scourtland wrote:Hi There,
I am trying to convert 5 NTU to the equivalent expression in % transmissivity. Is there a way to convert these units?
Because the optical measurement methods are different, the readings of a transmissometer and a nephelometer cannot be directly related - there's no table that converts NTUs to percent transmission for all waters.
For purposes of rough estimation, though, percent transmission can be related to NTUs as defined by formazin dilutions. For a transmissometer with a path length of 10 cm, the span of 20% to 80% transmission corresponds roughly to a turbidity span of 230 to 20 NTUs. For a 25-cm path length, the turbidity span is 60 to 10 NTUs.
Practitioners can relate NTUs and percent transmission for their particular waters only by comparing nephelometer readings with transmissometer readings for a number of samples, and generating a custom conversion table or algorithm.