Customer builds labeling machines. Typically they hold the label in place with vacuum generated by a squirrel cage blower then blow it onto the product when it comes into position. This application though is on a tractor/produce washer out in the farm field and the blowers do not function well.
They have compressed air from the air brake system available. Using a 3/8″ Line Vac model 6078 they used the suction side to hold the label. On the exhaust side of the Line Vac ,they installed a slide valve. Closing the valve causes the Line Vac to back flow. So instead of generating a vacuum it blows the label onto the product. The setup functioned flawlessly.