Ecom EN3 Instruction Manual page 49

Internal
Air leak test
NOTE
The term "undiluted" refers to the conversion of the gas concentration
to a definable reference oxygen content according to the following
formula:
NOTE
mg/kWh and mg/MJ are always calculated on 0% O2 basis.
ecom-EN3
Further instrument settings
-- see following table --
Check the tightness of the instru-
ment (see chapter "Air leak test")
E = E
ref meas
21 – O
2ref
*
21 – O
2meas
Page 49