Polyurethane foam guns are used for Spray Polyurethane Foam or SPF insulation. These guns are usually referred to as spray foam guns. SPF is made of two compounds which are polyol resin and and isocynate. These two compounds react with each other and also expand when they come in contact. This creates a foam which is applied on surfaces to insulate and seal gaps. The barrier created by the foam makes the room insulated against moisture and air. The tool which mixes the two compounds while spraying the resulting foam on the surface is called a spray foam gun. There are three
Types of spray foam guns which are used by SPF insulation contractors.
The three Types of spray foam guns have been discussed here.
Mechanical Purge Spray Foam Gun
Mechanical Purge Spray Foam Gun has valving rod in its chamber which separates the two chemicals from one another. As soon as the trigger is depressed, the valving rod is retracted from the chamber, thereby enabling the two chemicals to mix as they are sprayed. The valving rod returns back into the chamber as soon as the trigger is released. The returning rod also purges out any residual chemical from the chamber. Mechanical purge is a suitable type of spray foam gun for people desiring different flow rates for various types of insulation projects. It is essential to clean the valving rod to ensure proper working of a mechanical purge foam gun. This type of foam gun needs maintenance due to the presence of many working parts. Therefore, it is more suited for experienced SPF insulation professionals having a good budget for maintenance.
Solvent Purge Spray Foam Gun
Solvent Purge Spray Foam Gun requires a solvent to prevent the two chemicals from mixing with one another. The solvent also purges out any residual chemical present in the chamber after the foam has been dispensed. This type of foam gun is suited for coating but not insulation. The solvent purging mechanism means that not much air is required to flush the chamber. The solvent mechanism of the gun also enables quick switch over from small to large spray patterns. The spraying time of this gun is also more as compared to other types of spray foam guns.
Solvent purge spray foam guns are more expensive as compared to other spray foam guns because you need to purchase a solvent as well apart from the two chemicals for foam. This type of foam guns also needs regular cleaning to prevent unequal mixing of chemicals and inconsistency in spraying function.
Air Purge Spray Foam Gun
Air Purge Spray Foam Gun has a very simple mechanism to create foam. The chambers which hold the two chemicals move when the trigger is pressed, thereby causing the two chemicals to mix and create the foam. As soon as the trigger is released, a blast of air is produced which purges out any remaining chemical from the chamber. The simple mechanism of making foam and expelling residual chemical from the chamber makes air purge a popular spray foam gun option. Air purge spray foam gun also does not require much maintenance due to its simple design and very less moving parts. This type of foam spray gun is suitable when large areas need to be covered by the same spray pattern.