Choosing the Right Spray System

Electric & Pneumatic Airless Spray Pumps

Advantages:

  • Less Paint Waste – Conventional air spray uses air to atomise the paint towards a surface. This disperses many particles of paint into the air, creating overspray.   Airless spray pumps hydraulically atomize the paint without the use of air which not only minimizes over spray but reduces solvent usage.
  • Fast Application – with more paint reaching the substrate than conventional air atomised spray systems, steelwork can be coated much quicker and at a greater thickness. Up to 250 metres2/hour.
  • No thinner required – due to the high pressure pumps, heavy duty viscous paints can be applied without the need of thinners making it safer spraying with less odour.
  • One pass Coverage – with spraying at high pressure and minimum wastage it is very easy to spray the substrate in one pass to cover it.

 

Disadvantages:

  • Quality of finish – with an airless pump the paint finish is not the same as air spray and it is difficult to get a high gloss finish
  • Poor Control – with airless spray you can only reduce the pressure and change the tip to alter the spray fan. With air spray you can adjust the fan width and amount of paint on the gun
  • No good for spraying small quantities of paint (i.e. less than 5 Litres)

 

Air Assisted Airless Spray Pumps

This is a combination of airless and air spray where atomisation is created by using 50-70% of the normal airless pressure required to create paint atomisation.  With this lower amount of airless pressure the spray pattern would have tram lines bottom and top. This is known as tailing in the industry. By introducing a small amount of air (25-30psi) to the paint alongside the spray tip the tramlines are eliminated and a fully atomised spray pattern is achieved.

Advantages:

  • More control than airless, with fan pattern and paint adjustments on the gun, but with similar speed of application
  • Better transfer efficiency through spray nozzles than airless and conventional airspray
  • Better quality finish to product than airless, more like airspray finish. Ideal for higher gloss fine finishing

Disadvantages:

  • None

 

Electrostatic

Electrostatic spray guns work with Air Assisted spray pumps and Pressure Pot tanks.

The paint to be applied is charged with a negative charge up to 90KVA. When the paint is sprayed from the gun it goes for the closest earth which is the substrate which is earthed. The charge in the paint causes a large percentage of the paint to be attracted to the edges and rear of the workpiece causing a wrapping effect

Advantages:

  • Greatly reduced overspray
  • Paint saving which reduces VOC limits
  • Low booth maintenance
  • Labour saving
  • Less spraying ability required

Disadvantages:

  • Substrate must be earthed properly
  • Paint must be suitable for electrostatic use
  • Spray guns are costly to replace and must be handled with care

 

 

 

Conventional Air spray

  • Suction Feed – material is drawn from fluid container by creating venturi across top of syphon tube fitted in cup.
  • Gravity Feed – material is gravity fed from cup positioned above the spray gun.
  • Pressure Feed – material is fed to spray guns via pressure pot or remote cup under pressure. Pressure is applied by air within the pot to force material up the hoses to spray nozzle.

Paint is atomised by high pressure, high volume air bombarding paint coming out of fluid tip, which breaks it up into cloudy spray pattern. A solid coat of material is achieved by overcoating several times in various directions.

Advantages:

  • Very good finish achieved – ideal for high gloss finishing
  • Good control ability – adjustments to fan pattern and paint can be made on the gun
  • You can use very small amounts of paint

Disadvantages:

  • Poor transfer efficiency: 60% waste, i.e. overspray
  • Slow application rate
  • Can only spray low viscosity paints
  • Usually have to add thinners to apply

 

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