Centrifugal pumps are essential in a range of applications as they effectively transfer fluids between different locations with precision and efficiency. However, cavitation poses a significant risk to their functionality by causing damage that is often expensive to repair and results in downtime. This blog will delve into the topic of cavitation.
What is Cavitation in Centrifugal Pumps?
Imagine when liquid inside a container turns into bubbles due to a decrease in pressure. That’s what cavitation is about! It’s like watching water boil and transform into steam bubbles as it gets hotter and hotter in a pot or when a centrifugal pump creates vapor bubbles by reducing pressure at the impeller’s eye.
As these air pockets move through the pump and encounter regions of increased pressure, they crush suddenly. This crushing action creates shock waves and tiny jets within the liquid. It can lead to issues for your centrifugal pump.
What Causes Cavitation in Centrifugal Pumps?
Knowing the reasons is crucial for avoiding cavitation. There are a few causes below.
Insufficient Net Positive Suction Head Available (NPSHa)
The Net Positive Suction Head Available (NPSHa) represents the pressure disparity at the pump inlet compared to the vapor pressure while factoring in elevation changes and frictional losses. A deficiency signals that the pump is not getting pressure to avoid liquid vaporization at the impeller entry point.
High Liquid Velocity
When the liquid rushes through the pump swiftly, it may cause pockets of reduced pressure. These pressure decreases could result in cavitation in spots where the flow passage constricts.
Inadequate Pump Design
The way the pump is constructed can have an impact on cavitation occurrence. Sharp corners or sudden shifts in flow direction and inadequate spaces between parts may lead to turbulence and decrease pressure efficiency in the pump which can cause cavitation issues.
Operating at Off-Design Points
In every pump lies a point of efficiency known as the BEP—this is where it functions most effectively at a particular flow rate and head pressure level. Using the pump outside its BEP range can cause flow behaviors and varying pressure levels that may result in cavitation issues.
Elevated Liquid Temperature
When the temperature of a liquid goes up, the pressure of its vapor also increases, making it easier for the liquid to turn into vapor at pressures and raising the likelihood of cavitation. In situations with temperatures, it’s essential to assess NPSHa and the operating conditions to avoid any potential issues.
Viscosity and Gas Content of the Fluid
The thickness and amount of gas in the liquid also affect cavitation occurrence, where liquids with viscosity and abundant dissolved gas are more prone to cavitation due to their lower resistance to pressure changes, making them vaporize more readily.
Effects of Cavitation on Centrifugal Pumps
Experiencing cavitation can lead to consequences for your centrifugal pump and may ultimately affect its efficiency and longevity.
Reduced Pump Performance Issue
Cavitation causes disturbances in the flow which leads to a decrease, in the pump efficiency. The formation of bubbles and shock waves results, in turbulence that impacts the capacity of the pump to transfer energy efficiently.
Lowered Flow Rates
It occurs when vapor bubbles form and collapse in the flow path of the pump limiting the amount of liquid it can effectively manage.
Vibration and Sound Issues
When vapor bubbles collapse inside the pump system, it creates shock waves that result in vibrations and noisy operation.
Erosive wear and pitting
In pumps, as the implosion of vapor bubbles generates liquid streams that gradually wear down the pump components by forming pits on the impeller and casing surfaces over time.
Decreased Pump Longevity
The combined impacts of erosion pitting and heightened mechanical strain hasten the deterioration of pump parts resulting in a reduced lifespan and early malfunction.
How Can Cavitation Be Prevented?
Luckily some approaches can effectively reduce or stop cavitation in pumps;
Pump Selection and Design Considerations
Choose pumps that have impellers crafted to reduce turbulence and pressure variations effectively by having profiles and adequate clearances to avoid cavitation issues.
Choosing highly resistant materials to erosion and corrosion can enhance the durability of your pump against the impacts of cavitation.
Be cautious of using a pump that’s excessively big for the task, as it may cause the pump to run below its optimal efficiency point (BEP), thus heightening the likelihood of cavitation issues occurring select a pump that suits the required flow rate and head appropriately.
Optimal Operating Conditions
Managing settings is vital in reducing the chances of cavitation occurring.
Make sure that the Net Positive Suction Head Available (NPSHa) is always higher than the required NPSHa of the pump by keeping a good suction head and reducing pressure losses in the suction line.
Ensure to regulate the flow rates to prevent speeds that may cause cavitation.
Use the pump within its intended limits to avoid any disruptions in flow and changes in pressure.
Regular Pump Maintenance
Regular maintenance procedures can assist in detecting and resolving cavitation concerns before they escalate.
Check the impeller regularly for any indications of wear and tear or damage to address any problems away.
Make sure to inspect for any air leaks in the suction line, as they can bring air into the system and raise the chances of cavitation occurring.
Keep an eye on the vibration levels. Check for any rises in vibrations as they could signal cavitation or other mechanical issues.
Check the seals and gaskets to make sure they are in shape so that air doesn’t get in. The system pressure stays stable.
Remember to apply lubrication to bearings and other moving components to minimize friction and enhance the efficiency of the pump while also preventing wear and tear.
Advanced Technologies and Innovations
Cutting-edge advancements and new solutions are being developed to address cavitation with efficiency.
Variable Speed Drives (also known as VSD) offer control over the pump speed to adjust to operational scenarios and reduce the likelihood of cavitation issues.
Coating impeller surfaces with treatments can help them withstand erosion better and prolong their lifespan in environments of cavitation.
Having pump operators with training is essential for identifying and averting cavitation issues effectively. Operators who grasp the causes of cavitation can proactively take measures to avoid it.
Yantai Longgang Pump Industry: A Reliable Centrifugal Pump Supplier
Longgang Pump Industry in Yantai focuses on designing and manufacturing pumps for a range of industrial uses. They are known for being a choice when it comes to fulfilling your pump requirements.
Expertise and Experience
The Yantai Longgang Pump Industry has a wealth of experience providing pumps, for industries like petroleum and petrochemicals well as coal chemical and environmental protection sectors along, with water treatment solutions. They have established themselves as a trusted supplier to leading corporations showcasing their dependability and proficiency in the field.
Research and Development Capabilities
Yantai Longgang Pump Industry has a dedicated R&D team and actively collaborates with universities to drive innovation in their products.1112 They utilize advanced design and simulation tools, such as CFD, to ensure high efficiency and performance.
Quality and Service Commitment
At Yantai Longgang Pump Industries core values are centered around ensuring top-notch product quality and exceptional customer service is a priority. They have successfully acquired certifications such, as ISO9001 and API certification to showcase their dedication to upholding high-quality standards. Moreover, they provide a range of after-sales services, including assistance, spare parts availability, and periodic follow-up visits to guarantee customer contentment.
