Who has the schematic diagram of a positive displacement pump?
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Today, while checking out the new installation, I noticed that there was no valve at the inlet of a vertical pump. I asked the workers in the workshop, and they said it’s a self-priming pump, so an inlet valve isn’t needed. When I saw that the efficiency was 75%, I realized that my knowledge still dates back to the era when self-priming pumps were considered to be more than 20% less efficient than centrifugal pumps. I was completely stunned at that time! Can a self-priming pump have such high efficiency? Moreover, the required cavitation pressure is only 1.5M! ! I still haven’t found the manual for this pump in the archives. . . I checked online and it seems to be called a exhaust pump. I’m quite curious about its structure
The original poster should take some photos, such as pictures of the actual pump and its nameplate. Only then can we help. . .
The absence of valves at the inlet does not mean that there is no backflow prevention mechanism inside the pump. Where did the claim of a 20% difference come from? For high-volume pumps with high volumetric efficiency, such a large difference does not exist; vertical pumps generally have very low net positive suction heads
Why doesn’t the original poster post a photo and the pump model? Learn* learn*
Discussions about synchronous exhaust pumps date back to 2012; I only learned about such pumps today. I’ll go to the site in a bit to take some photos. What I mainly want to know is the internal structure of these pumps. Without a manual, I’ll have to wait until the pump breaks down before I can take a look inside it.
The pump factory says it has a patent and won’t provide the structural diagram; L, we can look at the principle once it breaks down later. . . I haven’t found any relevant structure diagrams these days either