Pressure issues at the inlet and outlet of the pump

Take a photo of the nameplate on your pump and send it over for me to take a look. Specifically, it depends on the design pressure of the pump body (as well as that of the mechanical seal). If the operating pressure is below these design values, there will be no problems; however, if it exceeds these design pressures, there are significant operational risks. In addition, you also need to check the design pressure of your outlet pipeline to ensure that it is not subjected to excessive pressure. It’s even more dangerous when the pressure gauge reaches its full scale.

Agree with what was said above; it is indeed necessary to consider the issues mentioned.

Generally, the design of a pump is related to the medium it handles

Agree with what was said on the 3rd floor: it is necessary to check whether the pressure-bearing capacity of the pump itself is sufficient, and also to ensure that the design pressure of the pump’s outlet pipeline meets the required standards

It is not recommended to use it in this way, as excessive pressure will increase the load on the pump and may affect its sealing performance. It is recommended to choose a different model; it won’t cost much. But if an accident does occur, things will get serious.

It is also necessary to consider the pressure and corrosion resistance of the sealing rubber rings and sealing surfaces, as well as whether your prime motor can withstand the load and grid voltage

There will definitely be an impact; there is head at the pump inlet, so the pressure when the pump starts operating will surely be high. If you don’t want to replace the pump, you can try the following method to determine whether it can still be used: install a pressure gauge with a larger range, start the pump, check the pressure at the pump outlet and record it. Determine the head specified on the pump’s nameplate, and calculate using the formula 0.1 MPa = 10 m of head. Compare this value with the actual outlet pressure. Have the electrical technician check whether the motor current exceeds the rated value. If the pressure is too high or the current is too high, then do not use this pump. If neither of these issues exists, then open the outlet valve to adjust the outlet flow to the desired level; this will reduce the pressure. Have the electrical technician check the current again. If it still exceeds the rated value or is close to it, then the pump still cannot be used. If the current is within the normal range, then the pump can be used. Once it is confirmed that use is possible, have the mechanic replace the mechanical seal with a high-pressure-resistant seal such as a bellows, or use the 53a or 53b flushing method. During regular inspections, pay attention to any changes in the color of the lubricating oil; if the color turns black, it may be due to wear on the bearings that are subjected to axial loads as a result of excessive axial forces. These bearings will need to be replaced during subsequent maintenance. Consider the design pressure and material of the pipe, and consult relevant documents for further information

You need to check the specifications of that pump to find out its allowable inlet pressure or maximum operating pressure.

This post was last edited by H-drizzle on 2016-7-1 at 13:30. First, regarding the issue of excessive current mentioned above, a high pressure at the pump inlet necessarily leads to an increase in outlet pressure. Even if the liquefied gas medium changes, the density generally does not change much. However, there may be specific requirements regarding the pressure at the pump outlet, as the pressure has risen from 1.7 MPa to at least 2.5 MPa (>=2.5–1.7). This indicates that the current operating head is already equal to or even exceeds the head required for transporting the original medium (1.1–0.3). Therefore, the density change is minimal, and the flow rate can only decrease rather than increase. It is assumed that the motor load will not exceed its limits, so this aspect is not considered a key factor. Secondly, there is the issue of flow rate. At this point, it is possible to simply calculate the rated head of the pump; since the actual operating head increases, if the rated head is too low, it is necessary to consider whether the required delivery volume and delivery time can still be met according to the process specifications. Third, the view expressed on the 3rd floor is absolutely correct and hits the core of the issue: the motor is not the problem; the issues lie in the design pressure and sealing performance of the pump, as well as those of the pump’s outlet pipes. Regarding the design pressure of the liquefied gas pipelines, designers generally determine it by referring to the saturated vapor pressure of a medium with a higher vapor pressure than the one in question under the most severe temperature conditions, which allows for an approximate estimation. Additionally, all outlet pipes at the pump outlet should be equipped with pipe safety valves. Furthermore, the claim regarding an estimated head of 10 floors is incorrect; liquefied gas is different from water, and it cannot be converted using the formula of 0.1 MP = 10 m. The above are merely my personal opinions; if there are any errors, I hope **you can correct and guide me. The consequences of liquefied gas transmission leaks are extremely serious and life-threatening; it is necessary to conduct inspections and take action as soon as possible.