Vaisala PTB210 SERIES Manuel d'instructions télécharger pdf (Page 24)

measurements. Upon every maintenance visit, one of the barometers should be

replaced with the recalibrated spare one. This way you can ensure that there is a

maximum in accuracy and precission for further calculations.

Measuring Principle

The PTB210 barometers incorporate the BAROCAP silicon capacitive absolute

pressure sensor developed by Vaisala [8] . The BAROCAP principle can be found in

2.13. The sensor features excellent hysteresis and repeatability characteristics and

has an outstanding temperature and long-term stability.

Figure 2.13: The BAROCAP Pressure Sensor

[Manuel - PTB210 Digital Series with Serial Output, 12/05]

The sensor consists of two layers of single crystal silicon having a layer of glass

between them. The thinner silicon layer creates an integrated vacuum reference

chamber and forms a pressure-sensitive silicon diaphragm. The thicker silicon layer

is the rigid base plate of the sensor and is clad with a glass dielectric. Thin ﬁlm

metallization is deposited to form a capacitor electrode inside the vacuum reference

chamber. The other electrode is the pressure-sensitive silicon diaphragm. When

pressure changes, the silicon diaphram bends and changes the height of the vacuum

gap in the sensor. This changes the capacitance of the sensor which is measured

and converted into a pressure reading [18].

1 2 ... 19 20 21 22 23 24 25 26 27 28 29 ... 136 137

Pas de commentaire

Vaisala PTB210 SERIES Manuel d'instructions Page 24