Siemens SIPROCESS GA700 - How the CALOMAT 7 Works; CALOMAT 7 Measurement Task

Description
3.4 CALOMAT 7
Operating with the Local User Interface
28 Operating Manual, 06/2017, A5E31930478-05
3.4.2
How the CALOMAT 7 works
Overview
①
Sample gas inlet
②
Measuring membrane with
thin-film resistors
③
Sample gas outlet
Figure 3-6 Principle of operation of CALOMAT 7
How it works/measuring principle
The measuring method is based on the different levels of thermal conductivity of gases.
CALOMAT 7 analyzer modules work with a micromechanically produced Si chip, the
measuring membrane of which is equipped with thin-film resistors.
The resistors contained in the membrane are regulated for constant temperature. The
amperage required fluctuates in accordance with the thermal conductivity of the sample gas.
This raw value determined in this way is processed further electronically to calculate the gas
concentration.
The sensor is in a thermostatically controlled stainless steel enclosure in order to suppress
the effect of the ambient temperature. To rule out flow influences, the sensor is mounted in a
bore hole next to the flow channel.
3.4.3
CALOMAT 7 measurement task
Overview
The following gas components can be measured with CALOMAT 7 analyzer modules.
Table 3- 3 CALOMAT 7 measurement task
Num
ber
Gas mixtures (measurement of...)
19
Hydrogen in helium
20
Helium in hydrogen
21
Hydrogen in methane