Consultant - Screw compressor


'Spraying' the impact of compressed air in manufacturing

Your first impression always leaves a lasting impression on your customer!

In business, visual cues play a key role in creating customer delight and facilitating purchase decisions. While performance & utility of the product is important on one end, aesthetics can in fact make or break your product's future.

One such method of “selling an aesthetic experience” to customers is Spray Painting- making it the most prevalent paint application technique due to its versatility and economic viability.

Compressed air plays a vital role in spray painting and there are multiple methods involved in the spray painting process including Air-atomized applicators, Airless spray, and High-volume, low-pressure (HVLP) spraying.

Let's take a look at each of these methods:
  • Air-atomized applicators are highly flexible and can be used on almost any kind of substrate, as the equipment can be adjusted and customized to suit the needs of the operator. Air-atomized applicator consists of a traditional spray gun that combines compressed air with liquid paint to create a pressurized mist that coats the surface.
  • Airless spray propels paint particles at a lower velocity than conventional air-atomized equipment, so there is less loss of paint through overspray. In this method, rather than mixing liquid paint with compressed air, airless application equipment simply forces the liquid coating through a narrow opening to create pressure.
  • In High-volume, Low-pressure (HVLP) technique the paint is released at a lower velocity, yielding less overspray and blowback than conventional air-atomized equipment. The HVLP spray equipment utilizes spray gun atomization technology that propels large quantities of low-pressure air to the gun applicator.

While there are clear visible benefits in Airless and HVLP spraying, they require advanced skill on the part of the operator, making Air-atomized spraying technique the widely preferred one.

Design of a spray gun

Paint applied by a spray gun must be even and should not drip, hence the nozzles of spray guns are designed for handling expanding, non-turbulent volume flow with high exit speed. Spray guns can also have flat, broad or round spray nozzles to suit different applications.

Types of spray guns & the compressed air requirement

Type of spray, consistency and quantity of paint to be applied determines the operating pressure and the nozzle diameter of the spray gun which in turn determines the compressed air requirement. Typically, spray guns require compressed air in the pressure range of 2 to 6 bar with an average air consumption ranging between 10 to 20 cfm.

Factors to be considered when sizing your compressor:

A reliable compressor is key to achieving high quality paint finish consistently.

  • When it comes to sizing air compressors for painting, operating pressure and flow offered by the compressor, are the critical factors to be considered.
  • The next critical factor to consider is the compressed air quality that the painting application demands. Quality of air is defined based on accepted levels of contaminants such as water, particles and oil. The air produced by any compressor, contains the same substances as the ambient air. This means that apart from dust particles, the RH factor in the ambient air contributes to water vapor and the oil used in the compressor for lubrication purpose also gets carried along with the compressed air.

It is recommended that the humidity is reduced by drying the compressed air with a refrigerant dryer, and particulate filters are installed, to reduce the amount of dust particles present in the compressed air.

An activated carbon filter can also be used to ensure there is no oil in the compressed air system. When supplementing other filters with an activated carbon filter, one achieves a quality called "technically oil-free" compressed air.

ELGi offers a wide range of oil lubricated and oil free Reciprocating and to choose from, along with the downstream equipment to suit vast range of applications. Our extensive network of authorized channel partners across the world can help to choose the best compressor model suiting your painting applications.