This can be done by wiping it down with a dry cloth and then spraying the cloth with compressed air to remove any debris on the surface. If there are stubborn stains or dirt, you may need to use some type of cleaners like soap and water or wax and grease remover.
[pdf] External air is introduced into the air compressor through forced convection by a cooling fan. When the air flows through the plate-fin radiator, it carries away the heat generated by the compressor (including lubricating oil and compressed air).
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