Vapor Degreaser Equipment and Ultrasonic Vapor Degreasers

If you’ve ever been wearing glasses as you walked into an air-conditioned building on a hot summer day, you already have a good understanding of part of how the vapor degreaser process works. (For those in colder climates, walking outside while wearing glasses on a cold winter day is an even better example.)

So, how does a vapor degreaser work? The vapor degreasing process is a cleaning process that uses solvent vapors (boiled solvent) rather than water to clean parts.

A vapor degreaser has two tanks (sumps) of solvent inside. One vapor degreasing tank boils the solvent (boil sump) which creates a vapor or mist of the solvent. The second sump (ultrasonic sump) is heated but not to the boiling point and is used as the second cleaning stage. The vapor degreaser also has bands of cooling coils inside just above the level of the sumps. These coils cause the vapor to return to a liquid state and fall back into the sump. The effect is like small “clouds” of the solvent are formed between the top of the sumps and the cooling tubes.

As parts at room temperature are lowered through the cooling area into the vapor, the vapor from the boil sump condenses on the parts just like moisture in the air does on your glasses in the examples above. This condensation contains the solvent that dissolves the oils on your parts, and the beading action creates droplets which run across the surfaces of the parts and fall back into the boil sump. The parts are then moved to the ultrasonic sump which contains heated but non-boiling solvent. This allows the parts to be lowered into the sump so that any blind holes or internal features are also thoroughly exposed to the solvent.

Finally parts are raised into the cooling coil area to allow the solvent to quickly dry and and then raised through a second layer of freeboard coils near the very top of the vapor degreaser that insure complete drying and the recapture of the solvent from the parts.

As the clock runs out on the 3M™ Novec™ phaseout, many manufacturers are wondering how to switch their vapor degreasers to a 3M™ Novec™ replacement solvent such as BestSolv™ Engineered Fluids.

Here are the steps to use when converting your vapor degreaser to a new solvent.

Remove Old Solvent

Completely remove the old solvent from the vapor degreaser before adding the new solvent. Any residual old solvent left in the lines may be flushed with the new solvent. Do NOT use water to clean the vapor degreaser or flush the lines.

Add New Solvent

Review the Safety Data Sheet for the new solvent prior to first use. As always when handling solvents, use appropriate protective equipment as mentioned in the Safety Data Sheet. Since most solvents are designed to evaporate quickly, be careful not to leave the solvent container open any longer than necessary.

Identify Boiling Point of New Solvent

The boiling point on your new solvent may be different from that of the old solvent. Vapor degreaser settings are based on the boiling point of the solvent used, and should be adjusted when a new solvent is used in the degreaser.

Use the Safety Data Sheet, Technical Data Sheet, or other publicly available source to identify the boiling point of the new solvent. For BestSolv™ Engineered Fluids, you can find this information through our Technical Data Sheets page.

Adjust Vapor Degreaser Settings

Use the new solvent’s boiling point as a reference for changing the following settings on your vapor degreaser:

For example, a solvent with a boiling point of 165 °F would have a Vapor Up Control (TH-1) set point of 155 °F (165 – 10 = 155).

That’s it! Your vapor degreaser is ready to return to precision cleaning with your new solvent.

NOTE: Vapor degreaser controls differ by manufacturer. Some may not contain all of the settings described.

For further information about vapor degreaser settings, see the reference section below.

Vapor Degreaser Settings Reference

• Liquid Temperature Control (LTC): Set 7-10 °F above the boiling point of the solvent being used. A 10 °F rise in the boiling point indicates that the boiling sump has accumulated the equivalent oil solution of approximately 30% by weight, along with any other contaminants. Boil down and addition of fresh solvent is recommended.
• High Temperature Control (HTC): Set 10-15 °F above the boiling point of the solvent being used. A 10 °F rise in the boiling point indicates that the boiling sump has accumulated the equivalent oil solution of approximately 30% by weight, along with any other contaminants. Continued operation may be hazardous.
• Low Level Control (LLC): A safety to turn the heat off if the liquid level falls below a safe level.
• Refrigeration Control (RT): Regulates the temperature of the cooling coils. Typically set at 45-50 °F. It is not necessary to change this setting when changing solvents.
• Solvent Vapor Control (SVC): Turns off the heat in the event of high vapor level and must be set at 10 °F below the boiling point of the solvent being used.
• Vapor Up Control (TH-1): Turns on an indicator light when the solvent vapors are up to proper level on the cooling coils. This indicates the equipment is ready to operate. It also inhibits the spray pump(s) when the vapor line is below the normal operating level. The proper temperature setting is 10 °F below the boiling point of the solvent being used.

Desiccants are used to absorb the water found in humid conditions to reduce or eliminate condensation. It can also be added directly to liquids to absorb the water content from the fluid.  We are used to seeing the small white bags of desiccant found in packaging for everything from shoes to electronic equipment.  Most of this desiccant is silica – typically in gel form.  Other common substances used as desiccants are activated charcoal and calcium chloride.

The desiccant used in vapor degreasers is 3 Angstrom Molecular Sieve, small pellets of zeolite clay. Like all desiccants, the zeolite clay adsorbs water from the solvent, and may be reused by baking it dry. Desiccants are most often used in a vapor degreaser if the solvent contains an alcohol. This is often the case with solvents used for defluxing processes on soldered boards and leads. Water found in the separator extracts the alcohol from the solvent and in turn the water and alcohol are absorbed by the zeolite clay. If a degreaser is operated in a very humid environment, a desiccant may be needed to effectively remove the water from the solvent.