chemical tanker operations for the STCW advanced
tank cleanliness
washing water analysis
Non-Volatile matter (NVM)test
spectrophotometers is based on the principle that each chemical compound absorbs or transmits light over a specific range of wavelength.known as electromagnetic radiation ，the methodology provides quantitative analysis.
by measuring the intensity of a beam of light passing through a solution and is used to accurately determine the concentration of a chemical substance contained within the solution.

Methodology
wash water analysis is the complete opposite of wall wash analysis in so much that it is an in-situ identifcation of what is being removed from the cargo tanks during tank cleaning process
rather than finding out what is left behind on the cargo tank walss after the tank cleaning is complete

the following UV trace is a typical tank cleaning operation
at this stage ,there is no nedd to know what the previous cargo is ,or what the particular cleaning steps are .it simply showes what is happening during tank cleaning.