Although a number of books have been written on field instruments for various measurement of process.In this processes such as level, flow, pressure, temperature in a very unique and in a manner suitable for the student or general engineer who has had not got the occasion to specialize in any particular branch.It has been the intention of the authors to fulfill this gap in the existing literature and provide a book which will add value to students, general sales engineers, as well as electronics and instrumentation, control engineers.