Vapor Degreasing Solvents - Overview
Vapor Degreasing Solvents must be non-flammable and azeotropic (meaning that the mixture has a constant boiling point and composition throughout the cleaning).The solvent needs to be non-flammable because you have heating elements heating the solvent to boiling. So solvents like acetone, IPA, and any flammable solvent cannot be used. And Azeotropic because the solvent is being distilled as part of the vapor degreaser operation. Solvents that break down in distillation will not provide continued cleaning capability.
Three Varieties of Vapor Degreasing Solvents
The chlorinateds have been around for decades and have a higher boiling point than the newer generation of solvents. They are effective cleaners, they are non-flammable and stay azeotropes; however, they are considered carcinogens and have heavy regulations around their shipment, use, emissions and disposal. Cholorinateds are NESHAP (National Emission Standards for Hazardous Air Pollutants) regulated. With that said, many companies still use chlorinateds like trichloroethylene (TCE), n Propyl Bromide (nPB), Methylene Chloride (MC), and Perchloroethylene (PERC).
n Propyl Bromide (nPB) has been used to replace the chlorinated solvents for quite a while. It too is non-flammable and stays an azeotrope. nPB has a lower boil point than TCE or PERC and is not NESHAP regulated. It is considered a probable carcinogen. However, it has less regulation around shipment, emission and disposal.
Reliance has several excellent nPB based solvents...
The newest vapor degreasing solvents coming to market are fluorinated based. These solvents have much lower boiling points but are considered to have better health and safety profiles while still being non-flammable and staying azeotropes. There are few restrictions around shipment, use, emission and disposal.
Reliance has several excellent next generation solvents...
Considerations for Purchasing a Vapor Degreaser
What Size Vapor Degreaser Do I need?
Sizing of the vapor degreaser is fairly straightforward as it is dictated by the weight and size of the part basket. This is usually a combination of the amount of parts that need to be cleaned (production rate), the weight and size of the parts, how complex the parts are and the type of contaminant that is being cleaned.
Production through-put - Start by considering how many parts you need to process an hour. Keep in mind that the larger the "tank" of vapor degreaser the larger the cost.
Size of parts & complexity of parts - The size will dictate the number of parts per basket or increasing the tank size for processing, and complexity might mean immersion or ultrasonics are needed.
Weight of part (therefore) basket - Heavy parts require more heat input to ensure the vapor zone does not "collapse" when the parts are immersed in the zone.
Contaminant type - Light machining oils require less processing (and possibly just vapor cleaning) versus needing immersion or ultrasonics to clean the parts.
Amount of contaminant - Same as above.
Electrical needs - Ultrasonics and heat requirements will dictate electrical needs.
Floor space - Even though the vapor degreaser unit is a pretty compact system, the refrigeration systems require air circulation.
Automation - Automated basket handling systems and hoist systems are available to provide consistent basket processing and thus consistent cleaning.
Ceiling Height - Larger systems can be tall, so ceiling height does become a consideration.
Door Frame Restrictions - Moving the degreaser from shipping dock to final location might mean doors.
Ventilation - Overhead ventilation is not recommended as it reduces the efficiency of the refrigeration systems on the vapor degreaser by pulling the solvent past the refrigeration coils. Ventilation is usually at the floor if at all.
Chiller Capacity - On larger units, the chiller for the primary refrigeration unit is usually placed outside or in a separate location. The secondary refrigeration system is usually on the platform with the vapor degreaser itself.