The issue of no flow in small metering pumps
Thread Content
For small metering pumps used in chemical processing plants, with capacities of 200 ml/h and 100 ml/h, which manufacturers currently produce high-quality ones? We have installed 4 such pumps made by a manufacturer from the North; they often fail to deliver the required flow rate. Upon inspection, the piston diameter is around 3 mm, and no issues were found there – the problem lies in the fact that no pressure is generated at the outlet. I would appreciate it if experts could help analyze the possible causes of this issue. The inlet is properly supplied, the bypass valve is fine, and the range has also been adjusted to the maximum.
What is the outlet pressure? This flow rate is very low for metering pumps; even though it is included in some manufacturers’ product ranges, very few pumps are designed for such conditions, let alone those that are particularly suitable for it. It’s necessary to select the right pump model first, conduct thorough testing, and also pay attention to certain aspects during use. I work in the field of metering pumps, and the lowest flow rate I’ve dealt with was 0.5 L/h at 200 bar. For lower flow rates, I can’t guarantee proper performance.
You might want to look at things like electromagnetic metering pumps
Are you using a cross-flow pump? This situation is usually caused by a dirty check valve in the pump. Centrifugal pumps have high requirements regarding the cleanliness of the medium, and a filter should be installed before the pump. If the temperature, pressure, and viscosity are not high, it is also possible to check whether there is a suitable peristaltic pump available
1. Check whether the check valve is stuck； 2. Check whether the oil replenishment valve is functioning properly ； 3. Check whether the sealing ring is worn
How long does it take for no pressure to be generated after startup? How thick is the outlet pipe diameter? For the metering pump I’ve seen, it took over half an hour to start up and reach operating pressure after maintenance; the outlet pipe diameter is DN25. Your flow rate of 100 ml/h is extremely low.
Small metering pump, 200 ml/h, 100 ml/h; pay special attention to the vacuum level of the check valve. If you don’t understand, you can add me on WeChat at qdhrk2010 or 13589226713
The liquid pumping performance of such pumps is greatly affected by the turbidity of the liquid; mainly, the check valve at the outlet gets clogged, resulting in no liquid being pumped and no pressure generated.
The main reason for no measurement is the presence of debris at the inlet and outlet check valves, which prevents the formation of a sealed chamber and thus results in no measurement. If inspections are not carried out frequently, consider installing a filter at the main pipe inlet