Hot water extraction

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The Hot Water Extraction (HWE) method, is a method used in chemistry for extraction and for steam cleaning (e.g. carpets). The pressurised hot water extraction (PHWE) process uses a combination of high water pressure for agitation, and hot water to increase reaction rate.

[edit] References

Pressurized Hot Water Extraction Coupled On-line with LC-GC: Determination of Polyaromatic Hydrocarbons in Sediment, Anal. Chem., 72 (14), 3070 -3076, 2000.

Though popularly called "Steam Cleaning", no actual steam is involved in the HWE cleaning process. When the cleaning solution comes in contact with the carpet/rug, it is anywhere between 120-180 degrees Fahrenheit, according to the heat available from the cleaning unit. For instance, in a modern truck-mounted carpet cleaning machine, water can be heated to 250 degrees (F), but after passing through hose and several manifolds, the water loses much of it's heat.

The typical cleaning method involves a preconditioning of the soiled surface with an alkalyn agent, followed by light agitation with a grooming brush and appropriate dwell time. Next, the surface is passed over several times with a cleaning tool (either manual or automatic) to thoroughly rinse out the preconditioner and lower the pH of the fibers to a neutral state. Finally, the surface is dried sufficiently to avoid any possibility of saturation. Inexperienced carpet cleaning companies sometimes overwet carpeting, which can lead to mildew and reocurring stains.