Industrial Pumps Explained: Types, API 610 Standards, and How to Choose the Right One
Industrial pumps move liquids, gases, and slurries through manufacturing processes by converting mechanical energy into fluid energy. Choosing the right one depends on three factors: fluid properties, required flow and pressure, and Net Positive Suction Head (NPSH). This guide covers the main pump types, the standards that govern them, and how to select the correct pump for your application.
What Is an Industrial Pump, and How Does It Work?
An industrial pump is a mechanical device that transfers fluids by converting mechanical energy into hydraulic energy, classified primarily into two families: positive displacement and centrifugal (kinetic) pumps. Positive displacement pumps trap a fixed volume of fluid and force it through the discharge, delivering a constant flow rate regardless of system pressure. Centrifugal pumps convert rotational kinetic energy into fluid energy using a spinning impeller, making them efficient for moving large volumes over short to medium distances.
The right category depends on the application. Positive displacement pumps suit precise dosing and high-viscosity fluids, while centrifugal pumps suit high-flow, lower-viscosity applications like water transfer.
Positive Displacement Pumps: Gear, Piston, and Screw
Positive displacement pumps trap a fixed amount of fluid and displace it through the discharge, delivering consistent flow regardless of system pressure. This makes them the standard choice for applications requiring precise metering or high-pressure output.
Crude oil transport, food-grade paste and liquid handling
Handles a wide viscosity range without damaging product consistency
Positive displacement pumps for oil and gas service typically fall under API 674, 675, or 676, depending on the specific pump design, distinct from the API 610 standard that governs centrifugal pumps.
Centrifugal Pumps and the API 610 Classification System
Centrifugal pumps move fluid by converting rotational kinetic energy into hydraulic energy using a spinning impeller, making them the most common pump type for high-flow industrial applications. In petroleum, petrochemical, and natural gas service, centrifugal pumps are governed by API 610, the standard developed by the American Petroleum Institute.
API 610 classifies centrifugal pumps into three families based on mechanical configuration. OH (Overhung) pumps have the impeller cantilevered beyond the bearings and suit moderate-duty applications. BB (Between Bearings) pumps support the rotor at both ends and handle higher pressures and temperatures. VS (Vertically Suspended) pumps have the motor positioned above the fluid and excel in low-NPSH or tank applications.
For chemical process applications outside petroleum service, ANSI/ASME B73.1 is the more commonly applied standard rather than API 610. Which standard applies depends on the industry and the specific service conditions, not just the pump type itself.
What Is NPSH, and Why Does It Matter for Pump Selection?
NPSH, Net Positive Suction Head, is the pressure available at a pump's suction relative to the fluid's vapor pressure, and it's the single most important factor in preventing pump cavitation. NPSHa (available) is determined by your system's physical layout, while NPSHr (required) is determined by the pump's design.
NPSHa must always exceed NPSHr, typically with a safety margin of 1 to 2 meters or per API 610 requirements, to prevent cavitation. Insufficient NPSH causes cavitation, which damages the impeller and reduces pump life dramatically, often leading to premature failure long before a pump's rated service life is reached.
How Much Energy Do Variable Frequency Drives Actually Save?
Variable frequency drives (VFDs) on centrifugal pumps typically save more than 50 percent of energy used in low head pressure applications, and up to 60 percent in favorable conditions, according toPumps & Systems. Motor-driven pumps account for more than 30 percent of all industrial electricity consumption in the United States, making pump efficiency a meaningful lever for overall facility energy costs.
VFDs work by matching motor speed to actual system demand instead of running pumps at full speed continuously and throttling output mechanically. This also reduces motor starting current by roughly a 4:1 factor, cutting power demand spikes and reducing wear on downstream components.
How to Choose the Right Industrial Pump
The right pump matches fluid properties, required flow and head, and NPSH margin to the correct pump type and standard. Getting any one of these wrong leads to premature failure, inefficient operation, or a pump that simply can't meet the application's demands.
Start with fluid properties: viscosity, corrosiveness, and solids content determine whether a positive displacement or centrifugal design is appropriate. Next, confirm flow rate and head requirements against the pump's performance curve, and verify NPSHa exceeds NPSHr with adequate margin. Finally, confirm which standard applies, API 610 for petroleum and petrochemical service, ANSI/ASME B73.1 for chemical process applications, since standard compliance affects material certification and testing requirements.
Frequently Asked Questions
What is the difference between positive displacement and centrifugal pumps?
Positive displacement pumps trap and displace a fixed volume of fluid, delivering constant flow regardless of pressure. Centrifugal pumps use a spinning impeller to convert rotational energy into fluid energy, making them better suited for high-flow, lower-viscosity applications.
What is NPSH in pump selection?
NPSH, Net Positive Suction Head, is the suction pressure relative to fluid vapor pressure. NPSHa (available) must exceed NPSHr (required) to prevent cavitation, which damages the impeller and shortens pump life.
What standard governs centrifugal pumps in oil and gas service?
API 610 governs centrifugal pumps for petroleum, petrochemical, and natural gas applications, classifying them into OH (Overhung), BB (Between Bearings), and VS (Vertically Suspended) families based on mechanical configuration.
How much energy can a VFD save on a pump?
VFDs typically save more than 50 percent of energy in centrifugal pump applications with low head pressure, and up to 60 percent in favorable conditions, by matching motor speed to actual demand instead of running at full speed continuously.
What standard applies to chemical process pumps instead of API 610?
ANSI/ASME B73.1 is the standard more commonly applied to chemical process pumps outside petroleum and petrochemical service, where API 610's more demanding specification isn't required.
