Apply the Kremser absorption/stripping factor method for dilute systems and packed/tray column HETP / efficiency screening. Use when sizing an absorber or stripper, estimating per-stage performance for a dilute solute, or sanity-checking a vendor sizing. Don't use for reactive absorption with chemical equilibrium (use sour-gas-amine-treating), highly concentrated systems (Kremser assumes dilute), or rate-based packed-column design with detailed mass-transfer correlations.
