Installation of metering pumps and piping installation considerationsFirst, to prevent the pipe from vibrating fluid inertial resistance
exhaust side, pump start moment, will have a ripple impact on pipeline. This is the unique phenomenon of reciprocating pumps, is due to the liquid in the pipe are caused by sudden acceleration. In order to combat this phenomenon, we request the discharge end inertial resistance (Pid) <1.0kgf/cm2 when Pid 1.0kgf/cm2 is reached, the pipeline will cause vibrations, will adversely affect the pump and its peripherals.
Solution: 1. install pulse dampers; 2. the increased diameter of the outlet pipe and shorten the length of the export pipeline.
excess supply, preventing excessive supply was due to the inertia of liquid flow in the pipeline, work affecting the check valve, the check valve failed, causing the flow rate of the pump is too large and unstable. When insufficient negative pressure suction side or pipe passing through long, are likely to produce this phenomenon. Therefore, we demand: measuring the differential pressure of the pump > inertial resistance to Pi (inlet port or outlet port is greater).
Solution: 1. install pulse dampers; 2. install back-pressure valve; 3. minimize the length of import and export pipelines;
third, preventing cavitation
If the unit loses (NPSHa) lack of metering pump may stop or cavitation damage. Therefore, we request the device loses, NPSHa> cavitation allowance required (NPSHr), NPSHa=Pa-Pv ± Phs-Pis* (* select larger or Pfs).
Pa: absolute pressure kg/cm2Pv of the liquid: liquid vapor pressure kg/cm2Phs: into the water height (height is level with the surface) the relative pressure (kg/cm2 into absorption taking "+" absorption absorption take on "-" Pis: into the water kg/cm2Pfs inertial resistance: into the water pipe resistance kg/cm2