A metal products manufacturer was using a water-based paint to provide a corrosion-proof coating on their products. The paint was previously solvent based, so the plant staff decided to install a compressed air mixer to prevent any risk of explosion. But air mixers were expensive, so the maintenance personnel simply installed a compressed air powered hand drill instead, with a paint mixer bit, something that was readily available in the plant. The drill trigger was lashed open and the drill operated on a 24 x 7 basis.
After a few years, the paint was switched to water-based, in order to meet with environmental standards. There was no need to provide explosion-proof mixing … however, the air powered drill remained in place.
The drill was installed with no lubricator on the inlet, and it wasn’t constructed to operate full time, so after a few years the internal vanes of the drill started to wear, reducing the output power, and increasing the compressed air consumption. The drill’s compressed air flow went from its rated 10 cfm up to a flow of 35 cfm, due to internal leakage. This consumption costs the company about $7,000 per year in electrical costs.
An investigation showed an electric mixer, consuming no compressed air, could be installed that would use about 500 watts and costing $500 per year. The cost of the mixer is estimated at $1,000 plus installation. Simple payback for the project is expected to be less than one year.