I’m a Spanish student and I have to translate a text about pumps. Since I’m not an expert in the subject and I haven’t found any useful English text about it, I would like you to help me clarify some concepts about steam or gas pressure pumps. The text says that the operation of the inert gas pumping is a cycle that has the following stages or phases: 1. Filling phase. The air goes out through a stop tube and a discharge tube. A ball valve opens and consequently the liquid can reach the sump. 2. Filled phase. The liquid reaches the top of the stop tube that gets full; the pressure of the air raises, the ball valve closes and the ejection starts through the vertical discharge tube. 3. Discharge phase. The pressure of the air keeps being constant, the ball valve is still closed and the ejection continues. 4. Discharged phase. The level of the liquid goes down until the curvature of the stop tube and the air escapes with a big impulse through the stop tube and the discharge tube. The liquid reaches an atmospheric pressure so the ball valve opens and a new cycle starts. My question is whether this four-stage cycle could be summarized into two stages, the filling stage and the discharge stage, since this is what I understand from the original text. And also, I am not sure about the terminology I have used, I hope you can get the main idea and please don’t hesitate to correct anything you consider wrong! Thank you indeed for your help!