This book is based on the basic knowoledge of chemical process control of temperature , pressure, level and other variables. Analysis of the data of back days for early fault detection and diagnosis . Analysis is carried out by visualization of these variable through parallel coordinate plot on the Visulab software. Images are shown for understanding. Data is taken from the website of university of california, irvine . which is of the waste water treatment plant located at catalonia spain. Data is of the years in 19's.