It’s difficult to overstate the wide range of applications that use spraying technology. Spray coating systems can be used to wash fresh fruit or to frost gourmet cookies. They can also be used to apply molten glue coatings in industrial processes or paint finishes on consumer goods. And everything in between. Many of these applications are complex and require pressure control that is reliable, precise and accurate, which is why system designers frequently choose Equilibar® back pressure regulators (BPRs) for pressure control of spray coating systems due to their rapid response time, accuracy and their ability to handle difficult fluids.
Specific challenges of spray coating systems
Spraying systems may have a single nozzle or a manifold of many nozzles firing to cover the surface of the product to be coated. To perform properly, they require consistent nozzle pressure and careful nozzle valve timing.
One key challenge in spray coating systems is handling the rapid change in flow rate during start-up and shut down. For example, if a spraying line has a dozen parallel nozzles, it might take several seconds during machine start-up for each of the positions to become active as the items being sprayed move down the conveyor line. The opposite situation occurs at machine shutdown as the conveyor slows down and the last item passes under the spray nozzle manifold. During these ramping up and down times, the amount of flow through the spraying line can vary dramatically.
Accurate pressure control at the nozzle manifold is crucial to optimize throughput and achieve a consistent coating. Too little pressure and there will not be enough flow through the nozzles, leading to a weak spray that may not properly coat the item. Too high a pressure and there will be an excess of flow through the nozzle, wasting product.
Solution: high-speed back pressure regulator near exit of nozzle manifold
For challenging spraying applications, a good solution is to install a high-speed back pressure regulator near the exit of the nozzle manifold. This approach requires the installation of a circulation line back to the pump inlet, which is sometimes complex but can offer significant advantages for applications experiencing persistent pressure fluctuations. 
The Equilibar BPR is a high precision device that responds in approximately 1 millisecond to pressure changes at its inlet, which makes it well suited for spray coating systems. The speed and precision are driven by the use of compressed air, which serves as a 1:1 pilot setpoint signal to a supple diaphragm on top of multiple parallel orifices. Our devices are available in industrial designs and sanitary designs.
To learn more about how Equilibar technology offers solutions for the demands of all types of spray coating applications, see our new Pressure Control for Spray Coating page. And as always, please contact one of our experienced engineers about your specific fluid control challenge.
