Auto Body Shops Pollution Prevention Guide

#6 - Paint Equipment Cleanup

Gun Washing | Solvents | Booth Filters | Booths

Equipment and paint booth cleaning can generate a large quantity of unnecessary waste if not done properly. To minimize the amount of waste generated or VOC and HAPs emissions:

  • Use an automatic gun washing system
  • Use solvent efficiently
  • Manage used paint booth filters properly
  • Use dry cleanup techniques for cleaning paint booth

Gun Washing Systems

In auto body shops, you have two basic options for cleaning your paint application equipment: manual or mechanical.

Manual cleaning techniques are still commonly used In many small shops. Unfortunately, manually cleaning spray gun systems can be time consuming and can release an excessive amount of VOCs and HAPs into the environment. They also expose the operator to potentially dangerous solvents for an extended amount of time.

Your best option is to invest in a mechanical cleaning system. Through mechanization, technicians do not have to work around potentially hazardous solvents, creating a safer and more efficient way to effectively clean paint equipment. Mechanical cleaning systems also have lids that can help prevent the loss of solvents due to evaporation.

Remember to never dispose of waste paint and solvents down storm drains, septic systems, or dry wells. This could lead to surface or groundwater contamination.

Pollution Prevention In Action
Humes Collision Center, Inc. of Minnesota replaced their old system of washing paint guns by hand with a new paint gun washing system. The gun washing system holds about eight gallons of solvent, and every few months they have to replace five gallons of solvent. By switching to the new system, Humes has reduced their solvent use and reduced labor costs. Over $7,000 a year has been saved by reduced labor and solvent costs (Autobody Repair Shop Waste Reduction Measures, 1993).

Efficient Solvent Use

Used solvent is generated from cleaning up paint equipment. To help extend the life of your solvent:

  • If feasible, use water-based paints in order to minimize the need for cleaning with solvents.
  • Reduce the number of solvents used to one type. Choose a solvent that can be used to thin paint as well.
  • Use a mechanical cleaning system
  • Schedule your paint jobs carefully to eliminate the need for frequent color changes. If feasible, schedule your paint jobs from lighter to darker colors.
  • Use used solvent as a pre-wash for tough cleaning jobs.
  • Use a solvent distillation unit to recover used solvent for reuse, and to reduce the amount of hazardous waste generated . Still bottoms and filters must be disposed of properly, usually as a hazardous waste.

Managing Paint Booth Filters Properly

In Montana, spray booths are required to be permanent total enclosures with reverse flow, down draft, or cross-ventilation systems to trap emissions and overspray. VOC controls on spray booths can help capture hazardous air emissions before they can be released into the environment.

Paint booth filters should be replaced on a regular basis. Filters that have become clogged with dust and paint reduce the air flow, make fans work harder, and consume more energy. Once the used filters have been completely dried, they can be disposed of properly. As long as the paints captured contain no heavy metals that could make them a hazardous waste, and your local solid waste authority has approved such action, the filters can be disposed of in the trash. If the filters are determined to be hazardous, you must manage them as you would the rest of your regulated hazardous waste.

A cleanable polystyrene filter element has been developed to reduce filter waste. When dirty, the filter can be blown clean with compressed air and reused (removed paint would have to be collected and disposed of properly). Filters that can no longer be reused may be dissolved in used solvent. Before purchasing polystyrene filters, you should discuss its use with your solvent recycler if you have it recycled off-site. The styrofoam may interfere with certain used solvent recycling systems.

Cleaning Paint Booths

To reduce the amount of wastewater you have to manage appropriately, use dry cleanup techniques such as sweeping and vacuuming to clean paint booths. Dispose of the debris collected from the paint booth in your appropriately.

Remember: Never dispose of wastewater down storm drains, septic systems, or dry wells. This could lead to surface or groundwater contamination.

It is also recommended that you do not clean spray guns inside the paint booth. This not only wastes paint and solvent, but could clog the booth's air filters and make cleaning up the booth walls more rigorous.

This series of questions can help you develop ways of preventing pollution in paint equipment cleanup.

Paint Equipment Cleanup YES NO
1) Do you control the type and quantity of solvent purchased? Avoid purchasing more solvent than you can use on a regular basis. If possible, purchase one solvent for multiple uses. Purchase a less hazardous solvent (review Material Safety Data Sheet) and maximize its useful life, for example by recycling it.    
2) Do you check the MSDS for a product prior to purchasing it? It is important to check the MSDS for a product prior to purchasing in order to avoid chemicals that contain hazardous materials, chlorinated compounds, or contain VOCs or HAPs.    
3) Do you have a "first in, first out" material usage policy? Using materials that have impending expiration dates first could help you avoid having to dispose of outdated materials.    
4) In your paint booth, do you try to keep non-hazardous from hazardous paint jobs segregated? To reduce hazardous waste disposal costs, segregate your paint booth operations into hazardous spray paint usage and non-hazardous spray paint usage. Non-hazardous spray paint booth waste, once dry, can be placed in your dumpster.    
5) Do you clean your guns in the paint booth? Never clean spray guns in a paint booth. Post signs in your paint areas and booths prohibiting the spraying of any solvent through lines or spray guns into booths. For all spray gun cleaning, use only enclosed gun cleaning systems.    
6) Do you use a mechanical cleaning system? To reduce VOC and HAP emissions, create a safer work environment, and reduce solvent use, use an enclosed mechanical cleaning system.    
7) Do you use reusable paint booth filters? Replace your disposable paint booth filters with reusable ones. With proper paint selection and non-hazardous cleaning solvents, these filters can be readily cleaned and reused. Newer polystyrene filters can hold up to repeated cleaning and reuse.    
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