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Gas flow diagram, Figure 3 – M&C TechGroup PMA 50 EEX Operator's manual User Manual

Page 16

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16

Gas sampling and gas conditioning technology

9-3.15-ME

Every change of the oxygen concentration produces a lineary proportional change of the com-
pensation current and can be read directly in % O

2

as oxygen value on the display .


Due to its very small stagnant volume (2 cm

3

) and the direct flow of the M&C measuring cell, an

extremely fast response time (T

90

-time) of 1 second for a high gas flow can be realized.



13

GAS FLOW DIAGRAM

Figure 3 shows the gas flow diagram of the Oxygen Analyser PMA 50 Ex.

1 : External fine filter

2 : External flow meter

3 : Ventilate arrestor

4 : Measuring cell

5 : Flow alarm sensor

6 : Ventilate arrestor

3

4

5

6

2

1

Figure 3

Gas flow diagram


The measuring cell 4 must absolutely be protected against dust particles. Therefore, the preced-
ing external gas conditioning system should be equipped with a fine filter 1 of at least 2 micron
filter porosity (eg. type FP-2T).

The maximum gas flow of 60Nl/h is adjusted via an externally mounted flow meter 2 with needle
valve.


The sample gas enters the measuring cell 4 via the inlet ventilate arrestors 3.

A flow sensor 5 in the outlet of the measuring cell is controlling the gas flow through the cell a c-
cording to the measuring principle of thermal conductivity. In case the minimum gas flow is d e-
creased, an alarm is automatically given and is available as status alarm on the the collective
status output. Furthermore, an alarm state is shown by a colour change of the LED 4 (see figure
1) on the front plate of the analyzer.