The purpose of this work is to realize a vacuum gauge for use in
dry air. Based on the hot wire anemometer principle and using a
micro thermocouple of 25.4
mm diameter, this gauge presents a weak response time (cut-off frequency of 5 Hz) and it is inert. The
local temperature information of the sensor can be deduced from
the relaxation cooling period while the signal frequency allows to
access to the vacuum pressure information. At the end of the
heating period t
h
the temperature of the Th
micro thermocouple
tends to that of the fluid temperature T
f
sens
. The experimental characterization
has shown that the optimum functioning is obtained
with low heating duration. The measuring range is 10
Pa
and the pressure sensitivity is good between 5 and 10 Pa and 2e
3 kPa. The best sensitivity in air is obtained for values of heating
current I
c
of 12 mA and heating duration t
of 40 ms. It has been
established that the sensor has a the best sensitivity S of 12.8 mHz/
Pa for vacuum in the range 30 Pae300 Pa and measures pressures
up to 10
5
h
E. Gavignet, F. Lanzetta / Vacuum 100 (2014) 18e21 21
1
Pa.