafoam]

Mark,

The tests you conducted , though they will not 'measure' the airflow, are reasonable for comparison. The actual measuring devices are similar to speedometers, driven by an impeller.

I once constructed a device that consisted of a vertical, transparent plastic tube, open at the bottom. Inside was a golf ball, which was less than half the tubes' diameter. The vacuum hose was attached to the top, so that the height the ball rose gave a similar comparison to your method.

Putting a hand over the cuff will not indicate airflow, but vacuum lift.

[Ed Valentine]

This is an interesting topic.

My good friend, John Bolton, pretty much summed it up in his terrific answer as always.

Therefore, just to add to his answer, the "strongest vacuum" does not always mean the "Best Vacuum" as it relates to this business. (ex: putting ones hand over the end of the hose; or etc...)

Good Fortune to all;
Ed valentine
cross-american corp.

[Bob_Savage]

I agree with John, and Ed V.

It's the balance of lift and airflow, optimized for both, which will give you the BEST drying times!

Bob Savage
www.savage-1.com

[Neil Gott]

Put a measured amount of cleaning solution into the fresh tank, use it up, and then measure the amount in the waste tank.

This won't produce a hard figure, but it will give you a rough indication of efficiency. Fibre and construction need to be the same when comparing performances. Crude maybe, but the proof of the pudding is in the eating, whtever name it is given.

I find the result is often about 30% less than that claimed by the supplier.

[Dynafoam]

The procedure mentioned by Neil, is one that I conduct on single machines on an almost constant basis - keeps a check on me and the machine 

Neil mentioned the constancy of the carpets, but other factors can effect the results. More water is lost by evaporation within the system when using high-airflow machines and wanding, as it is when using higher solution temperatures, so these also should be kept constant.