Airless Degreasers
The term Airless Degreaser has been used to describe a variety of equipment available in the cleaning market today. There is no actual definition of an Airless system. When we coined this phrase in the 1990’s, it referred to cleaning systems that removed air from a cleaning chamber before cleaning. Completely removing air from a chamber, as is done in the semiconductor industry, is expensive and unnecessary to achieve the cleaning performance and reduce emissions to acceptable levels. Our solvent units operating in the field remove at least 95% of the air present before solvent is introduced into the chamber. Large systems remove 99% plus because of the larger emissions associated with the larger volumes.
The main goal of initially removing air was to prevent contact between air and the solvent. Once contact is made, it is very difficult and expensive to remove the solvent from the contaminated air, since the mixture is a single phase that requires treatment such as cooling or carbon adsorption. Recovery of solvent from an “airless” degreaser can be accomplished by simple condensing. After air is removed from the chamber, the system becomes completely closed, meaning no air or solvent is transferred to or from the existing equipment. The last step in an enclosed system is vacuum drying. When completed, the chamber is returned to a state near the pressure and condition, except for contaminant removal to a sump pump, that the chamber was in after the initial vacuum. At that point, air is introduced to return the chamber to atmospheric pressure, allowing it to open and the part to be removed. Because the system starts and ends with a vacuum, the EPA sometimes refers to this type of equipment as a Vacuum-to-Vacuum Degreaser.
An “Airless” system can best be described as an enclosed system that transfers solvent internally in both liquid and vapor forms to perform various cleaning processes. These processes include vapor degreasing, spray cleaning, liquid soaking, liquid jetting, ultrasonic cleaning, vacuum drying, and convective drying, all performed without an air-liquid interface or an air-vapor mixture in the cleaning chamber.