Four different levels of analytical schematics of pump and motor models exist, arbitrarily numbered as Type 0 through Type 3, each one progressively more complex and more inclusive. Type 0 Models are ideal because they contain no losses. They are perfectly efficient, having 100% volumetric, mechanical, and overall efficiencies. They are referred to in industrial jargon as models for calculating the “theoretical” performance of pumps and motors. More-practical models include the theoretical imperfections encountered in the real world.
In analytical schematics, the idealized portions of the circuit are identified with an I inside the pump or motor symbol. The elements associated with losses are characterized as being external to the idealized elements. As more of the real performance of real machines is incorporated into the models with more and more theories, the model actually becomes more practical, not more theoretical, assuming, of course, that the modelers have applied the various theories correctly.