In essence, an HVLP gun remains to be an air spray gun because it makes use of air as its major atomization power. Each HVLP and standard air spray weapons use the identical two elements of compressed air, strain and quantity however in several portions. The strain, which is generally famous by way of kilos per sq. inch or PSI and quantity, which is famous by way of cubic ft per minute, are each essential for both gun to work.
Initially HVLP weapons the place designed to make use of extraordinarily excessive volumes of CFM that had been generated by generators somewhat than compressors. These generators delivered, in some circumstances, a whole bunch of CFM however little or no strain. In an effort to stay aggressive with the turbine HVLP weapons, the producers of the normal air spray weapons quickly found out how you can convert their weapons to HVLP utilizing compressed air somewhat than turbine air. At the moment HVLP weapons are as frequent because the outdated standard weapons.
HVLP know-how proved that for those who used loads of quantity of air as a substitute of loads of strain like standard weapons did, you may not solely atomize coatings but additionally accomplish that extra effectively. The effectivity enchancment was principally associated to the truth that the atomized paint particles traveled at a slower velocity than paint particles that had been atomized with excessive air strain. We consult with this attribute as spray particle velocity. The upper the speed of the paint particle the decrease the effectivity could be.
I like to make use of the analogy of a tennis ball and a cement wall. The paint particle is consultant of the atomized paint particle and the wall represents the substrate being coated. The more durable you throw the ball in opposition to the wall, the additional the ball bounces from the wall. Throughout air spray atomization the paint particle can journey at speeds higher than 30 ft per second or FPS. When the identical coating is atomized with HVLP know-how, the FPS drops to 10 to 23 FPS. The slower the particle velocity, the much less bounce again and over spray, the extra environment friendly the know-how can be.
Along with spray particle velocity, one other attribute that impacts weapons 7mm-08 ammo that use loads of quantity of air equivalent to HVLP is air damming. Right here I like to make use of the analogy of a 2′ excessive by 2′ broad by 2′ deep field and blocks which are 1′ excessive by 1′ broad by 1′ deep. On this state of affairs the field is the within of a cupboard and the blocks characterize a cubic foot of air out of your gun. Attempt to think about these blocks of air as they exit the spray gun and enter the field. If you spray into the field you might be filling it with the blocks of air. The within space of the field can solely maintain 8 cubic ft or 8 blocks, however the gun you might be utilizing is placing out 20 cubic ft per minute or 20t blocks per minute.
The result’s that inside seconds you might be placing too many blocks into the field and people additional blocks are stopping you from placing in additional blocks and they’re spilling out in all places. The quantity of air has to go someplace as a result of it often cannot go by the merchandise you are attempting to spray. The excessive quantity of air from the gun is stopping extra air and most significantly, the coating from entering into the field. That is an instance of air damming and the upper the amount of air the extra damming you’re going to get.
Along with air damming there may be the issue of air turbulence. Turbulence outcomes from sudden adjustments in wind path and velocity. This causes the plane to bounce and transfer quickly in instructions that aren’t supposed. Anybody that has ever flown in an airplane or jet has most likely skilled it first hand. Because the atomizing air exits the spray gun it begins to work together with the coating and the encompassing air within the environment creating turbulence. Moreover, the air and coating work together with the substrates’ geometry creating eddies and currents which add to the turbulence. All weapons create their very own turbulence throughout atomization however weapons with excessive atomizing pressures or excessive volumes of air will create extra turbulence than weapons that use low pressures and really low volumes of air.
So other than these traits which are shared by standard air spray, HVLP, LVLP and RP weapons, one also needs to perceive the advantages and limitations of HVLP. For essentially the most half the profit is diminished coating utilization as HVLP has been confirmed to extend ones’ switch effectivity. In essence switch effectivity is than % of paint solids that go away the spray gun throughout atomization that truly find yourself on the substrate and never within the spray sales space filters, sales space partitions or the cubicles flooring. Some producers have seen coating financial savings per sq. foot of as much as 50% whereas others might solely see financial savings of 15 to twenty%. A lot is determined by your coating, your setting, your finishers and the way effectively your standard gun was arrange within the first place.
As for the constraints, HVLP weapons use considerably extra CFM than standard weapons. Which means that you’ll probably be paying extra for electrical energy to run your compressor at finest otherwise you would possibly have to improve to a bigger compressor at worst. Though the general atomization of HVLP has significantly improved, atomization high quality might be negatively affected by excessive viscosity and or excessive move charges. Most states require that HVLP weapons be restricted to 10 psi on the air cap as a result of pressures increased than that start to lower the weapons’ effectivity considerably. So in case your materials is viscous or if you’re working excessive move charges you could be hampered by this 10-psi restrict or by the declining effectivity must you exceed 10 psi.
Low Quantity Low Strain
To assist customers with restricted compressed air availability, some gun producers have launched Low Quantity Low Strain weapons. These weapons are designed to scale back spray particle velocity like HVLP weapons, however can truly use much less air than a traditional gun. This may help cut back the excessive electrical energy prices related to the excessive cfm demand of HVLP weapons. Nonetheless, it’s endorsed that you simply consider these weapons completely for end high quality and effectivity earlier than routinely switching to this know-how. The cash you save in electrical energy could also be outweighed by a loss in effectivity or end high quality. Then once more, you could discover that a few of they’re truly extra environment friendly or offer you a greater end and prevent cash in your electrical invoice. The one means to make certain is to attempt them at your facility, along with your coatings and your finishers.