Last week I was working with a customer who was using our 36″ Full-Flow Air Knife to dry a flat copper strip as it exited the rinse cycle of their process. The customer chose the Full-Flow design due to it’s small profile, making it easier to fit into the tight space available to mount to their machine. The customer stated that they flow tested the knife before installation and the knife “worked great” but once mounted, the flow was reduced significantly. They were thinking of returning the unit under our Unconditional 30 Day Guarantee but I offered to help troubleshoot the unit to see if we couldn’t relieve their issue(s).
When they tested the unit external to the machine they were using 1″ hose (our recommendation for a 36″ Air Knife) running to a tee, which stepped down to 1/2″ ID hose going to both rear inlets on the back of the knife. But when they installed the knife, due to space limitations, they reduced the main supply to 3/8″ tubing and plumbed only 1 inlet using a quick disconnect. This explained some of the low output flow with the unit. Using undersized supply lines and quick disconnect cause significant pressure drops due to their small inside diameters. When this occurs, you aren’t able to flow enough volume of air (SCFM) to the knife, which results in reduced performance and uneven flow.
The second issue was how they had the unit mounted to the machine. Wanting to keep the air inlets easily accessible, they mounted the face of the knife (the surface the compressed air runs along) right up to the outside wall of the machine, leaving just a small gap for the output flow and built a protective shield around the unit. The Full-Flow Air Knife will entrain 30 parts of surrounding, ambient air for every 1 part (SCFM) of compressed air used. With the unit being unable to entrain any free air, the output flow is further diminished.
After increasing the supply line to both inlets, removing the quick disconnect and protective shield and moving the knife back to allow for the air entrainment, the customer called back to advise that the strip was now completely dry.