Stable inlet pressure is the key to avoiding cavitation and ensuring the life of the impeller of the fluoroplastic magnetic pump. It can be comprehensively judged through tool monitoring, data analysis, and phenomenon observation. At the same time, the corresponding solutions must be mastered.

一、Real-time monitoring with professional tools

1.Install a pressure gauge: Install a corrosion-resistant pressure gauge (e.g., stainless steel, with an accuracy of ≥1.6) on the pump inlet line (1-2 pipe diameters from the pump body) to visually read the pressure. Under normal operating conditions, the pressure should be stable within ±5% of the rated inlet pressure of the equipment. If the pointer swings frequently (the amplitude exceeds ±0.05MPa) or drifts continuously, it means that the pressure is unstable.

2.Use a pressure transmitter: For scenarios requiring continuous monitoring, install a pressure transmitter and connect it to a control system to record the pressure curve in real time. If the curve shows irregular fluctuations, sudden rises and falls (e.g., fluctuations exceeding 10% of the rated value within 1 minute), or prolonged deviations from the set range (over 30 minutes), it indicates unstable pressure.

二、Analyze the correlation between pressure data and working conditions

1.Compare the design parameters: Compare the actual monitored pressure with the "rated inlet pressure" marked in the pump manual. If the actual pressure is lower than the minimum allowable inlet pressure for a long time (for example, the minimum inlet pressure of ordinary fluoroplastic magnetic pumps is mostly 0.02MPa), or frequently fluctuates outside the "minimum - maximum" range, be alert to pressure abnormalities.

2.Observe the linkage changes in flow: There is a positive correlation between inlet pressure and flow. If the flow meter shows that the flow rate fluctuates (fluctuations exceed ±10%) and is accompanied by synchronous changes in the inlet pressure, it is likely that the inlet pressure is unstable (for example, the inlet pipe is blocked, causing the pressure to drop and the flow to decrease accordingly).

三、Assisted judgment through pump operation phenomenon

1.Listen to the operating sound: During normal operation, the pump body makes a uniform "buzzing" sound. If there is a "hissing" cavitation sound, a "clicking" abnormal sound, or the sound is sometimes loud and sometimes soft, it may be that the inlet pressure is unstable, causing medium vaporization (cavitation) or flow fluctuations. Further confirmation is required in combination with pressure data.

2.Check vibration and temperature: Unstable inlet pressure can easily lead to increased pump vibration (amplitude exceeding 0.08mm) or abnormally high pump casing temperature (over 80°C). You can feel whether the vibration is uniform by touching the pump body, or use a thermometer to monitor the temperature. If the vibration, temperature and pressure fluctuations occur simultaneously, it can be determined that the inlet pressure is unstable.

四、Solution to unstable inlet pressure

1.Regarding the fluctuation of the inlet tank liquid level: If the pressure changes due to the fluctuating high and low liquid level in the tank, it is necessary to install a liquid level control system (such as a float level valve, a liquid level transmitter linked to the feed valve) to keep the tank liquid level within the set range (it is recommended that the liquid level be at least 1.5 meters higher than the pump inlet to avoid insufficient siphoning); if the tank is intermittently fed, a buffer tank can be added to balance the inlet medium pressure.

2.For inlet pipe blockage/leakage: Check the inlet pipe regularly (once a month). If the filter is found to be clogged (judged by a drop in the pressure gauge reading, such as a pressure drop of more than 20% compared to the initial value), the pump must be stopped and the filter must be disassembled to clean out impurities (filtration accuracy ≤ 0.1mm to prevent particles from entering the pump body). If the pipe interface leaks, replace the corrosion-resistant sealing gasket (such as a polytetrafluoroethylene gasket) and tighten the bolts evenly to prevent pressure fluctuations caused by air inhalation.

3.For abnormal feed pump pressure supply: If the inlet pressure depends on the feed pump, it is necessary to check the operating status of the feed pump. If the feed pump pressure fluctuates, adjust the outlet valve opening or replace the pressure-stabilizing feed pump. If the feed pump flow is insufficient, a spare feed pump can be connected in parallel to ensure a continuous and stable supply of the inlet medium.

4.Regarding pressure fluctuations caused by cavitation: If cavitation is caused by too low inlet pressure, the inlet tank height can be raised (increase static pressure), or a booster pump can be installed in the inlet pipeline (increase pressure to above the minimum allowable inlet pressure); at the same time, the inlet pipeline length can be shortened, the number of elbows can be reduced, and the flow resistance of the medium can be reduced to avoid repeated cavitation.

By using the above judgment method to promptly identify inlet pressure problems and take targeted solutions, it is possible to effectively avoid cavitation, impeller wear and other failures caused by unstable pressure in fluoroplastic magnetic pumps and extend the service life of the equipment.