Originally Published: October 4, 2021 | Last Updated: October 19, 2023
The first modified alcohol for industrial parts cleaning, DOWCLENE™ 1601, was developed in 1992. During this time, Freon – used for open-top vapor degreasing – was being banned due to ozone depletion. The modified alcohol vacuum degreasing process was one of many that gained traction as a viable “solvent replacement” option. Over the past 20+ years, the process has gained wide acceptance for precision cleaning applications. Whether with aerospace, medical or automotive components, this process has proven to provide a method that meets and exceeds customers’ expectations regarding their cleaning requirements as well as any long-term sustainability concerns.
One of the many benefits of the modified alcohol vacuum degreasing process is the process stability, both in the cleaning process and in the solvent itself.
The cleaning process stability comes from the wide variety of soil solubility that modified alcohol provides. Generally, this combines the solvency (kb value= 1000) and the process operating temperature of up to 110°C. This temperature reflects the degreasing system operating under a vacuum at 100 mbar.
Solvent stability over time can be affected by those very soils the cleaning process allows users to process. The most critical soil to be mindful of is chloride-based oils. These chlorides can be found in, but are not limited to, screw machines, stamping, and drawing oils. Other materials that add to the reactivity are water entering the cleaning process and reactive metals such as aluminum fines. In combination with the heat of the process, the chlorides, water accumulation, and metal fines will start the reactive process. The reaction causes acids to form, which, if not monitored and kept in check, can cause harm to any surface touched. Stabilizers are added to the solvent to keep the reactivity of the oils in check. The stabilizers neutralize the acids, ensuring long solvent life and materials compatibility of the components and the cleaning equipment.
Previously, customers reacted to this acid formation by adding an amine-based stabilizer determined by the solvent’s low limit pH value. These one-time adds of amine stabilizer had minimal effect on the acid, never fully neutralizing the acid. For users of large-volume systems, this was a constant fight to keep the acid in check. While this method was somewhat effective, I don’t think anyone would admit to the process being in control.
The scientists at SAFECHEM fully understood the need for a stabilization process that provided consistent results controlling the acid formation in chlorinated oil environments. As a result of their effort – the MAXISTAB™ S-Series 2-part stabilization package offered today – provides the process stability that customers expect. The new stabilization package that utilizes MAXISTAB SD-7 and MAXISTAB SV-9 is unique because it provides process-safe protection of the entire system. The stabilizers used can encapsulate the acids wherever they are found in the system. The acids are “carried” via the encapsulation to the distillation unit. They are neutralized and then discarded with the next oil discharge as part of the maintenance required for optimum performance.
Proper solvent stabilizer balance is tested regularly using the MAXICHECK DCL-1S test kit. The test data is collected to provide both raw data and visual charting, enabling users to better understand how the system functions.