Piezoelectric cavity pressure sensors

Piezoelectric cavity pressure sensors are suitable for direct use in the cavity due to their physical properties. They are usually installed flush with the mold wall and can be adjusted to the surface by spark erosion or grinding of the sensor front. If installed correctly while maintaining the required drilling tolerances, an error-free measurement of the cavity pressure can be assumed. 

Figure 6.3 The Mark II cavity spectrometer viewed through its Perspex cover. The spatial filter is visible in the centre of the case. The translation stage and piezoelectric actuator are seen in the foreground and operate via the bellows to move the near mirror. The coupling iris is in the centre of the far mirror. The waveguide couplings holding the mica vacuum windows can be seen either side of the case in the background. Sample inlet is on the left wall of the case not visible and outlet is on the right via the pressure sensor...

Nozzle pressure and temperature were measured by pressure/temperature sensor (type 4083A from Kistler). The nozzle sensor was installed at a proper installation hole machined in the nozzle ad tor. A pressure sensor was installed just in front of the gate in toe runner. The pressure sensor in toe runner was type 6157B from Kistler. A pressure/tenperature sensor in toe cavity was installed just after toe gate. The pressme/temperature sensor was type 6190A from Kistler. The sensors in toe cavity and in the runner are piezoelectric type, and toe sensor in the nozzle is strain gage type. 

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