When a circuit design is in the planning stages, it is much more than determining what the real purpose of the system is going to do. Look at the application and think, how are we going to achieve our goal? What do we want this system to accomplish? You start by selecting components, like valves, hoses, pipe, pump, motor, actuation, filters, reservoir, and other components and layout. You include your initial cost of building the system, step back and you feel like you really accomplished something and reached the mountaintop! There are a few other factors to consider, however. There is weight, cost of operation, ease of maintenance, machine duty cycle, and replacement components to have on hand for emergencies.