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.
Pump Drive System
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.
Output & Pressure Rating
A machine’s output rating is a measurement of how much mixed foam the machine will dispense in any given time period. Output is typically classified in pounds per minute, gallons per minute, or kilograms per minute. The machine’s pressure rating is a measurement of how much pressure the machine will generate to mix the chemicals at the spray gun. Pressure is typically classified as pounds per square inch (psi.) or bar for metric pressure measurement. Keep in mind that equipment manufactures often classify their machine’s maximum pressure rating as a static pressure. Operating pressure is often less than what is rated. It is important to make sure that your spray gun’s output and pressure ratings are matched to your machine.
Most high pressure thick film polyureas are commonly processed at 140°F-160°F. This temperature requirement is primarily to lower the viscosity of the liquid chemical components to assist in pumping and mixing. Often times the temperature of the material can affect spray pattern development and the physical properties of the finished polyurea product, so it is very important to assure the machines heating system is in good working order, and of enough capacity to keep up with the output of the machine.
Most proportioning machines have heaters and control systems which require an electrical connection. Hydraulic machines use an electric motor to power the hydraulic drive system, which also requires electricity. Proportioning machines can typically be ordered by the manufacturer to operate anywhere in the world. Common electrical voltages are single-phase 220v, three-phase 220v and 380v. Know where your machine will be used and be sure it is compatible with the available electrical system.