A most common cause of airless spray gun problems and early failure are a result of incorrect cleaning and airless paint sprayer storage procedures.
When your airless paint spray job has completed the first step is to recover as much of the remaining paint that still remains in the airless spray unit. Consult your airless paint sprayer operation manual for the recommended procedure to remove any remaining paint from the airless machine and to properly flush the airless unit out.
Generally when using most airless paint spray pumps the first step is to open the prime spray valve, sometimes referred to as the bypass valve or the relief valve, which will relieve all pressure from the airless pump and hose.
Next remove the suction pipe or siphon hose from any remaining coating and with the airless pump bypass valve open and the return or bypass hose directed back into the original paint container turn the airless back on and let the machine run until paint stops flowing out of the return hose.
As soon as the coating stops coming out of the return hose turn the airless machine off again and then place the pump suction and return assembly into an empty container and add the coating manufacturers recommended cleaning solvent to a level that just covers the suction intake.
Start the airless spray machine with the bypass valve in the prime position and if necessary continue to add the paint manufacturers recommended cleaning solvent to enable a continuous flow back from the bypass outlet without exposing the airless pump inlet to suck air.
Wash down the outside of the suction pipe and return hose at this point using a clean paintbrush or similar device and the actual solvent that is being recycled.
Allow the airless spray machine to continue cycling solvent in this manner while removing spray tip from the airless spray gun.
Turn the airless spray machine pressure control down to absolute minimum, point and hold the outlet of the airless spray gun with the spray tip removed against the side of a grounded paint container and while holding the trigger in the on/open position turn the prime spray valve to the spray position and if no flow from the airless spray gun commences carefully increase the pressure control valve only to the point where paint gently streams from the airless spray gun back into the container. Continue this process carefully watching the stream exiting the airless spray gun and it is usually very easy to tell when solvent pushing the coating out of the hose and spray gun has reached the airless spray gun.
Remain ready to reduce the pressure instantly during the above step as the transition from viscous paint to thin solvent can be violent resulting in severe splash back if you are not careful and prepared.
As soon as solvent appears at the airless spray gun turn the pressure control back down, release the trigger on the gun then move the gun to another empty container and continue as in prevoius steps until clear solvent without paint dilution appears at the airless spray gun.
Remember to keep topping up the container that your airless spray machine is sucking from with the paint manufacturers recommended solvent through all the steps above otherwise the airless pump will suck air and may require priming again to continue.
Replace the airless spray tip that was removed in the earlier step, ensure your airless machine is primed, switch to spray mode and then increase the pressure and spray clean solvent to clear and clean the airless spray tip. When the flow is clear indicating that no residual paint remains in the airless spray unit move to the next stage.
Relieve all pressure from the a sprayer by opening the bypass valve and then turning the machine off. Remove any filters such as from the spray gun and any high-pressure manifold filters and wash these separately in clean solvent.
Reinstall the filters then prepare your airless paint spray unit for storage.