The pressure drops as soon as the outlet valve of the centrifugal pump is fully opened; sometimes this even leads to the destruction of the mechanical seal. Please help analyze it.
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Yang Cheng: 50 traffic, 30. The pipeline layout is as shown in the figure below; do anyone have any good suggestions?
Can a siphon tank be equipped with a level gauge? Normally, the fewer sealing points there are in the inlet pipeline, the better.
The length of the pump inlet pipe is too long, and the volume of the siphon tank is too small; it should be 3-5 times the total volume of the pipes.
3-5 times the total length of the suction pipeline; can I install a level gauge on it?
It’s not necessary; it’s enough to see water coming out from the top of the tank when filling it with water.
I’m worried that if something goes wrong, the liquid level in the tank won’t be able to be replenished in time, which could damage the mechanical seal
The resistance in the inlet pipeline is too high, resulting in a low net positive suction head; it is possible that cavitation will occur as soon as the pump starts (this can be determined by checking the motor current or listening to the sound of the pump).
The length of the pump inlet pipe is too long, and the volume of the siphon tank is too small; it should be 3-5 times the total volume of the pipes.
There is some backpressure at the outlet; if there is no pressure at the outlet, it’s normal for the pressure to drop when it is increased
It’s a shock to see it – it really resembles the layout I designed for a manufacturer back in the past. In my design, I placed the tanks on their rooftops. In your case, the inlet pipeline of the centrifugal pump is quite long, so the tanks seem a bit too small. Also, check whether there are any leaks in the pipes of the pump’s inlet pipeline or in the siphon tank. In fact, using a centrifugal pump under such conditions is quite demanding. What kind of fluid are you transporting? I suggest that you go ahead and install a non-negative pressure water supply system, just one set – it will give better results.
I took a close look at your inlet pipes – the thick ones are thick and the thin ones are thin. The reasons for seal damage and pressure drop are both insufficient liquid supply from the pump! Improvement method: The diameter of the inlet pipe should not be smaller than that of the pump’s inlet; it’s fine if it is larger.