GP21 Positive Pressure Ventilator equipped with Honda GX160 Series 4 cycle gasoline engine with oil sensor system and Cyclone type air filter. Positive Pressure Ventilators are specifically designed for construction and industrial-related job applications. Contractors use PPV fans to ventilate the interior of structures where the following work environments exist: The Models GP21 PPV fans are not simply remakes of units designed to fill changing needs of fire departments. Instead, they are the first to put the PPV concept into a practical package for construction and industrial job sites. Based on confined space ventilation and construction market experience, the General PPV fans were developed with additional size, stability and design features for easier operation.