All atmospheric air contains water!
When the air is compressed, the water concentration increases and without any further process this air/water mix will ultimately be deposited on the surface of the part being coated. This will reduce the coating adhesion. Water in your coatings is probably the one thing you are trying to avoid, which could cause failure or premature service life due to potential corrosion issues and oil contamination of the coating.
Why does this happen?
When air travels around your factory, sometimes through hundreds of feet of pipe, condensation builds-up in the lines from exposure to temperature variations. This can be quite significant depending on what continent you are operating in. Also, a single line of air might also be feeding several other machines. Since some tools are lubricated at the connection point, that oil can back-feed into the air line, passing this contaminant downstream. By the time the air reaches the spray system, this build-up of moisture and impurities are then fed directly into the energiser components, and ultimately transferred through to the Arc or Flame spray pistol and any containments will significantly:
- Compromise coating quality by adversely affecting the appearance, adherence, finish of the coating applied and ultimately decrease its primary function to either prevent corrosion, reduce wear characteristics, or increase the likely hood of corrosion.
- Cause corrosion to components & instruments, giving false readings, interrupting, or shutting down coating processes.
- Freeze in the various lines in cold weather, which may cause faulty operation of controls.
- Decrease consumable life and even cause harm to the pistol and energiser components.
Nitrogen could be used as an alternative to clean air, however the coating would need to be evaluated to see that it is still gives the required properties as a reduction of oxide content may well change the coating adhesion and wear characteristics.
Be in the know!
A simple method to test is position a white cloth in front of the air hose to the arc spray system and see if any droplets of oil or water have been deposited.
To achieve the best performance, it is important to have the correct air supply to your system.
By utilising a drier and/or filter system this will save you money in the long run. It will help to keep your system running damage-free and your operation safe and reliable whilst extending the life of your pistol consumables, energiser components and most importantly the quality of your coating.
This short clip demonstrates condensation build up in an air line during the summer months.
Imagine if your coating had this amount of water in it! Using a refrigerated dryer eliminates this problem.