The factor on a UnitConversion is the single number piper multiplies against an incoming result value to produce the normalized concentration. For ug/L to mg/L the factor is 0.001; for mg/L to ug/L it is 1000. Getting the factor right is critical for compliance accuracy — a factor error would cause all threshold comparisons using that conversion to report incorrect exceedance ratios. The factor is always applied as: converted value = original value multiplied by factor.
Technical section
Data model, API, and internals — visible to developers.