Effects of Closing the Suction Valve in a Centrifugal Pump

Proper Operation and Maintenance are critical in the operation of centrifugal pumps. One common mistake that can lead to significant issues is closing the suction valve when the pump is running. This article explores the effects of such an action and provides detailed insights into the potential hazards involved.

Loss of Flow

The immediate consequence of closing the suction valve of a running centrifugal pump is that the flow of fluid into the pump will cease. Without incoming fluid, the pump will no longer be able to perform its intended task, leading to a complete stop in the movement of water or other fluids.

Cavitation Risk

Closing the suction valve also increases the risk of cavitation. As the pump continues to operate with no fluid supply, the pressure within the pump's casing can drop below the vapor pressure of the fluid, leading to cavitation. Cavitation occurs when vapor bubbles form and collapse, creating sudden pressure changes that can cause severe damage to the impeller and other internal components. This can lead to a decrease in pump efficiency and reliability.

Increased Temperature

When the pump runs dry, the fluid inside the pump can heat up due to friction and lack of cooling, potentially leading to overheating. This overheating can cause significant damage to the pump, including warping of the impeller and other components, leading to failures and increased maintenance costs.

Pressure Increase

The pump will continue to try to maintain its designed flow and pressure, leading to an increase in pressure at the discharge side. This can cause damage to the pump itself or to any downstream equipment, potentially leading to costly repairs and downtime.

Mechanical Damage

Prolonged operation under these conditions can result in seal failure, bearing failure, or even catastrophic mechanical failure of the pump. The continuous stress and heat put on the pump can lead to serious and irreversible damage.

System Shock

If the suction valve is closed suddenly, it can create a pressure surge, commonly known as water hammer. This can cause significant damage to pipes and fittings within the system, leading to leaks and the need for urgent repairs.

Case Studies and Practical Advice

Problems with centrifugal pumps are not uncommon in various industrial settings. For instance, a sudden closure of the suction valve led to a pump burning up due to lack of liquid, causing significant downtime and expensive repairs. Similarly, closing and opening the suction valve when initially priming up a pump can help prevent such issues by allowing water to rise out of the canal or ground.

Proper operation and maintenance practices can help avoid these issues. Ensuring the suction valve is always open and the pump is adequately primed can prevent damage and ensure the pump operates efficiently. Routine inspections and regular maintenance are key to preventing unexpected failures and minimizing downtime.

Best Practices: Always keep the suction valve open. Ensure the pump is properly primed before starting. Regularly check and maintain the pump's mechanical components. Monitor pressure and temperature readings to detect potential issues early.

Closing the suction valve is highly inadvisable, as it can lead to severe operational issues and damage to both the pump and the system. By following proper procedures and maintaining the pump correctly, you can ensure a safer and more efficient operation.