Page 5 of 7
The manual AK-HH HVAF equipment sprays powders, heated and accelerated by the combustion products of the air-fuel gas mixture.
- When entering the gun, the compressed air cools the gun. Then the preheated air is used for mixing with the fuel gas for combustion.
- The mixture of pre-heated compressed air and fuel gas flows into the combustion chamber through the orifices of a catalytic ceramic insert.
- The initial spark plug ignition of the mixture results in the heating of the insert above the mixture’s auto-ignition temperature than the hot insert then continuously ignites the mixture.
- The spray powder is injected axially into a wide combustion chamber, where the gas flow is very slow, less than 40 m/s (130 ft./sec.)
- The long residence time and exposure to favorable heat transfer conditions at high gas pressure, allows the powder to heat efficiently in the chamber.
- As an optional tool for a proper heating, one may inject controlled amounts of a high heat conductivity gas (hydrogen, helium).
- The powder leaving the chamber is propelled into the nozzle of chosen length and configuration, where it is accelerated to a velocity that may be from 800 m/s to over 1000 m/s (2,600-3,300+ ft./sec.), dependent on the chosen nozzle and combustion chamber pressure.
- When impacting a substrate, the spray powder particles form a surface coating.