Problems that occur during flushing and pump testing
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Problems that occur during flushing and pump testing: Phenomenon 1: When lifting water to a higher level, after water starts flowing out of the high-point vent valve, close that valve. Start the high-point water circulation pump (located on the ground floor), open the inlet and outlet valves of the pump fully, and find that the pressure at the pump’s outlet is only 0.7 MPa. Open the high-point vent valve again, and discover that air is being drawn into the high-point water pipeline. Phenomenon 2: After the above situation occurred, our actions were as follows: we stopped the high-pressure water circulation pump and restarted the supply of high-pressure water. We waited until water flowed out of the high-pressure release valve for a considerable amount of time before closing it. We then opened both the inlet and outlet valves of the pump, but the pressure at the pump’s outlet was still only 0.7 MPa. Therefore, the outlet valve of the high-pressure water circulation pump was closed to keep the pump outlet pressure at 1.0 MPa. After a while, the pressure began to rise, so the pump outlet valve was gradually opened wider. Once again, slowly open the high-point drain valve, and water was observed flowing out from this valve (with some bubbles in the water). As the pump testing proceeded, the pump outlet valve was opened wider and wider until it was fully open. It was found that the pressure continued to rise (touching the high-pressure water pipes showed that their temperature was slightly higher than the ambient temperature). When the pressure reached 1.8 MPa, due to the limitations of the explosion-proof plate and safety valve, drainage from the pump outlet was used to prevent further increases in pressure. How can the above phenomenon be explained?
This post was last edited by ljc9 on 2010-1-25 at 21:52. It might be pump cavitation, but the cause needs to be analyzed in detail. For a circulating water pump, it could be that the gas in the water circuit has not been completely removed, or there are no venting facilities in the return water pipeline, allowing the gas in the return water circuit to enter the pump directly through the pump’s inlet pipeline. This is true assuming that you don’t have a circulating water tank and that the return water line is connected directly to the make-up water line. After the pump starts operating again, if the time for venting at the highest point is long enough and the outlet valve of the pump is closed sufficiently, the gas in the pipeline can be removed through venting at that highest point, resulting in normal operation. If this assumption is correct, there are some phenomena that the original poster did not explain clearly
Friend of the poster, it can’t be that complicated. Next time you fill the high-pressure system with water, you need to open the inlet/outlet valves of both pumps (is there a check valve on the outlet? Actually, it’s not necessary). Also, open the exhaust valve at the high pressure point to ensure that the high-pressure system is fully filled with water (otherwise, water will only fill one side). Only then can you start the pumps normally. After the circulation pump starts (or before it starts), the high-pressure system must be connected to the pressure stabilization system; otherwise, overpressure will occur as the temperature rises.
Poster: Follow the procedures outlined on floor 3. Additionally, as you mentioned, open the outlet drain to release some water when overpressure occurs; pay close attention to the outlet pressure of the pump – shut it down immediately if the pressure is normal, otherwise more water will need to be added!
I agree with the view above; it is likely due to insufficient water level, the pump starting too early, gas present in the pump inlet pipeline, or an inadequate suction flow rate by the pump. Generally, it can be determined from the pump’s outlet pressure, vibration levels, noise, as well as the vibration and noise of the connecting pipelines. When refilling with high-purity water, open the inert gas vent valve on the side of the high-pressure washer housing, slightly open the inlet and outlet valves of the pump, and then start the pump after the tank is filled.
Dear sea friends, please explain “Phenomenon 1”. Why does a vacuum form in a high-pressure water system, causing air to be drawn in?
This post was last edited by Xieshui on 2010-1-31 at 11:38. The system wasn’t filled with water before starting the pump. My friend, it’s working properly now, right? If there are any problems, let me know; maybe I can help.
To fill it with water, it is necessary to ensure that the entire pipeline is connected.
At a height of three floors, the designed water system features a high-pressure steam drum; in some designs it is connected to the liquid outlet of the high-pressure steam drum – one purpose is for water supply and the other is for pressure balance, so connectivity is necessary.
You’re too kind upstairs. In the past, pressure-stabilizing pumps were used in high-pressure water systems; their functions were to replenish water and balance the pressure. Nowadays, this design is mostly abandoned in favor of using only pressure-stabilizing valves, which also serve to replenish water and balance pressure. However, it is necessary to keep these valves open, otherwise the burst disk cannot withstand the fluctuations in water pressure and may burst.
6# Wang Li: The reason is that the high-pressure water system was not filled with water. When the pump started, the gas inside was compressed, and the water failed to return to the pump’s inlet in time. As a result, the flow rate out of the pump exceeded the flow rate returning to its inlet, creating a vacuum area on the inlet side of the pump (a vacuum usually forms at the top of the high-pressure washer).