When we think of fluid dynamics and pump engineering, the concept of Net Positive Suction Head (NPSH) is something that a lot of folks don’t understand. It is a measure of the pressure available at the pump suction to prevent cavitation. Cavitation can cause significant damage to pump components. When it comes to MTH Pumps’ regenerative turbine pumps, their low NPSH properties are very unique and one of the lowest in the world of rotodynamic pumps, providing several operational advantages.
What is NPSH?
NPSH is divided into two types:
- NPSH Available (NPSHa): The absolute pressure at the suction port of the pump.
- NPSH Required (NPSHr): The minimum pressure required at the suction port to prevent cavitation.
For a pump to function without cavitation, NPSHa must be greater than NPSHr.
Regenerative Turbine Pumps: A Brief Overview
Regenerative turbine pumps, also known as peripheral pumps, are designed to handle low flow, high head applications. Unlike centrifugal pumps, which impart velocity to the fluid primarily in one direction, regenerative turbine pumps create a regenerative action. Fluid is recirculated multiple times through the impeller vanes, building pressure incrementally.
Low NPSH Properties of MTH Pumps Regenerative Turbine Pumps
MTH Pumps has engineered their regenerative turbine pumps to exhibit exceptionally low NPSH requirements. Here’s why this is crucial:
- Reduced Risk of Cavitation: Low NPSHr values mean that these pumps can operate efficiently with lower suction pressure. This is particularly beneficial in applications where maintaining high suction pressure is challenging. The reduced risk of cavitation not only extends the life of the pump but also ensures consistent performance.
- Enhanced Operational Flexibility: Pumps with low NPSH properties can handle fluids in conditions where traditional pumps might fail. This makes MTH regenerative turbine pumps ideal for handling volatile liquids or fluids near their boiling point. Industries such as chemical processing, pharmaceuticals, and refrigeration benefit significantly from this capability.
- Improved Suction Performance: The design of MTH Pumps’ regenerative turbine pumps allows them to handle higher vapor pressures, meaning they can draw fluids from greater depths or from storage tanks with lower liquid levels. This improved suction performance translates to greater reliability in various operational scenarios.
Key Design Features
Several design elements contribute to the low NPSH properties of MTH Pumps regenerative turbine pumps:
- Advanced Impeller Design: The impellers are designed to facilitate the regenerative process efficiently, ensuring that fluid recirculates and pressure builds gradually.
- Precision Engineering: Tight manufacturing tolerances and high-quality materials reduce internal losses and improve the overall efficiency of the pump.
- Optimized Flow Paths: Streamlined internal flow paths minimize turbulence and ensure smooth fluid movement, contributing to lower NPSHr.
Close couple T31, T41, and T51 Series pumps maintain low NPSH (Net Positive Suction Head) while operating under normal ambient temperatures. This is because of their small diameter impellers, along with tight fluid cavities while the fluid is being worked to ensure that the formation of vapor is pushed out of the pump before it can cause any damage. When the NPSH becomes too much for regenerative turbine pump to handle like when temperatures rise, the performance of the pump decreases, but the pump remains operational, and will resume normal head-capacity when the fluid cools down.
For the larger flex coupled pumps, MTH has developed proprietary inlet and pumping techniques for reducing the NPSH required by its pumps to handle hot fluids near their boiling point with minimal cavitation. When pumping water at or near 212 degrees F it becomes more and more difficult to draw the fluid into the pump inlet without vaporizing it and causing vapor lock. Even if there is some cavitation in the pump, Regenerative Turbines are well known for having some of the best resistance to cavitation erosion and can often handle vapor in excess of 20% for certain periods of time. Most of our flex coupled pumping products will handle 4 foot NPSHA, but our 250/260/270 Series can handle down to 2 feet, with some of our 240/280 Series capable down to 1 foot. Please see our Standard Products for more info.
Applications and Advantages
MTH Pumps regenerative turbine pumps are widely used across various industries due to their low NPSH properties. Some of the key applications include:
- Chemical Processing: Handling corrosive or volatile chemicals with precision and safety.
- HVAC Systems: Efficiently moving refrigerants in heating, ventilation, and air conditioning systems.
- Industrial Manufacturing: Providing reliable fluid transfer in processes where maintaining high suction pressure is challenging.
The advantages these pumps bring to such applications include:
- Operational Efficiency: Lower energy consumption due to efficient fluid handling.
- Durability: Extended lifespan of pump components owing to reduced cavitation risk.
- Versatility: Ability to handle a wide range of fluids and operating conditions.
The low NPSH properties of MTH Pumps regenerative turbine pumps are second to none. Their ability to operate efficiently under low suction pressure conditions makes them an invaluable asset in various industrial applications. By reducing the risk of cavitation and enhancing operational flexibility, these pumps ensure reliable and efficient fluid transfer.
Understanding these properties allows engineers and operators to make informed decisions, ensuring optimal performance and longevity of their pumping systems. Whether in chemical processing, HVAC, or industrial manufacturing, MTH Pumps’ regenerative turbine pumps provide a solution that meets the demands of challenging fluid handling scenarios.
MTH Pumps is a “Made-in-the-USA” manufacturer since 1965, that specializes in high pressure, low flow regenerative turbine pumps. Our Pumps produce as little as 5 PSI up to 1,000 PSI and anywhere from a ½ gallon to 150 gallons per minute. They are available in rugged, cast construction iron, bronze, and stainless-steel materials with a variety of sealing options. We have both horizontal and vertical models with a number of drive options including AC / DC volt motors or pedestal mountings. Every pump is 100% tested before it leaves our facility. MTH is an ISO certified company in a state-of-the-art, quality driven factory in Plano, Illinois. Please see our products we offer at www.mthpumps.com or call us, 630-552-4115.
