In HVLP guns, the atomization quality, that decreases with decreasing pressure, was increased with high air volume. However, HVLP spray applications require the use of more powerful compressors due to high volume air consumption, which makes the application difficult for users who are experienced applying the paint with a conventional gun. Expectations for the reduction of the air volume and increase in transfer efficiency are the main driving forces for the development of LVLP guns. In LVLP guns, the outlet pressure of the air from the orifice of the gun is kept higher than the HVLP guns, and this enables the reduction of the required air. LVLP guns seem to have the same or even slightly less air consumption than a conventional gun. Additionally, in LVLP guns, small amount of paint and air is mixed in the gun to reduce the required air volume. However, this solution is not a very applicable method for spray gun manufacturers.

As mentioned before, some states of the USA make use of HVLP guns with an air cap pressure of 0.7 bar obligatory, while other states and Europe require the use of low pressure guns with a transfer efficiency higher than 65%. However, there is no restriction on the air cap pressure. Spray gun manufacturers have focused on producing guns that can be used with low pressure compared to the conventional ones and can be used by slightly increasing the pressure when necessary. It is also aimed to produce the spray guns that are not included in the limitation of "0.7 bar air cap pressure requirement" introduced in the use of HVLP guns. For example, SATA has produced “LVLP” guns under the name of “RP-Reduced Pressure”. In RP guns produced by SATA, the inlet pressure is around 2-2.5 bar, and 0.7 bar or slightly higher pressure is obtained in the air cap. Achieved transfer efficiencies are close to the HVLP gun efficiencies. At the same time, the application speed is increased with the slightly higher air cap pressure than HVLP guns (Figure–11). Similarly, DeVilBiss introduced the GTI guns as "Compatible Guns". Thanks to the technology used in these models, the quality of atomization has also been increased.


When Table-4 is examined, it is seen that the transfer efficiencies of HVLP and LVLP guns are almost the same, but they both are relatively higher than conventional guns.



Although the manufacturer, gun quality, nozzle diameter and air cap can vary for each LVLP gun type, a typical LVLP gun consumes 260 - 300 L/min (9.2-10.6 cfm) of air and is 1.5 -1.9 Requires a kW (2.0-2.6 HP) compressor (Table-5). When these results are examined, it is seen that the compressor used for conventional guns will also be sufficient for LVLP guns and there will be no need to replace the compressor. Additionally, the increase in expected overall cost due to the use of excess air in HVLP guns are not observed in LVLP guns with low air volume. Due to the low volume of air used, there is no need to change the inner diameter of the air hose.


When the air caps are changed in the guns, number of holes in the cap and the diameter of the holes will also change which also changes the amount of air consumption. For example, 453L/min air is consumed with DeVilbiss-GTI spray gun having 2 bar entrance pressure and air cap No:105, the air consumption will decrease to 269 L/min when the air cap is switched to No:110. However, it would not be correct to call the gun HVLP, LVLP or conventional according to the amount of air consumed, because the pressure in the air cap changes. For this type of categorization, the air pressure in the air cap must be considered. Air pressure in the air cap is expected to be between 2.5-4 bars in conventional spray guns, 0,7 bar in HVLP and 0,7-0,8 bars in LVLP (Table-4).