Most customers do not need the extra cleaning horsepower provided by co-solvent cleaning systems. However, for special applications it is a very sophisticated option.

In general, the Vertrel^® products are either single solvents or mixtures of two or more liquids that retain the same proportions at both room temperature and at the solvent's boiling point. These blends, commonly called azeotropes can be repeatedly evaporated, condensed, and recycled without changing the blend's composition or properties.

The problem arises when you can't get the cleaning horsepower you need from a single solvents or azeotrope. For example, if the solvent you chose has a boiling point of 40°C then that solvent will never get hot enough to melt away waxy residues, which typically need temperatures of 65°C or more. Fancy chemical magic cannot change the inherent physical characteristics of the solvent.

In this case, one very good option is to switch to a  co-solvent cleaning system.

A co-solvent system delivers approximately the convenience and speed of traditional solvent cleaning, but amplifies this cleaning with a second solvent. This second solvent provides the additional muscle or horsepower that the application requires.

The two solvents are very different and distinct. The primary difference between the two solvents will be their boiling points: one will boil at a low temperature (like Vertrel^®) and the other will boil at a much higher temperature.

• The high-boiling solvent is referred to as the solvating agent and usually has most of the cleaning horsepower. These are usually aggresive but slow-drying hydrocarbon solvents.
  
  
• The low-boiling solvent is referred to as the rinsing agent and is usually one or another version of Vertrel^®. The rinsing agent washes the solvating agent off the components and provides the vapor blanket for the system. System vapor losses are mainly of the low-boiling solvent.

A co-solvent system should be used only for the most difficult soils, which often require high temperatures for removal. Co-solvent systems tend to be more expensive to buy, more complex to operate and have unique safety and operational issues. However, in the right application they can provide superior cleaning results without the throughput delays inherent in aqueous systems.

First, a high-boiling, low-volatility solvating agent is used as the primary cleaner, normally followed by a rinse in Vertrel^® XF. This is normally accomplished in a two-sump vapor degreaser.

Parts are immersed into the boil sump liquid (not just the vapors). The boil sump contains the solvating agent blended with Vertrel^® XF. Ultrasonics also can be used. After cleaning in the solvating agent for a period of time, the parts are then raised over the boil sump and drained. Optionally sprayed to remove loose contaminants and the solvating agent.

Eventually the parts are moved to be over the rinse sump. The rinse sump contains only Vertrel^® XF. Ultrasonics can be used at this time to remove any final traces of soils and the solvating agent.

The parts are then lifted into the vapor zone for the drying cycle. Typical cycle times are six to fourteen minutes, depending upon the contamination.

Vertrel^® XF is ideally suited for the co-solvent process because the typical solvating agents are miscible with Vertrel^® XF, greatly improving the overall cleaning and rinsing efficiency. Typical solvating agents are:

Dibasic Esters (DBE) Aliphatic Alcohols

Aliphatic Hydrocarbons Methyl Decanoate

Propylene Glycol N-Propyl Diisobutyl DBE

N-Methyl-2-Pyrrolidone (NMP) Isopropyl Myristate

Dipropylene Glycol Butyl Ether

Dipropylene Glycol Monomethylether

Tetrahydrofurfuryl Alcohol (THFA)

Where the solvating agent is flammable, use of a co-solvent system ameliorates the flammability hazard by providing an inert vapor blanket.

A few companies offer co-solvent chemistries and the hardware in which to use them. The two best in the industry at this time are Petroferm of Florida and Kyzen of Tennessee. For details, contact Micro Care.

Check out the handy Vertrel^® Application Guide for a graphical description of the different cleaners and their capabilities, and contact Micro Care's Vertrel^® Tech Support Hotline for additional guidance at 1-888-595-4525.

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for more information about our full line of cleaning answers.