Vacuum systems. Vacuum is space that is devoid of matter. Vacuum engineering deals with technological processes and equipment that use vacuum to achieve better results than those run under atmospheric pressure. The pressure difference produces a force over an area which is called suction. To be exact, suction is the flow of a fluid into a partial vacuum, or region of low pressure. Pumps typically have an inlet where the fluid enters the pump and an outlet where the fluid comes out. The inlet location is said to be at the suction side of the pump. The outlet location is said to be at the discharge side of the pump.