The GTL belt-driven, single-inlet centrifugal fans cover air flows up to 27 m3/s and pressure rises up to 3300 Pa. The fans are available with different types of impellers:
Impellers with forward-curved blades (GTLF fans)
Impellers with backward-curved blades (GTLB fans)
The backward-curved blades in the GTLB fans have the same aerodynamic characteristics as those in the GTHB fans, but the GTHB blades are a reinforced version for higher speeds.
Besides the normal version, the fans are also available in a sparkproof version. The smoke extraction version of GT has been tested by the French CTICM institute and by the Russian VNIIPO institute. CTICM has tested the fans for +400 °C, 2 hours and the tests cover GTLB-3-025–140 and GTLF-3- 031–071. VNIIPO has tested the fans for +400 °C, 2 hours and for +600 °C, 1 hour and the tests cover all single-inlet GT-fans. The fans in the smoke extraction
version have metallic bearing dampers. The fans in the spark-proof version conform to the German standard VDMA 24 169 3.1 – 3.2 and 3.4. The inlet cone is made of brass. In the GTLF fans, the inlet is fitted with a brass band. If the inlet of the fan is connected to the ducting, the single-inlet fans are rated for continuous operation at temperatures up to +80 °C. If the motor is exposed to the air stream (i.e. on a free-inlet fan), the ambient temperature must not exceed +40 °C. Motors for higher temperatures are available on request.
The casing is made of Sendzimir-galvanized sheet steel. The casing is jointed by the "Pittsburg folding method", which produces tight, strong joints.