The Pneumatic Fixed Mirror System is the most commenly required Pyrometry system used to scan over a range of heights on the blade surface in turbines where temperatures are below 1400C.
The system is most suited to this application. A pyrometer probe with a fixed mirror is mounted in a pneumatic actuator. The sight tube diameter is 8mm enabling standard borescope holes to be used. The pyrometer probe can be easily removed from the actuator allowing switching between tubes with different viewing ranges. The scan range is determined by the postion of the limits on the pnuematic drive. The maximum scan depth is determined by the ability of the sight tube to withstand the physical and thermal stresses encountered in the gas stream. The fixed mirror angle is set to view within the required blade height range. Data is collected continuously while the pneumatic drive inserts and retracts the sight tube. As the pyrometer probe is inserted, the viewing area moves down the blade. As the blades rotate, the viewing area moves across the blade.