| Atomization Technologies Part 1 Conventional Air | | | | amount of atomizing air pressure that is used. |
| Spray | | | | The higher the atomizing air, the higher the fluid |
| Atomization can be defined as a method by which | | | | flow rate would be. The lack of an independent |
| force is used to convert a liquid stream into fine | | | | control of the atomizing air in relationship to the |
| spray particles. The force can be from | | | | fluid flow rate is why the siphon gun is the least |
| compressed air, from pumps that pressurize the | | | | transfer efficient of the three types of feed |
| fluid, from centrifugal forces, from electrostatic | | | | designs. The faster the application, the higher the |
| forces and by various combinations of the above. | | | | atomizing air would need to be. The higher the air |
| For our purposes, we refer to these methods as | | | | pressure, the more over spray and bounce back |
| atomization technologies. For finishing, the use of | | | | there would be. |
| atomization technologies allows us to apply | | | | With gravity fed guns, the fluid is delivered to the |
| coatings for decorative, protective or adherent | | | | gun from a cup located on the top of the gun. In |
| purposes or for a combination thereof. To help | | | | this case, the fluid flow is mostly controlled by |
| you understand the similarities and the differences | | | | gravity. The gravitational force on the coating |
| between these technologies, we offer the | | | | itself would allow the fluid to flow through the |
| following explanations. We will discuss other | | | | guns' fluid nozzle thus reducing the amount of |
| technologies in future articles. | | | | atomizing air needed for fluid flow purposes. |
| Conventional Spray Guns | | | | Obviously, the flow would be affected by the |
| Often referred to as air spray, this technology | | | | coatings viscosity, the size of the fluid nozzle and |
| uses compressed air as its primary atomization | | | | somewhat by the atomizing air. The atomizing air |
| force. As the fluid exits the spray guns' fluid | | | | can now be used more for atomizing and less for |
| nozzle, jets of air directed by the spray guns air | | | | fluid flow concerns. Another advantage to gravity |
| cap intersect the fluid stream. This causes the | | | | guns over siphon guns is that they do not spit or |
| fluid stream to break apart into the fine spray | | | | splatter when the cup runs out of fluid. They just |
| particles. This portion of the air from the air cap is | | | | stops spraying. |
| referred to as the atomizing air. Additional jets of | | | | Pressure fed guns are the best of the three basic |
| air from the air cap are used simultaneously to | | | | designs as the fluid flow is independently controlled |
| help distribute the particles into a fan like shape | | | | from the atomizing air by an additional air |
| referred to as the spray pattern. This portion of | | | | regulator or valve. Pressure fed cups are now |
| the air from the air cap is referred to as the fan | | | | widely used as a replacement for the old |
| air or the pattern air. | | | | traditional siphon gun, especially with HVLP guns. |
| The fluid may be delivered to the gun in a variety | | | | The reason for this is that HVLP siphon guns just |
| of ways. It can be attached to the gun directly | | | | do not have enough siphoning power for todays' |
| by means of a cup. The cup can be a siphon cup, | | | | higher solids coatings. They work well with thin |
| a gravity cup or a pressure cup. The least | | | | coatings such as stains however. |
| efficient yet historically most popular configuration | | | | Another advantage of pressure fed guns is that |
| was the siphon or cup gun. As its mane implies | | | | they allow the finisher to spray from any angle, |
| the gun used the compressed air from the air cap | | | | unlike siphon and gravity fed guns. If you tip |
| to create a siphoning action just in front of the | | | | gravity or a siphon gun too far while spraying you |
| spray guns' fluid nozzle. As the fluid in the cup is | | | | will interrupt the fluid flow to the gun. Remote |
| at atmospheric pressure, the fluid would move | | | | pressure cups, pressure pots and low-pressure |
| towards the vacuum created by the air cap and | | | | pumps for higher production applications can also |
| be siphoned out of the cup. The amount of fluid | | | | feed pressure fed guns. |
| that the gun could spray is directly related to the | | | | |