Most people have heard of “steam cleaning” carpet. One of the biggest carpet cleaning franchises in the country even uses steam in their name. There’s only one problem with that. Nobody uses steam to clean carpet.
As people began to realize that these guys weren’t really using steam to clean carpet, this method became known as hot water extraction. Once again, it has come to light that, alas, they aren’t even using hot water.
The facts came out as Aziz Ullah, Ph.D., MBA performed a test to find out how much the water temperature drops during “hot water extraction” carpet cleaning. Below are the results, according to Mr. Ullah.
To test how much the temperature will drop during hot water extraction cleaning, I did a simple test on a hot summer (90 degrees Fahrenheit) day.
The carpet was placed near the truckmount and I used a short hose to minimize heat losses.
I used a non-contact calibrated thermometer to measure the temperature (any other type of thermometer would have given a lower and erroneous reading as it would take away heat from carpet to get a reading).
The hot water coming from the truckmount under pressure was at 230 degrees Fahrenheit.
Guess what the temperature was at the cleaning wand? You may be surprised to know that at the inside area of the cleaning wand the temperature measured 124 degrees Fahrenheit and outside the wand it was only 114 degrees Fahrenheit; such was the drop in temperature.
One can surmise that on a colder day with a longer hose, the temperature at the cleaning point would be even lower.
Before everyone gets excited and thinks the machine is at fault, consider this question:
Why does the temperature drop so dramatically at the wand?
When a gas or liquid flows from high pressure to low pressure, it expands and, on expansion, loses a tremendous amount of heat.
It loses so much that you can solidify carbon dioxide gas to a solid dry ice when you open up a pressurized cylinder at room temperature (the dry ice has a temperature of -109 degrees Fahrenheit).
This is based on what is known in science as the Joule-Thomson effect.
When hot water under pressure flows from the heat exchanger or burner and goes through the wand, it loses heat as a result.
The further the wand is from the heat source, the more it will lose heat, especially in colder weather.
In addition, the hot water coming out as an atomized fan spray from the nozzle loses heat and cools down further.
The carpet also acts like a heat sink, dropping the temperature down further.
So now we see that “steam cleaning” and “hot water extraction cleaning” are both misnomers. What are these carpet cleaners calling the process now? I’ve seen the term “warm water extraction” bandied about an awful lot lately.
Continue to Part 2 of The Atlanta Carpet Cleaning Method We DON’T recommend…
