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Spray painting booth; Spray paint air gun; Industrial dust collector

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Spray painting equipment refers to the collection of devices used to apply a surface coating to objects by the means of atomized liquids that are propelled through the air, usually by compressed air. It also refers to a series of devices used to optimize the coating application.

 

Spray Painting Process

A paint, stain, ink, varnish, lacquer, or polyurethane is pressurized and forced into droplets or aerosol by a high-velocity airstream that also serves to distribute the coating on a surface. The spray is patterned onto the workpiece by an applicator, and cleaning and curing equipment helps perfect the paint's adhesion.

 

The following components are utilized in commercial and industrial painting applications.

A nozzle, gun, or wand utilizes the Venturi effect to coat a surface. The tools are meant to be handheld or used in an automated paint spraying system. These dictate the pattern, droplet size, angle, and intensity of the spray. Some spray systems support multiple applicators.

Selecting paint spray applicator 

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  • Power source
A powered paint sprayer is supplied by either a gas-powered or electric motor, whose operational strength is rated in horsepower.

Selecting paint spray power source

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  • Pressure source
An air compressor or pump feeds the surface coating through the painting system. This contributes to the flow rate of the paint and pressure is represented in PSI. Turbines are also commonplace.

Selecting paint sprayer compressor

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  • Media
A variety of surface finishing liquids can be applied by a spray system, though latex or oil-based paint is most common. Other agents may require thinning to be used in spray systems.

How to select spray coatings

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The system's integrated basin for paint awaiting application. These range in size from small cups to paint drums.

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  • Handling equipment
Large, heavy-duty paint spraying systems, or systems meant to paint outdoor terrain, often require a truck or cart for transportation or operation.

Selecting paint sprayer handling equipment

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  • Application enclosures
Since between 20 to 40 percent of the spray can be lost due to overspray and droplet drift, spray booths keep wayward particles within an enclosure. These range in size from cabinets to garage-like environments to accommodate a variety of components.

Selecting spray booths

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  • Ventilation equipment
Due to the airborne concentration of minuscule paint droplets, respirators and ventilation equipment are often legally-required components in the spray painting process. Spray booths often incorporate a blower or overhead hood.

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  • Electrode
An electrode is immersed in the reservoir, attached to the applicator, or used to create an electrostatic field. This charges the paint, and the component to be sprayed is oppositely charged or grounded. The paint is attracted to the component to greatly increase coating efficiency.

Selecting electrostatic paint electrode

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  • Curing units
Convection and infrared ovens are used to expedite the drying process of certain paints and surface coatings.

Selecting paint drying oven

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  • Spinning bell/disc
A spinning bell or disc is used to atomize and electrically charge the paint particles via centrifugal forces. An airstream directs the paint towards the part, which has been charged or grounded. 

Rotary disc spraying

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  •  Part feeder
In high volume spray applications it can be beneficial to have a conveyor or part placement system to assist in moving unfinished and finished components between processes. 

Selecting part feeders

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Atomizing Technology

Generally speaking, there are four methods utilized to produce droplet-sized particles and impart direction upon the spray agent. This technology in conjunction with the applicator determines if the spray pattern and intensity.

  • Airless: Paint spraying or application system using high fluid pressure to atomize paint by forcing it through a small orifice. Paint under high pressure is passed through a nozzle and broken down into droplets, or "atomized," where it enters the lower pressure region outside the gun tip. (Less air is used than in conventional air spraying so that the problems of dry spray and paint bounce-back is reduced.)
  • Airless (air-assisted): Air-assisted airless spray process is used to alter the spray fan shape pattern, but not to atomize the paint.
  • Air atomized: Paint application system wherein paint is atomized by combination with compressed air. System of applying paint in the form of tiny droplets in air, i.e., paint is broken down into droplets, or "atomized," by a spray gun as a result of being forced into a high velocity air stream. Shape and paint density of the resulting droplet cloud can be controlled by air pressure, paint viscosity, and gun tip geometry.
  • Rotary cup/disc: Rotary spray guns or applicators use a rapidly spinning cup/bell or flat disc to project powders or atomize paint. Rotary cup or bell rotary applicators produce a fan pattern, which is closer to a nozzle spray gun. A rotating head is shaped to deliver paint forward in a circular pattern. The bell may be directed at any angle and be moved on robots or reciprocators, just as nozzle spray guns are. Disc rotary applicators spin the coating media out radially. Rotating heads that deliver paint horizontally 360° around the head are useful on omega loop conveyor finishing lines. A disk is usually mounted horizontally on a vertical reciprocator. Disc rotary spray guns are also useful for internal or ID coating applications.

In an effort to reduce energy and material consumption, many spray painting operations systems utilize high volume, low pressure (HVLP) or low volume, low pressure (LVLP) systems to spray coat items with large surface areas. These spray techniques are often driven by turbines, not compressors.

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Common Spray Painting Systems

Aerosol Can

Selecting aerosol paint can

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A can is filled with the spray media before it is filled with compressed hydrofluorocarbons. The can is crimped and tapped, and when the user depresses the nozzle the propellant/paint mixture is forced through the applicator. The paint repels away from itself once it disperses from the nozzle, resulting in a fine, even mist. Plug-in wands and guns are available for aerosol cans.

Handheld, refillable

             

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Marketed towards DIYers and low-level commercial applications, integrating a pressure source, reservoir, and applicator into a lightweight footprint that is easily managed. Battery-powered variants offer the most flexibility for unusual locations.

                          

Handtruck mounted

Selecting cart spray painters

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Spray painting systems where major components such as the motor, compressor, and reservoir are located on a wheeled cart or truck are intended for large-scale painting applications. These systems can be transported to job sites, but the operator must stay within the tethered range of painting system.  

 

Spraying bays

Selecting spray painting bays

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Spraying systems in bays and booths are permanent fixtures that can only be operated within the enclosure. The applicator would be hose-tethered to the reservoir, motor, and compressor. These systems often integrate ventilation and dust collection systems as well.

Line marking equipment

selecting line markers

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Painted lines appear on athletic fields and construction sites by the use of spray systems with ground-facing nozzles. The operator accompanies the system, applying the spray pattern to the terrain. It is used to mark boundaries and points of interest.

Vehicle mounted

Spray painting truck

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Spray painting systems may be mounted on a service truck for unique applications. Lines on roadways are applied via trucks with integral line-marking applicators.

 

Spray Painting Safety

There are inherent risks to applying paints via spray systems. Air-suspended particles and paint fumes present an inhalation risk, and skin contact should be avoided. Latex-based coatings, which are water soluble, are the easiest to clean and have minimal vapor. Ventilation systems, respirators, and coveralls are recommended where applicable, and in many jurisdictions are legally required in indoor or confined application areas.

 

- OSHA regulations on spray booth ventilation (external link)

- OSHA regulations on respirator usage (external link)

 

Spray Painting Standards

 

-A-A-50310 Heavy duty spray paint gun

-A-A-59564 Spray paint fluid containers

-BS EN 28028 Hose assemblies for airless paint sprayers

-SAA AS/NZS 4114.1 Construction, testing of spray paint booths

-ANSI Z9.3 Design of spray ventilation systems

-SAE AMS2505 Baking enamel paints for aerospace applications

-BS EN 50059 Electrostatic, handheld spray painting

 

Resources

 

Grainger - Paints Sprayers and Accessories

 

Facilities Net - A Closer Look at Paint-Spray Technology

 

Wikipedia - Spray painting; Rotational bell painting

Read user Insights about Spray Painting Equipment (Paint Sprayers)

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