Pump piping issues

There are too many questions at once; let’s answer the first two first: 1. It involves a bend with an angle of less than 90 degrees. The vertical pipe ensures perpendicularity, and when the medium comes from above, the horizontal pipe is at the lowest point at the pump inlet. During pumping, the gas in the pipeline at the pump inlet can be smoothly discharged into the equipment ahead； The medium comes from below; the horizontal pipe is at the highest point at the pump inlet. During filling, the gas in front of the pump inlet can be discharged through the pump outlet (vent). 2. Pipe piles are concrete pillars placed on the ground, used to support pipelines. They are positioned at the lowest point, so that the inlet pipeline of the pump is lower in the middle and higher at both ends; this allows gas at the front to be smoothly discharged into the inlet equipment, while the gas at the back can still be released through the pump’s outlet.

3. When the straight section of the pump’s suction pipe is not long enough, flow straighteners or guides should be installed in that short section. What are rectification and diversion? Are there any pictures? I think it involves welding some guide plates or similar items (iron sheets with a certain curved shape) inside the enclosure, in order to prevent vortices from forming and causing cavitation. 4. In the piping layout of reciprocating pumps, when the temperature of the medium being transported is above 180 degrees, the connection pipe to the vibration-damping buffer tank should have a section of unsheathed pipe with a length of around 3 meters. What does this mean? Why isn’t it keeping heat anymore? It is believed that the reciprocating pump cannot operate properly due to efforts to prevent thermal stress from affecting the buffer tank. 5. To prevent cavitation, the pump inlet valve must be larger than or equal to the diameter of the pump inlet pipe; it cannot be made smaller. If the goal is indeed to prevent cavitation, then it’s easier for cavitation to occur at the transition from a larger diameter to a smaller diameter downstream of the inlet valve. This is because as the fluid flows through this transition (from a larger diameter to a smaller one), its velocity increases and its static pressure decreases, which makes vaporization more likely. Sleeves are generally used to match the size of pump connections with that of pipelines. The inlet sleeve usually tapers from large to small, and it can be flush at the top or at the bottom; an increase in speed is intended to reduce vaporization ； Meanwhile, the export increases from small to large, at a decreasing rate, while the static pressure increases. 6. When the operating flow rate of the pump is below 20% of its rated flow rate, a low-flow bypass valve is usually installed. In the diagram accompanying it, the pipe at the bottom of the container is connected to the pump, and there is a branch pipe (bypass pipe) at the pump’s outlet; this branch pipe leads directly back to the container. Since all the flow goes directly back to the container in this case, the flow rate at the pump’s inlet still cannot be increased. The minimum flow line is not about whether the flow rate at the pump inlet is high or low; rather, it ensures that the pump can maintain a certain flow rate even after feed is interrupted, thereby preventing the pump shaft from overheating and failing.

Regarding the first question, if I understand correctly, you are referring to the relationship between the top level and the bottom level at the pump inlet, right? Second question: After reading your answer, I understood it clearly.

I still don’t quite understand the fourth question. Fifth question: You said that increasing the speed can reduce vaporization. How does increasing the speed lead to reduced vaporization? Sixth question: After reading your answer, I understood it

It’s recommended to discuss such issues more with old colleagues!