CLEANING OF EQUIPMENT FOR OXYGEN SERVICE - AIGA

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AIGA 012/04
Operators carrying out emulsion cleaning shall wear facemask with appropriate filter or goggles
depending on the composition of the emulsion and on the operation conditions.
Skin contact with emulsion chemicals should be avoided as serious skin disorder can result.
See also Safety Precautions for Solvent Cleaning (paragraph 2.2.3.5) and Safety Precautions for
Detergent Cleaning (paragraph 2.2.4.2).
4.2.7 Rinsing
The purpose of rinsing is to remove remaining cleaning agents and emulsified contaminants.
This operation is performed after acid, alkaline, detergent and emulsion cleaning.
After the cleaning stage, the parts are immediately transferred to rinsing, which must be done before
the parts have dried.
The rinsing operation can take place in one or several stages by immersion, spraying or a
combination of these methods.
In immersion baths, some type of agitation is necessary. This might be accomplished by using an
impeller, water jets, air injection or movement of the parts. Ultrasonic energy can also be used to
improve the rinsing efficiency.
Spray rinsing can be used for details with smooth surfaces without cavities where all parts can be hit
by the rinsing liquid.
High rinsing temperature improves the rinsing efficiency. Hot rinsing water will also heat up the
cleaned parts, which saves time in the subsequent drying stage.
Cleaning agents with high alkalinity are more difficult to rinse away than other cleaners. Raised
temperature may then be required.
The final rinsing must be done with clean water.
The removal of liquid from the details after rinsing can be enhanced by blowing off with nitrogen or
oil-free pressurised air.
It is extremely important to perform the rinsing operation very carefully to ensure that all cleaning
products, cleaner residue as well as contaminants, are completely removed. The supplier of the
cleaner should be consulted when the rinsing conditions are decided.
4.2.8 Drying
Drying is applied to prevent corrosion and to speed up the total cleaning process in processes where
water rinsing is used. This drying operation is often the most time consuming stage in the overall
cleaning process. It may be performed in separate drying equipment or as an integrated stage in an
automated cleaning apparatus.
Drying is accomplished either with hot gas (convection) or radiation.
In hot gas drying, the necessary energy for water vaporisation is transported to the goods by the hot
gas itself.
In drying by radiation, the walls of the drying chamber are heated up, emitting heat radiation, which in
turn heats up the goods enough for water vaporisation.
The gas temperature is often in the range of 70150°C for hot gas drying. In drying, using radiation, the
parts are heated to a temperature of 150-200°C. This temperature has to be considered when drying
polymeric materials.