The issue of varying diameters at the inlet and outlet of gear pumps
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As shown in the diagram, the inlet of the gear pump has a larger diameter that gradually decreases, while the outlet has a smaller diameter that gradually increases. Why is it designed this way? Also, I’m seeking advice regarding imported eccentric tees with a flat bottom…
A heavy medium pump, with electric heating too! The change in diameter for imports and exports is mainly influenced by the equipment; once that is determined, you can’t connect things if there’s no change in diameter
No, it’s just the design – all gear pumps are built this way
It can be understood from the aspects of pipeline resistance and the impact of flow velocity on overall pipeline fittings, for reference.
The diameter of the pump’s inlet pipe must take into account the pump’s suction height and net positive suction head; therefore, it is generally made larger than the pump’s inlet pipe diameter. The diameter of the outlet pipe needs to take into account factors such as the pump’s head, the resistance of the outlet pipes and fittings, as well as energy consumption; it is generally larger than the pump’s outlet diameter. An eccentric reducer is used for the inlet, as the inlet pipeline is arranged horizontally – this helps to prevent vortex formation at the inlet and also to avoid fluid accumulation when the pump is not in use.
That makes sense, but the net positive suction head shouldn’t be correct; it’s a gear pump, not a centrifugal pump
From two aspects, the design of the gear pump takes into account the dimensions of its inlet and outlet; these lengths are short as well, and the flow velocity of the medium has little impact on it, so meeting the requirements of the pump itself is sufficient. The inlet pipe of a pump generally operates under gravity flow, so the flow velocity is relatively low; as a result, the pipe diameter can be larger, which in turn reduces the pipe resistance. As for eccentric reducers, it’s easy to understand once the principle of gradual increase and decrease is followed. For the pump outlet pipeline, the medium flow rate and pipeline pressure drop are the main factors to consider; after selecting the pipeline, the pressure drop is calculated as well, taking economic considerations into account. For further information, please study the SHT3035-2007 Guidelines for Selecting Pipe Diameters in Process Units of Petrochemical Enterprises, or the Manual for the Installation and Design of Process Pipes in Petrochemical Plants
I think it’s for the purpose of piping. Is this a ROTAN gear pump?
At the pump’s rated power, the flow rate, velocity, and head of the medium remain constant; the diameter of the pipe affects the velocity of the medium within it, but has no impact on other aspects.
The eccentric reducer at the inlet has been discussed by experts on the forum: https://bbs.hcbbs.com/thread-914738-1-1.htm https://bbs.hcbbs.com/thread-550646-1-1.html