EWL flow compensation

As for oxygen consumption and CO₂ production, calculation of evaporative water loss necessitates compensation for the change in flow rate induced by the animal's metabolism -- oxygen uptake and CO₂ emission -- as well as by evaporative water loss itself. This can be done in three ways:

If the file contains data on both oxygen and CO2 concentrations (the former baselined so that 20.95% oxygen = zero), select 'Use [O2] and [CO2]'. The program will read F_eO₂ and F_eCO₂ from the appropriate channels, selected from subsequently-opened channel selection windows.
If the file contains data on oxygen concentrations (baselined so that 20.95% oxygen = zero) but not CO₂ concentrations, select 'Use [O2] and RQ'. The program will read F_eO₂ from the appropriate channel, selected from a subsequently-opened channel selection window. F_eCO₂ is computed from F_eO₂ via a user-entered RQ value.
If the file does not contain data on either oxygen or CO₂ concentrations, select 'Use constant [O2]' and enter a value for F_eO₂. F_eCO₂ is computed from that F_eO₂ via a user-entered RQ value. If you are ONLY measuring evaporation from something that does not emit CO₂ or absorb O₂, then use this option and enter .2095 for F_eO₂.

You will also need to provide data on the water content of incurrent gas (F_iH₂O, the fraction of gas entering the metabolism chamber (or mask) that is comprised of water vapor). You can enter this directly if you know it, or use the 'Estimate FiH2O...' button to calculate it from the window shown at right. In either case -- unless incurrent gas is dry (RH = zero) -- you will need to have some measure (relative humidity, vapor pressure, etc.) of the water content of incurrent gas. The program will compute excurrent water content (F_eH₂O) based on the humidity channel and units previously selected.

go to: