Solvent (paint thinner) purchase and disposal fees constitute a major expense for automotive body shops. When considering pollution prevention options for the automotive painting industry, using an automatic gun wash unit in place of manual gun washing is one recommendation to decrease the frequency and the cost for product purchase and waste disposal. The Iowa Waste Reduction Center has developed a basic cost calculator to assist businesses in determining the cost benefit of purchasing such equipment.

There are several types of automatic gun wash units, ranging from one gun capacity to four, covered and uncovered versions, as well as units that are paired with solvent distillation units. All paint gun washers flush and clean paint guns within a closed system. Determining which type of unit is appropriate for a facility involves the size of the facility, amount of solvent used and the number of gun washings performed per day.

In developing this cost calculator, the IWRC focused on the typical needs of a small to medium sized automobile body shop. Energy costs were not considered in this cost-benefit analysis, and are probably negligible for this type of equipment. This cost calculator should be viewed as a general tool useful to determine if the purchase of an automatic gun wash unit would prove advantageous for the facility.

Use of a gun wash unit is a highly recommended pollution prevention option for three main reasons:

1. It decreases the number of man hours spent cleaning paint guns. It is estimated that the typical auto body shop conducts three gun washings a day, lasting anywhere between 5 and 20 minutes each. Typical automatic gun washers complete the cleaning cycle in 30-60 seconds.
2. It decreases health risks to employees. The scene of an employee sitting over an open bucket of solvent cleaning a spray gun with bare hands is common. It is true that many solvents are known carcinogens (cancer-causing agents). Using an automatic gun washer greatly decreases the employee's exposure to such agents.
3. It reuses dirty solvent that would normally be disposed of, resulting in decreased purchase of virgin solvent and disposal fees, saving the facility money over time. Solvent in the washer is used numerous times before disposal is required. Depending on the use of solvent in the facility, cleaning solvent consumption may be reduced by 50%. Some sources claim reduction up to 90%.

Pairing the use of an on site solvent distillation unit with an automatic gun wash unit can add increased advantages such as decreasing virgin solvent purchases and waste disposal fees even more. This is true because solvent distilled on site is easily used in gun wash units.

A list of automatic gun wash vendors can be found by searching the IWRC's vendor database (www.iwrc.org/newvendor/index.cfm). The IWRC does not endorse specific manufacturers, however the database is meant to be a resource for locating vendor information.

Sources:

US Navy Pollution Prevention Equipment Program. Final Report on Paint Gun Washer. 2001.

USEPA. Purchase an Enclosed Spray Gun Wash Unit.

USDA Forest Service. Environmental Tool Kit for the USDA Forest Service 1999.