35
RPM:
Revolutions per minute of the engine as detected by the induction pickup clamp. This probe is
plugged into the two connector on the bottom of the instrument case, ensure correct polarity. NOT
FITTED (N/F) will be displayed if the probe is not connected.
LAMBDA:
The value of Lambda gives an indication of the burning efficiency of the engine. This can be
replaced with the Air Fuel Ratio (AFR) below. See Units Menu (Section 5.2.3) to change between
displays. Appendix B gives the formula used.
When sampling fresh air and lambda is outside operation range this indication will show ‘-----‘.
AFR:
Air Fuel Ratio is another method for displaying the efficiency of an engine. The calculation for the
AFR is Lambda multiplied by 14.7 for Gasoline and 15.6 for LPG (typically). When sampling
fresh air this indication will show ‘-----‘.
NO:
Nitric oxide reading in ppm (parts per millions) of the exhaust gas. Displayed when Nitric oxide
sensor fitted, indicated on the rear label. Displays NOT FITTED or N/F when sensor not fitted
and FAULT or FLT if failed.
NOx:
A calculated value based on the measured level of Nitric Oxide to display total oxides of Nitrogen.
LOW FLOW:
During sampling or at any time the pump is running the screen may display LOW FLOW.
PUMP OFF:
Indicates the pump has been manually turned off using the key.
TIME TO:
The analyzer requires to regularly zero the sensors. Once a zero has been performed the time to
ZERO
the next zero is displayed in minutes. Check there is sufficient time remaining before starting a
test and perform a manual zero if not.
B - LAMBDA CALCULATIONS
The value for Lambda is a determinant for the burning efficiency of an engine. The value depends on the
composition of the fuel, the air that is used for the combustion and on the combustion products as found in
the exhaust gases.
This formula takes into account the following:
• Components of the fuel: carbon, hydrogen, oxygen and water content;
• Water content of the air;
• Components of the exhaust gases: carbon dioxide, carbon monoxide, hydrocarbons and
nitrogen oxide;
Developed by J. Brettschneider and published in Bosh Technishe Berichte, Volume 6 (1979), No. 4,
page 177-186.
