4.18 Measuring FGR
FGR principle monoblock ver. 3
Pos.
Item
1
FGR duct
2
FGR control valve
3
Measuring point of residual oxygen in
flue gas
Recirculated flue gas amount is typically 5–20 % of the flue gas/combustion air mixture
amount, depending on the application. Flue gas percentage is counted as follows:
FGR % = Flue gas amount recirculated ppm / (Flue gas amount recirculated ppm +
combustion air amount in ppm) %
To define flue gas percentage
1. First measure the amount of O
2
in the flue gas/combustion air mixture. The optimal
measuring point is the burner wind box.
2. Measure the residual O
2
in flue gas.
3. Read the FGR percentage value in the diagram below.
M4248 2316EN
63 (114)
