Vacuum Pressure Impregnation (VPI) uses vacuum pressure to seal cavities in various materials such as in castings that need to be used in a leak-free application, smoothing surfaces for improved machinability, electrical windings of motors that require sealing from moisture, and infusing wood with resins to protect from exposure to the elements. The VPI process requires using a vacuum-tight chamber and pulling a vacuum to lower levels in order to remove both air and moisture from all the cavities that could trap gas or vapor.
Transport blowers have been used throughout the dry bulk transfer application for years, being relied on to move dry bulk product such as cement, powders, crushed limestone, sand, and other granular materials from the truck to the customer end point. Blowers are required to be rugged and durable in order to withstand its exposure to the element while mounted on a truck. M-D Pneumatics transport blowers are commonly seen mounted on tractor frame rails and are driven by transmission mounted power take-offs.