The PVG-1 is a compact pressure or vacuum generator that provides a constant air source ideal for field calibrating differential pressure air flow sensing switches. For quick and easy set up, it has separate coarse adjustment valves for initial pressure or vacuum range selection, a fine-tune output adjustment potentiometer, and a push button on/off switch. The output range is ±0.10 to ±12.0″ w.c. Three standard AA size batteries provide a minimum operating life of ten hours. A protective cover is included for durability in the field. PVG-1 has integral slip-on tubing connections that accept both ⅛” ID and ¼” ID flexible tubing. A tubing accessory kit for connections to both an air switch and a manometer is included with the PVG-1.