Pump evacuation poses great hazards! Identify the cause to avoid equipment damage

Analysis of pump evacuation operating conditions

1. Core phenomenon of water pump evacuation

Insufficient water intake into the pump chamber, mixed with a large amount of air, intermittent water discharge, fluctuating pressure, abnormal vibration and noise, sharp decrease in flow rate, and in severe cases, water cut-off may occur.

II. Common reasons for downtime

(1) Issues on the inlet side

1. Liquid level too low: The water level in the pool or tank is below the suction port, causing the liquid surface vortex to entrain air

2. Air leakage in suction pipe: Air ingress due to damage of flange, gasket, packing, or pipeline

3. Suction lift does not meet the standard: The actual suction height exceeds the allowable vacuum suction height range of the pump

4. Blockage of inlet filter screen: Impurities block the filter screen, causing the inlet flow rate to fail to match the outlet speed

(2) Pipeline and operation issues

1. The inlet valve is not fully opened, resulting in half-closed throttle and relatively high water intake resistance

2. The gas trapped in the pipeline has not been fully discharged, and there is air inside the pipeline before starting the machine

3. Parallel water pumps compete for water, and pumping by a single device can easily cause negative pressure and suction on the inlet of the other device

(3) Pump body and operating condition issues

1. The impeller is worn and the sealing components are damaged, resulting in a decrease in water intake efficiency

2. High-lift pump with small flow rate holds pressure and instantly opens the outlet valve wide

3. The medium temperature is relatively high, causing the liquid to vaporize and generate gas

III. Related hazards brought by smoking

1. Severe vibration noise

The gas-liquid impact on the pump body and impeller causes significant overall vibration of the equipment, leading to potential loosening and cracking of pipeline flanges and supports.

2. Cavitation damage to the impeller pump casing

When bubbles burst at high speed and impact the metal surface, pitting, holes, and thinning or even fracture of components occur on the impeller surface, resulting in a decrease in the operating efficiency of the water pump.

3. Motor overload damage

Under conditions of idling and gas-liquid mixing, the load is unstable, the current fluctuates greatly, and tripping is prone to occur, potentially damaging the motor coil.

4. Accelerated damage and leakage of sealing components

In the absence of liquid lubrication and cooling under vacuum conditions, the mechanical seal undergoes dry grinding and heating, gradually leading to water seepage and leakage.

5. Interruption of production water supply operation

Instability in water discharge and interruptions in water flow affect the normal operation of water supply, material conveying, and equipment cooling systems.

6. Water hammer impact in pipelines

Repeated changes in airflow and water pressure impact valves and elbow components, reducing the lifespan of pipeline fittings.

IV. On-site rapid troubleshooting solutions

1. Raise the inlet water level to reduce the formation of liquid surface vortices, and install anti-vortex plates at key locations

2. Check the air leakage position in the suction pipeline, tighten the flange components, and replace the aged and damaged gaskets

3. Before starting the machine, completely remove the accumulated air inside the pump body and pipeline

4. Clean the debris attached to the water inlet filter screen, and keep the water inlet valve fully open during operation

5. Reduce the suction height and ensure that the operating parameters are within the rated suction range of the pump

6. If the phenomenon of air entrainment occurs frequently, a vacuum gauge and a liquid level interlock device can be installed to trigger a shutdown protection when the water level is low

7. For applications with significant fluctuations in operating conditions, variable frequency equipment can be used to facilitate smooth start-up and shutdown, reducing the occurrence of pump-off phenomena

V. Key points of daily prevention

- Avoid operating the equipment for extended periods at low water levels

- Regularly check the water inlet sealing structure and the status of the filter screen

- Start and stop the exhaust according to the standardized process to reduce frequent and large-scale valve opening and closing operations

- For water pumps with a relatively high suction lift value, the installation height should be appropriately lowered