Why does a turbidimeter need to be calibrated?
Purpose of calibrating a turbidimeter
The light source used in turbidimeters has a specified temperature (required by USEPA regulations) at which it is required to operate. Because these lamps operate at a relatively high temperature, the output of the lamps can change over time, which can affect the amount of light that reaches the detector and thus the turbidity reading. Hach lamps are specially designed for increased stability and are stable upon factory calibration. However, USEPA regulations mandate calibration upon receipt and set up of the instrument at the test site, as well as calibration on a quarterly basis.