The single-screw pump does not generate sufficient pressure
Thread Content
There are three new single-screw pumps of model G40-1 at the project site, with a head of 60 meters; however, feedback from the site indicates that the actual head achieved is less than 30 meters. Manufacturer’s response: It’s very likely that the inlet and outlet were connected in reverse; additionally, the direction of flow might also be incorrect. If the direction is wrong, there will be pressure as well, but it won’t be high. Are the claims made by these manufacturers reasonable? Also, why doesn’t the new pump achieve the required head once it’s installed?
First, check the pressure regulating valve to see if the head can be increased by adjusting it.
I’ve never heard of a concept of head for screw pumps; if the direction of the screw pump is reversed, it simply won’t be able to deliver fluid
The discharge pressure of a screw pump is related to the characteristics of the outlet pipeline; it is designed to be 6 barg, but the actual pressure reaches only 3 barg. This is likely because too high a resistance was taken into account during design, while the actual pressure required is not that high. If the screw pump is operated in reverse, the fluid will flow back.
A screw pump is a positive-displacement pump. If no fluid is delivered at a height of 60 meters, it indicates that there is excessive backflow leakage inside the pump, which is a problem with the pump. However, if the fluid can be delivered to that height in sufficient quantities, then there is no issue with the pump
A screw pump cannot rotate in reverse; there will be no flow when it does so. This may be due to an excessive gap between the screw and the cylinder, internal leakage, as well as issues related to the inlet diameter, temperature, or the presence of air entering the system.
The inlet and outlet of the single-screw pump are reversed; the inlet is at the bottom and the outlet on the side.
Just look at the direction of the screw at the site, and it’s clear at a glance
When designing a screw pump, the diameter of the inlet is larger than that of the outlet; if they are connected in reverse, it is possible to experience insufficient suction, which can lead to cavitation. This will result in a decrease in flow rate and a reduced lifespan for the pump. If the diameters of the inlet and outlet flanges are the same during design, there should be no problem
A low viscosity at that operating condition can also result in a head pressure that does not meet the design requirements.