Dear Mahmud, both API and ...
Published by Marco Rognoni, Owner at WET, Water Edge Technologies
Dear Mahmud,
both API and CPI are based on the same principle of the gravity separation based on the difference of density between oil and water. Hence the field of applicability is the same.
Actually the design of each of them is guided by the same code API 421 and I recommend you to study it and find many answers there.
API is normally used for the primary treatment of high oil concentration and reduce it before other separation treatment steps.
CPI is normally preferred when the inlet oil concentration is below 1000 ppm and can be reduced eventually to less than 50 ppm (efficiency 95% typically higher than API).
API is a large basin which requires large land whilst CPI is a more compact package unit which can be fabricated at shop and easily installed at site, ready to work. Hence CPI is preferred in the majority of cases.
2 Comments
Yes this is correct and I agree with Marco and Rafael's minor correction, albeit important...
Published by Gary Brown, Water Practitioner at Dikubu Water
Just a clarification, while API is based on experimental work for droplets of 150 micron dia. and Stoke's law, CPI is based mostly on a theoretical approach to plates on basis of the Stoke's law. For the rest I fully agree with Marco.