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Aqueous Cleaning

What Is Aqueous Cleaning?

Aqueous cleaning is a process that uses a solution of detergent in water to remove organic and inorganic contaminants from an item.  Detergents can be complex formulations containing a number of components, each having a specific function but, in simple terms, they fall into two, basic categories:

  1. Those that chemically react with organic contaminants, converting them into water-soluble products.
  2. Those that emulsify the organic contaminant with water.

Within each of these broad categories, detergents encompass a wide range of chemical types and so it is important to match their chemistries with the nature of the substrate and the contaminants to be removed.

Cleaning is normally carried out at elevated temperature to increase the rate of chemical reaction.  This is further enhanced by mechanical action, usually in the form of spraying, either in air or under immersion, ultrasonic irradiation of the liquid, or agitation of the workload within the liquid.  The type of mechanical action utilised depends on the type of detergent, the geometry of the items to be cleaned and the standard of cleanliness required.  Furthermore, depending on the type of detergent, and the standard of cleanliness required, it may be necessary to follow the wash stage by one or more rinses in water, which may be purified.  If completely dry components are required, it may also be necessary to include a hot-air drying stage.

What Is a Parts Washer?

This is a term normally applied to an aqueous cleaning machine utilising sprays or immersion.

Spray parts washers can be of three, basic types:

  1. ‘Top-Loaders’ for generally smaller parts.  The spray bars are contained within a cabinet with a lid that is raised to allow components to be introduced onto a rotating work basket.  Wash solution is applied to the items via spray bars above and below the work basket.  Multi-stage models can incorporate one or more wash and rinse stages.
  2. ‘Front-Loaders’, which are physically larger pieces of equipment than the top loaders and are used to clean larger or heavier components.   Items to be cleaned are loaded via a pneumatically operated door at the front of the machine.  Again, multi-stages can be incorporated, together with hot air drying.
  3. Conveyorised machines designed to handle high-volume cleaning of relatively small parts.  Items are carried on a continuous belt that passes through separate wash, rinse and drying stages.

Immersion parts washers generally involve a series of immersion tanks for either wash or rinse stages.  Each tank can contain a work platform which will be agitated up and down causing the liquid to flow around the parts to be cleaned, thus providing mechanical assistance to the process.