How much does the air cost that I use in my spray gun?

Is air free? Technically, the air we use is free, but the cost to compress that air is not. Factors to consider are:

• Local electrical costs
• Type of compressor
• Pressure used for spraying
• CFM consumed
• Amount of time the trigger is being pulled
• Number of coats being applied.
• Efficiency of the gun/cap/tip combination

Before getting into the cost calculation, let’s cover some of the not so obvious factors.

The consumer type compressors that are bought from the big box stores typically do not provide enough air volume for industrial applications. Two stage compressors provide higher pressures and volumes required.

The air pressure supplied to the spray gun should be set at the lowest pressure that will allow the atomization required and still allow the operator to accomplish the production required. Higher than required pressures result in higher air consumption; therefore higher electrical costs.

In general, it is more economical to apply the finish coat in one pass than using two thinner coats. Less paint is used and less electricity is used. Be sure to check your coatings Technical Data Sheet for proper application and film builds.

To find out the actual air consumption, check the literature supplied with the spray gun. For pressures not listed in the literature, contact your equipment manufacturer or supplier.

To calculate the daily electrical costs for the air in a spray gun use the following formula:

DC X HD X EC X CFM X .228

• DC = Duty Cycle = Percent of time trigger is being pulled
• HD = Hours in work day
• EC = Electrical cost per kilowatt hour (.0935 national commercial average July 07)
• CFM = CFM rating or air consumption of the gun
• .228 – Electrical consumption of 1 CFM in KWh

For example, what is my annual cost to supply the air for my 18 CFM air cap? How much would I save if I lowered my pressure to a pressure that consumes 12 CFM or use a different air cap that consumes 12 CFM?

My factors are:

• Duty cycle = 50%
• Work day = 15 hours
• Cost per KWh = $.10
• Days per year = 250
• 18 CFM Air Cap

.5 X 15 X .1 X 18 X .228 X 250 = $769.50 annual electrical costs

Compare the above to a gun/pressure combination consuming 12 CFM

.5 X 15 X .1 X 12 X .228 X 250 = $513.00 annual electrical costs

Lowering air consumption by using lower air pressures or using an air cap with less air consumption would result in an annual savings of $256.50 per spray gun.

The above calculations are based on typical efficiencies and are approximate. The change in cost is proportional and is correct as a percent of the higher cost.