High Flow wands without Glides!

    High CFM wands #2- the Saturation Barrier
Posted By Ken Harris on 7/4/2002 at 12:15 AM
Today I would like to discuss why most carpets take over 6 hours to dry after HWE. Most water that is injected into a carpet comes back(85-95%)if you have a strong TM vacuum system.That leaves 5-15% still there,and that adds up to 2.5 to 7.5 gallons of water left in a typical 700 sq ft job.The less you leave in the carpet the faster the dry time.This post will tell you how to cut that residual moisture in half!

The reason that most cleaners leave about 5 gallons of water in the carpet are many, but the main reason is the poor extraction qualities of their wand.Most wands are designed to be cheap to build for the manufacturer and built to look good to the cleaner , but are not designed for the maximum cleaning performance.The width of the wand slot is usually set at 3/8" so the air entering will have enough velocity to catch the water /soil mix up and transport it out of the carpet.

The problem is the WCI on those wands only allow about 100 cfm .Many wands were developed in the days before TMs were around much.In those days ,2 lamb vacs in series would only produce 100 cfm or less ,so wand design was not a big concern.The manufacturers of TMs would just strengthen the wand to take the higher HG pressure ,but leave the design alone.The blowers used in the industry got more powerful until there was a huge gap in what the blower would produce and what could go through the WCI .Today the average machine puts out over 300 cfm, but only a 1/3 of that vacuum is useable, with the balance going out the releif valve!

Now that you know why todays machines do not dry carpet much better than the ones I used 20 years ago, what can you do about it? The amount of airflow that your wand can draw through the carpet fibers is the main stumbling block.100 cfm is not enough to recover the most water because that is only 1.66 cfs.Now if you were able to move 3.32 cfs(200CFM) then the wand would extract much more water.

After a carpet is wanded it starts the evaporation process. The carpet cools down 10 to 20 degrees below the room temp due to evaporative cooling.The cooler the air gets just above this carpet the slower it evaporates and the more humid it becomes.This slows the carpet drying down dramatically.

Now, if you could reduce the water left in the carpet below 2.5 gal per 700 sq ft,an interesting thing happens: the saturation barrier that forms over the damp carpet is much thinner and does not slow the drying process hardly at all.The water left in the carpet is only 1/2 what it was at the 5 gallon level but the carpet dries 3X quicker because the barrier does not contain enough water vapour to go to 90%RH anymore like it does with the higher water content.

Moving the CFM flow at the WCI up to 200 cfm or more is the best way to reduce the carpets water content AND cut the soil residue in half.Soil is suspended in the water,so if you leave only half the water, you leave only half the soil from that source too. Aeration of the wands rear lip is the easiest way to increase the air flow going into the wand. We like the PMF wand best to do this modification on because the plastic guide is thicker and easier to work on than cutting stell on most wands.This is a modification you can do yourself if you have a good understanding of air flow porting.If not , you can have this done for under $100 by someone who knows how.

Now that your wand breaths better and your dry times are under 2 hours, you are ready to capitalize on this by making it clean better too, but that is another story for later.

Good luck with the performance to be gained here first.


Ken Harris

Superglide Ken wrote:  Aeration of the wands rear lip is the easiest way to increase the air flow going into the wand. We like the PMF wand best to do this modification on because the plastic guide is thicker and easier to work on than cutting stell on most wands.This is a modification you can do yourself. Ken Harris