Siemens AG
7 Safety Manual CALOMAT 6 Gas Analyzers
07/2010, A5E00729184-02
Control System
Figure 2-1 Example of a safety-instrumented system
Function
The measuring principle is based on the different thermal conductivity of gases.
The CALOMAT 6 operates with a micro-mechanically manufactured Si chip whose
measuring diaphragm contains thin-film resistors.
The resistors are regulated at a constant temperature. A current is required to
achieve this, and its magnitude assumes a particular value depending on the
thermal conductivity of the sample gas. This raw value is subject to further elec-
tronic processing and is used to calculate the gas concentration.
To suppress ambient temperature influences, the sensor is located in a thermo-
statically-controlled stainless steel housing.
To prevent flow influences, the sensor is only subject to an indirect flow
Special characteristics
- Four freely-programmable measuring ranges per component, also with sup-
pressed zero
- All measuring ranges linear!
- The isolated analog output is set to 4 to 20 mA (NAMUR)
For safety instrumented systems the relay output is used for diagnostics only.
To Next Page
Loading...
