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32 MARCH 2014 COATINGSPROMAG.COM Safety Watch The high pressure that's used to move this sometimes very thick material through the line to the gun is what creates the hazard of using this equipment. The release of this pressure has the potential to cause great injury to the applicator or to people nearby. A irless spray of liquid coatings has become the mainstay of most contractors. Especia l ly for coatings that use litt le or no solvents, such as epox ies, conventiona l spray equipment isn't an option. A nd a lthough the advantages of rapid application rates nearly mandate the use of airless sprayers, they do come at a pr ice. In some cases, that pr ice isn't monetar y; it might cost a f inger or t wo…maybe more. One of the worse injur ies f rom airless injection that we have seen was a foreman who picked up an airless hose to see if it had a lea k in it. It d id. A nd he lost one and one-ha lf f ingers to prove it! As with any technology, we need to understand how it all works in order to determine the hazards associated with airless spray equipment. Injection-Related Injuries Airless spray derives its name from conventional spray equipment. In conventional spray, we use air to pressurize the pot that has the paint in it. Te pressure then forces the paint up the line to the gun. W hile it is true that air is also used to break up the paint stream into the spray we see, it is the use of the air to power the paint along the line that is key in this terminology. In airless spray, no air is used. Instead, the pressure used to move the paint is a pump. Te pump creates a compression and pressure of the paint alone to power it up the line to the gun. It can achieve pressures up to 6,500 psi (45 MPa) and higher. Tis pressure is far greater than the approximately 50 psi (345 kPa) or so that we used in the conventional system. Te same system is used in plural component spray systems as well. In plural component systems, two or more component paints are run up separate lines toward a spray gun where each line has a separate pump. Again, in these plural component systems, pure pressure is used to push the paint up the line and out of the gun. A lso, most of these systems use two pumps: one for the base and the other for the activator. Teir use is usually reserved for coatings with extremely short pot lives of say a few minutes to mere seconds before the coating is cured and no longer workable. Tey mix just prior to or in the spray gun, some even in the air after leaving the spray gun. The high pressure that's used to move this sometimes ver y thick material through the line to the gun is what creates the hazard of using this equipment. The release of this pressure has the potential to cause great injur y to the applicator or to people nearby. In fact, after many years in the industr y, we have seen By CP staf writers Working With Airless Spray Guns CPRO 0314.indd 32 2/18/14 5:45 PM