Polyurea is applied using commercially available plural-component proportioning equipment. It should be applied by trained, professional contractors.
The amine resin blend and isocyanate material components are typically supplied in 55-gallon drum sets. The materials must be shipped and stored according specific procedures. Once in use on the jobsite, they are transferred from 55-gallon drums to the machine using special pumps called transfer pumps.
Typical equipment used to apply Polyurea has two metering, or proportioning pumps (one for each component) that heat and proportion the isocyanate and polyol resin through heated hoses to the spray gun in a 1:1 ratio. The two materials are kept separate through this entire system until they come together in the gun, where they are mixed and spray applied to the substrate.
The drive system is what forces the metering pumps to go up and down, or back and forth. The metering pumps are the pumps that proportion, or ratio, the materials and move them out through the machine and hoses to the gun. Most drive systems are pneumatically, electrically, or electric-hydraulically driven. Pneumatically driven machines are typically less expensive, but because air is compressible, hydraulic drives are considered to be of higher performance. Read more >>
Most every commercial Polyurea Spray Gun uses impingement-mixing technology to mix the chemicals inside the gun. Pouring and injection applications can incorporate a variety of different mixing technologies including static and dynamic mix, however, in this section we will focus on spraying.
It is important to understand that once the two materials come together inside the gun to mix, they begin to react immediately as they mix and exit the spray gun. If the all of the reacted material is not expelled from the gun once the trigger is released, the material will set-up and harden inside the gun, rendering it non-usable. The design function within the spray gun that assures this does not happen is called purging. There are three basic purge systems offered by the various manufactures that offer different degrees of advantages and disadvantages, mechanical purge, air purge and solvent purge. Solvent purge is not that common in spraying foams as it is in coatings. Read more >>
However, the most common Polyurea applications are in the construction market with commercial roofing and perimeter wall insulation leading the pack. It is not always practical to lift the machine and all its auxiliary components onto a roof or into a residential home. For this reason, most Polyurea machines use several hundred feet of hose to deliver the raw materials to the spray gun for applying to the remote roof or wall surface. As mentioned previously, Polyurea needs to be heated to 140°F-160°F for optimum processing. Heating the material is the job of the pre-heaters located on the proportioning machine. Heated hoses are used to maintain the chemicals at the required temperature until they are mixed and applied with the spray gun.
This auxiliary equipment, in addition to the proportioning machines need electrical power to run and are typically powered by a mobile generator, unless power is available at the jobsite or building facility. The generator needs to be sized to handle the full load amperage draw of all jobsite equipment it is intended to power.
The transfer pumps that supply the material to the machines from the 55-gallon drums are typically air driven and require a supply of compressed air to run. Most every spray gun is air actuated, which requires yet more air. Pneumatic machines also require compressed air in specific volumes to drive their pump drive systems. A large capacity air compressor located on the jobsite or OEM facility typically satisfies these air requirements.
Mobile Spray Rigs
In any given Polyurea application, you will typically find much more equipment and power utilities in addition to the proportioning machine, spray gun and heated hoses. Many different power tools are used to prepare the substrates and perform set-up, operational and clean-up duties.Mobile Spray Rigs integrate all of the necessary tools and equipment needed for Polyurea application into a turnkey trailer system. Most of these trailers are tag along style, however, you will also see them integrated into a box truck style as well. The benefit with a mobile spray rig is that all equipment is always set-up and stored in one place. The power utilities are also included in the rig so you always have electrical power and air. Proportioning machines come in all shapes and sizes from several manufacturers. There are several major distinctions to consider when specifying and purchasing a machine: type of drive system, output and pressure capacity, heating capacity, and electrical system are the majors. Maximum and minimum hose lengths may be affected by the choices made in these major component areas.