Cxhy Sensor For Measurement Of The Unburned Hydrocarbons; Installing The Cxhy Sensor - E Instruments E4500 Operating & Maintenance Manual

14.6 CxHy sensor for measurement of the Unburned hydrocarbons

The Unburned hydrocarbons are chemicals produced by an incomplete combustion of molecules (hydrocarbons)
made of Carbon and Hydrogen.
These are usually named as HC or (better) CxHy: when this is filled with the actual values for the number of C
and H atoms, the actual type of fuel is exactly defined. In case of Methane, as an example, the correct formula is
CH4. In the following table is shown the cross sensitivity of the CxHy sensor when exposed to fuels different from
Methane (CH4), assumed as 1.00.
GAS / VAPOR
Ethanol
Iso-Butane
Methane
Methanol
n-Butane
n-Heptane
n-Hexane
Propane
Calculation example:
Type of gas:
Relative response:
Gain adjustment:
Reading value (related to metane):
Value = reading value x gain adjustment
Example: 1.34 x 1.67 = 2.24

14.7 Installing the CxHy sensor

When the CxHy (position S3/S4) is mounted in the instrument, it is mandatory to configure the autozero by set-
ting it at 180 seconds, in order to allow for a proper pre-heating of the sensor itself.
The instrument battery life, once the CxHy is installed, lasts 10 hours, provided no printing is made.
Configuration→Analysis→Autozero (SEE SECTION 9.2.6)
07/08/14
10:00
Configuration
Autozero
Autozero
60
s
Purging
0
s
O
RELATIVE RESPONSE
(with respect to Methane)
iso-butane
0.6
1.67
1.34
07/08/14
10:00
Configuration
Autozero
Autozero
060
s
Purging
0
s
O
OK
0.75
0.60
1.00
1.00
0.60
0.45
0.50
0.70
Configuration
Autozero
Autozero
s
Purging
s
O
OK
122
GAIN ADJUSTMENT
1.33
1.67
1.00
1.00
1.67
2.22
2.00
1.43
07/08/14
10:00
Configuration
Autozero
Autozero
180
s
Purging
0
s
OK
K000000000EJ 023826A0 100714
→
07/08/14
10:00
180
0
O