Without back pressure, a metering pump cannot simultaneously meet both flow rate and pressure requirements!
Thread Content
There is no back pressure in the pump outlet pipeline. When performing a single test of the metering pump, it was found that the flow rate and the pump’s outlet pressure cannot both be satisfied simultaneously; I’m not sure what causes this!
Is the poster saying that it can’t meet the curve requirements? Still unable to meet the rated flow and pressure?
It’s caused by the lack of back pressure; without back pressure, the check valve cannot close properly
Agree with this view. At the same time, it is recommended to check whether the inlet filter is clogged.
Isn’t the pressure of a metering pump unrelated to its flow rate?
The outlet check valve is leaking a little; could that be the cause?
A metering pump does work by overcoming pressure; without backpressure, the pressure in the pipeline cannot be increased. There is no backpressure at the outlet, so it is easy for an excess amount of material to accumulate.
First, if the metering pump has no back pressure, the outlet pressure gauge will also show no pressure. I’m not quite sure what you mean by the fact that pressure and flow can’t be satisfied simultaneously; may I understand it this way? When you fully open the outlet valve, the flow rate increases while the pressure remains low; whereas if the outlet valve is closed tightly, the flow rate is very low even at the pump’s rated pressure. In fact, for a single test, first check whether with the valve fully open the maximum flow rate during the stroke is sufficient. Then close the valve and check that the pressure can reach the rated value.
A metering pump fills the outlet pipeline with liquid at a very slow pace. For a metering pump that has been repaired, it takes some time from startup until the outlet is filled with liquid and under pressure – this time can range from half an hour in longer cases to seven or eight minutes in shorter ones. If no pressure is detected after starting the pump, don’t assume there is a problem right away; let the pump run for a while first and then observe carefully.