Instruction manual

7.0 STARTUP SM425 INSTRUCTION MANUAL
Figure 7-17 Display Item Selection
Table 7-2 Display Items
About the air ratio:
“Air ratio” is defined as the ratio of the amount of air theoretically required to completely burn all the fuel to
the amount of air actually supplied.
In the SM425, the air ratio is obtained by measuring the oxygen concentration in the exhaust gas. The air
ratio may be expressed mathematically by:
m = {1 / (21- Oxygen concentration)}
*
21
If the air ratio is used to determine combustion efficiency, etc., verify that there are no air leaks or
interference gases (CH4, CO, H2, etc.) present.
About moisture quantity:
The moisture quantity in the exhaust gas is calculated based on the parameters of the fuel setting (refer
to Section 1.50.3, “Fuel Settings”). The moisture content may be expressed mathematically by:
Moisture quantity = {(water vapor content per fuel unit quantity) + (water content in air)}/ total amount of
exhaust gas
= (Gw + 1.61
*
Z
*
Ao
*
m)/(X + Ao
*
m)
where,
Gw = water vapor content in exhaust gas, m3/kg (m3)
Z= Ambient absolute humidity, kg/kg
Ao= Ideal air amount, m3/kg (m3)
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