Thermal Spray for Pump Cavitation
Since the invention of the modern centrifugal pump in the 17th century, man has been fighting and fearing cavitation. Cavitation is the formation of tiny vapor bubbles in a liquid due to low pressure pockets. Think of it like the bubbles in boiling water but instead of heat forming the bubbles, it is caused by a difference in pressure from fluid moving through the pump. This phenomena can happen in any type of liquid. When these bubbles form and then explode in the confined spaces of a pump it causes significant damage.
Can We Prevent It Altogether?
The best way to prevent cavitation is to operate pumps at their designed flow rate and to be mindful of the manufacturer's pump curve. Since this is not always possible, you can also ensure that the pump is made of a material that can better withstand cavitation damage. Purchasing a pump made of these materials is very expensive though. One solution is to select an economically priced pump and use thermal spray to protect the surfaces within the pump that might see cavitation damage with premium quality materials.
The Engineered Solution
Better Protection than Ever BeforeThermal spray is a coating process like spray painting, but with molten metal. A desired coating material is heated and applied using air and gases to the pump impeller, casings and other high-wear areas. Thermal spray can be applied on a new pump to prevent corrosion, material erosion and cavitation damage or it can be combined with machining and welding services to repair components that have been previously damaged in operation. Thermal spray can be used to repair many different pump components.
In the past, thermal spray coatings have certainly been hard enough to withstand cavitation but not always ductile enough. The standard coatings would provide some protection against cavitation but would break apart quickly during prolonged exposure. High Velocity Air Fuel (HVAF) is a specialized type of thermal spray that allows for coating materials to be sprayed near their melting points creating a more uniform and ductile coating. HVAF coating offers more cavitation protection over its other high velocity predecessor, HVOF. We discuss the differences and benefits of HVAF over HVOF over on our other blog post, HVAF: A New Way to Thermal Spray. HVAF is an economical, quality solution to extend the life of pumps.
Cavitation will always be a formidable enemy to the lifespan of a pump, but it does not have to be the end. It is like dropping your smartphone. It is probably going to happen at some point. So you put a phone case on it to extend its life and protect it from fatal damage. Thermal spray coating a pump's components can give you the peace of mind that if cavitation happens, your pump will be able to withstand more.