Cleaning Up Your Act
Choose environmentally safe cleaning materials and check the MSDS
By Fred Workley
For the last five weeks I have spoken at an Aviation Maintenance Safety Symposium five times. I keep hearing about MEK to be used in the installation of deicer boots. The way this chemical is used is by applying it with a saturated wipe. I looked up the MSDS sheet (Material Safety Data Sheet) and found out that MEK is not user friendly. MEK has both volatile organic compounds (VOC) and hazardous air pollutants (HAP) emissions.
The following traditional cleaning solvents have been used in aircraft maintenance: acetone, methyl ethyl ketone (MEK), methylene chloride, trichloroethane (TCA), and for certain uses, acetone in a mixture of toluene or xylene which are HAPs. These cleaning solvents are regulated as air-pollutants including VOCs, HAPs, and ozone-depleting substances (ODS). According to “the derived from rule” if any part of a substance includes a hazardous chemical then the whole substance is considered hazardous. See the table from a book called Emission Control Strategies, Chapter 7 titled Cleaning Operations.
Environmentally safe alternatives
For you to practice best management practices you need to find alternatives to these chemicals. However, some maintenance manuals call for their use. If you want or need to show environmental awareness and regulatory compliance you may have little choice but to find environmentally acceptable alternative cleaners. You may have to stop using solvents with large quantities of VOCs and HAPs.
Environmentally safe cleaners are either low emission solvent-based cleaners or water-based cleaners. These low emission based cleaners and solvents often reduce the regulated emissions by having low emission combinations of organic chemicals in varying blends. Two examples of friendly cleaners are terpene (from pine trees) or citrus based organic chemicals. Be careful because terpene cleaner can swell rubber but is good for cleaning carbon off of parts. These solvents are designed to reduce the VOC and HAP. Some cleaners have low volatility with also low amounts of HAP.
Low VOC and low volatility
There is a difference between low VOC and low volatility. Low VOC may only contain a very small proportion of regulated chemicals classified as VOCs. The hazardous chemical may be as low as 1 to 3 percent, but the low percentage of VOC may evaporate into the air quickly. On the other hand low volatility refers to chemicals that evaporate very slowly. Often a low volatility chemical may contain all organic compounds chosen because of their low vapor pressures. They may contain some low VOC substances that also evaporate slowly.
The best environmentally friendly cleaner minimizes emissions and is low volatility with no VOCs or HAPs. It is even better if the cleaner has no ODS. The ODS are slowly being eliminated to protect the ozone layer around the earth. In some applications the cleaner may contain very small amounts of VOCs and HAPs to get tough jobs cleaned.
Notice that acetone has no VOC, HAP, or ODS. It is not on the hazardous material list. It works great, but it has many other drawbacks. Acetone is on the way out for cleaning because it is very volatile. When you look at the MSDS (Material Safety Data Sheets) for health and safety data, acetone has high toxicity and it is very flammable. It is a skin irritant, it is absorbed by the body, and it generates a hazardous waste by-product that is not very healthy. Don’t use acetone if you can find any alternative that works for your cleaning application.
Another alternative is water-based cleaners. These are generally considered environmentally safe but may take longer and require a second application of cleaner.
There are some cleaning machines that use these water-based cleaners but not with hot water. Another way to increase their effectiveness is with a pressure spray or agitation/ultrasonic washer. Dirt and grease are carried away in emulation after some hard effort with a hard bristle brush. These water-based cleaners are not toxic and have no fumes that are flammable.
Often the water-based cleaners have a high concentration of detergents that can leave a residue on newly cleaned parts and tools. They are generally not a skin irritant but nevertheless they may not be put down a sanitary sewer drain to a water separation plant because of the detergents and contamination from the dirt, oil, Skydrol, or glycol. Thus you might have disposal problems under the Clean Water Act for contaminated groundwater. This might require you to put in an oil skimmer or a water treatment facility to treat the water before you put it into the sewer system.
Finding the best solution
So what is the best way to find a safe cleaning solution? Punt! No, it’s up to you. You know your operation and what you have to clean. You must consider safety, environmental considerations, performance, and cost. I suggest that you ask your suppliers for samples and run your own tests. Insist that the suppliers provide low emission with MSDS that you can compare. Make it very clear that these cleaners may be used on aircraft. If there is any possibility of hydrogen imbrittlement, don’t use them on stressed steel or chromed parts. Be aware that these water-based cleaners and low emission cleaner solvents don’t work as fast and may require some elbow effort. Find out what the regulatory compliance means for your operation. Practice regulatory avoidance by never being in violation of any regulation or standard. Practice best management practices. Have MSDS sheets in your work area. Train everyone on how to use MSDS for the chemicals that they use.
The use of VOC-free and HAP-free cleaners is desirable but you may have to use cleaners with a small amount of VOCs and HAPs to get good results. If so, you must keep track of how much VOCs and HAPs are used to ensure that you do not exceed the amount permitted into the air by a facility like yours. You may be required to comply with environmental regulations and permit limits to ensure air quality. Low emission cleaners may still produce solid waste like sludge that requires disposal.
Often to get the same job done, low emission cleaners are more expensive per volume than the old cleaners. On the other hand, they don’t evaporate as quickly. Low emission solvents and water-based cleaners are about two-thirds less than VOC solvents by volume. In other words, you are using less of a more expensive cleaner.
The proof of compliance is your responsibility. You do this through best management practices and record keeping. You must demonstrate that you are in compliance through your required reports. If there is a request for information you have to supply your performance track record. This is best done in this computer age by a database. An excellent source for information on compliance is found in Emission Control Strategies published by:
4891 Independence St., Ste. 270
Wheat Ridge, CO 80033
fax (303) 467-1777
Fred Workley is the president of Workley Aircraft and Maintenance Inc. in Alexandria, VA, Benton City, WA, and Indianapolis, IN. He holds an A&P certificate with an Inspection Authorization, ATP, FE, CFI-I, and advance and instrument ground instructor licenses.