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Setup on an AAA sprayer is a little different than an air atomized gun. The AAA atomizes mostly by hydraulic pressure. It uses a little compressed air to atomize the tail ends of the fan. Since there is not a lot of compressed air behind the finish as it leaves the gun it travels at a lower velocity than with an air atomized gun - this results in more  finish sticking to the target and less bouncing off as overspray.

 The tips are rated by fan size and flow per minute. Many guns have a fan adjustment control on them, however, when adjusting the fan some become more circular shaped as they get smaller. You will find that you will have different tips with one flow rate to accommodate your various finishes and viscosities. You might want to get each of the different flow rated tips in both a wide and narrow fan pattern. Check with your pump manufacturer for recommendations.

 Pumps are rated as a ratio of input air to fluid compression. A 10:1 pump will put out 10 pounds of hydraulic pressure for every 1 pound of air put into the pump. A 14:1 pump will put out 14 pounds of hydraulic pressure for every 1 pound of air put into the pump and so on. When setting up the pump, you will want to use the lowest atomizing pressure that will properly atomize your finish. Too much atomizing pressure will  increase the velocity of the finish as it leaves the gun and will decrease the transfer efficiency as the finish is more prone to bounce off of the target. High pump pressures can sometimes cause bubbles to form in lower viscosity materials. Most AAA pumps atomize well at about 400 PSI. That is 40 PSI air pressure on a 10:1 pump, and about 30 PSI on a 14:1 pump. If you find that you have to raise the pump pressure significantly above these pressures you should consider going to the next size larger tip and reducing the pump pressure.

 WORDS OF CAUTION: Read your Owners  Manual and follow all precautions. A pump that is putting out 400+ PSI at the tip will have little problem blowing finish through your skin and into you. This is bound to ruin your day and you should seek medical attention immediately. AAA guns have trigger locks. Lock the trigger at all times except when you are actually spraying. Many pumps have an on/off valve right where you connect to your air supply. Turn the valve off or disconnect the air source whenever you are servicing or not actively using the pump. Even with the air supply disconnected and the regulator off, the material hose is charged with pressure. This is like having a bullet in the chamber after you remove the clip. Aim the gun into an appropriate container and pull the trigger to     discharge the line pressure. Because of the     potential for built up static electricity, always ground the pump and use the static dissipating air hose between the gun and the pump.

 To begin the setup, have your material ready with the viscosity checked and any necessary reducer or retarder added. Most pumps require very little reduction. You will find that you add solvent to compensate for temperature and aid in flow-out. You do not have to “thin” to aid atomization. Place the pumps material pick-up tube into the liquid and prime the pump. Start by having both the pump pressure and atomizing air pressure set to zero. Remove the air cap/tip. Aim the gun into a clean container or back into the material pail, release the trigger lock and pull the trigger. Slowly turn up the pump pressure until the pump cycles very slowly, 2-5 PSI of air is usually all that is necessary. Soon the material will flow out of the gun. If the pump is cycling and no material flows, check for a clog in the feed tube.

There is also a check valve ball in the bottom of the pressure cylinder where the feed tube connects. If it is not completely clean it may stick in the closed position. Use a small diameter wooden stick to push the ball up to free it. Re-engage the trigger lock. Replace the air cap/tip. Make sure that the surface of the nozzle, where the tip touches it, is clean and that the air cap is tightened sufficiently. If material comes out of the horns of the air cap you need to check the two preceding items.

Turn the pump pressure up until you have about 400 PSI at the tip, not at the gauge. Remember the pressure ratio of the pump. Release the trigger lock, and spray a pass across a piece of paper or cardboard. Adjust the pump pressure up or down slightly depending on how fast you are used to moving your hand across the target. Avoid going below 400 PSI or you may experience material build up on the tip. You will notice that the fan has “tails” on the end. Turn up your atomizing air pressure until the tails disappear.  Avoid using more atomizing air than necessary or you will increase overspray and decrease transfer efficiency. You are ready to spray.

If you are experiencing material build up on the tip, try increasing the pump pressure or dropping down one tip size. A small adjustment in reduction may also help.


By Ron Bryze at