How to maintain a constant outlet pressure in diaphragm pumps
Thread Content
I need to conduct a filter test using a plate and frame filter in the laboratory, and it is necessary to maintain a constant pressure in the filter. For the transfer of the liquid mixture (pressure supply equipment), an electric diaphragm pump is used, with a flow rate of 0.75 m3/h and a rated pressure of 0.3 MPa. I would appreciate guidance from experts on how to design the pipeline system between the pump and the filter so as to achieve a constant pressure level of 0.2 MPa. I have looked up relevant information, such as the use of buffer tanks and pulse dampers, etc., but I’m not sure which solution will work.
Imported dampers, outlet buffer tanks
We also need to use plate and frame filtration, and we have to use diaphragm pumps to feed the material. However, it seems there is no specific requirement regarding pressure; it’s sufficient as long as the inlet pressure meets the requirements specified by the plate and frame filter manufacturer. It appears that the situation we face is a bit simpler than what the client has in mind. I’m not very familiar with diaphragm pumps; once such a pump is chosen, its head pressure remains constant, right? Positive displacement pumps do have this characteristic, don’t they?
A bypass line for inlet and outlet can be designed, using its opening degree to regulate the pressure at the pump outlet.
Flow pulse, constant pressure energy?
A damper with a backpressure valve should be able to solve the problem
A single buffer tank cannot solve the problem
Generally, diaphragm pumps have a relatively low outlet pressure and cannot withstand high pressures; such pressures can easily damage the diaphragm. They are not suitable for feeding plate and frame filter presses. They can be used with small-sized plate and frame units, but for larger ones, other types of pumps need to be considered
In laboratory experiments, it is probably necessary to determine the resistance value of the sludge. The inlet pressure is required to be constant. Fortunately, electric diaphragm pumps can use frequency conversion, along with a pressure transmitter at the outlet. It’s difficult to design it if it’s a pneumatic diaphragm pump.