Absolute pressure: Absolute pressure refers to the total pressure exerted on a system, encompassing both the gauge or dial pressure and the atmospheric pressure (typically considered as 14.7 psi). For instance, if a pump gauge indicates a pressure of 150 psi, the absolute pressure would amount to 164.7 psi.

Absorbed power: Absorbed power encompasses the combination of hydraulic power, which represents the work performed to achieve a specific flow rate and head, and the losses due to friction.

Acceleration: Acceleration is known as the rate at which velocity changes over time. Velocity is measured in units of distance per unit time (e.g., metres per second), while acceleration is measured as the change in velocity per unit of time (e.g., metres  per second squared).

Accelerometer: An accelerometer is a device used to measure proper acceleration, which refers to the acceleration experienced by a mass at rest within the device’s frame of reference. It does not directly measure the rate of change of velocity but rather quantifies the force or weight acting on the mass. For instance, when an accelerometer is stationary on the Earth’s surface, it will measure an acceleration of approximately 9.8 m/s² perpendicular to the surface, representing the gravitational force.

Accumulator: An accumulator is a device employed to prevent frequent cycling of a pump when taps or valves are opened within a system. Its purpose is to stabilize the pressure by offering additional water storage in conjunction with a flexible bladder that is pressurized with air. When water is drawn from the system, it is initially sourced from the accumulator tank. As the tank depletes, the pressurized bladder expands, preventing a significant drop in system pressure. Once the tank is emptied, the system pressure decreases, triggering the pump to activate and refill the tank. This cyclic process helps maintain a consistent pressure level within the system.

Acoustic: Acoustic refers to anything related to sound or the waves generated by sound.

Acoustic resonance: Acoustic resonance can occur within both closed and open pipe systems as a result of the pulsating frequency from pump excitation. It happens when the reflected pressure wave coincides with the generation of the subsequent pressure pulse, resulting in the formation of a standing wave inside the fluid-filled chamber. This phenomenon has the potential to cause severe damage or failure to systems.

Active metal: An active metal refers to a metal that has not undergone passivation, which is the formation of a thin oxide layer on the metal surface to protect it from corrosion. Prior to passivation, the metal is referred to as “active.”

Adapter: An adapter is a coupling device that connects the pump to the rest of the system, enabling seamless integration between the pump and downstream components.

Affinity laws: The affinity laws are a set of principles that establish relationships between performance variables such as impeller shaft speed, head, flow rate, and power. These laws are valuable for comparing and analyzing the performance of different pumps.

A-gap: The A-gap refers to the clearance or gap between the tips of the blades on an impeller and the inner diameter of the case bore. If the A-gap is too small, it can contribute to high pump vibration. Conversely, if the A-gap is excessively large, recirculation may occur, leading to pump inefficiency.

Air ingestion: Air ingestion happens when air leaks into the pump, causing cavitation and a degradation in pump performance. This can be attributed to issues such as leaking flanges, valves positioned above the fluid line, porous intake lines, faulty shaft seals, and other similar factors.

Alignment: In the realm of pumps, alignment pertains to the positioning of the pump shaft’s centerline in relation to the centerline of the driver shaft. This aspect is crucial since even slight misalignment on the power end can lead to significant misalignment at the wet end, where the seals are typically located.

Permissible pipe stress: This indicates the maximum allowable stresses that pipe walls can withstand, as specified by ASTM standards such as A-53 and A-106, among others. The permissible pipe stress is determined by the applicable code for a given pipe construction material and operating temperature. These factors are utilised to calculate the maximum pressure allowed according to the code.

Alpha sintered: Alpha sintered refers to one particular form of Silicon Carbide. It involves the bonding of SiC powder to create ceramics through a process called sintering. When the temperature exceeds 1700 °C, the alpha form of SiC is produced.

Ambient heat/pressure: These terms denote the environmental conditions in which the equipment operates. It could refer to either the temperature (ambient heat) or the pressure (ambient pressure) prevailing in the surrounding environment.

Angular contact ball bearing: Angular contact ball bearings are characterized by races that are displaced relative to each other along the bearing axis. This design enables the bearing to accommodate both radial and axial loads effectively.

Annealing: Annealing is a heat treatment process employed to enhance the strength of metal. It involves heating the metal to a temperature slightly below its melting point.

Anodize: Anodizing is a treatment primarily used for aluminum. This process involves applying a thick layer of protective oxide coating to the surface of the metal.

ANSI Standard: The American National Standards Institute (ANSI), established in 1918, is a non-profit organization responsible for overseeing the implementation of voluntary standards for various products. These standards specifically apply to pumps manufactured in the United States.

Anti-friction bearing: An anti-friction bearing refers to a type of bearing, either a ball or roller bearing, designed to minimize friction. This characteristic is of significant importance during maintenance activities.

Anti-rotation device: An anti-rotation device is a mechanism used to prevent one rotating component from turning in relation to an adjacent part. Typically, this device takes the form of a pin or key.

Anti-vortex plate: An anti-vortex plate serves the purpose of preventing the formation of vortices at intake suction points by increasing the path length. Vortexes can cause disruptions in vertical intakes by allowing air to enter the system along with the pumped fluid.

API gland: An API gland is a seal gland that incorporates critical safety features specified by the American Petroleum Institute (API). The primary component is a disaster bushing, which prevents sparking of metal components in the event of a bearing failure. Other elements of the API gland include a drain and vent connection, as well as a flushing connection.

API Plan 11: API Plan 11 is a specification provided by the American Petroleum Institute (API) for use in a single seal or as the primary seal of unpressurized dual seals. The purpose of mechanical seal flushing, as outlined in Plan 11, is to lubricate and cool the mechanical seal of a pump. This plan is specifically intended for pumps with impellers that have back wear rings.

API Plan 13: API Plan 13 is another specification from the American Petroleum Institute (API) used in a single seal or as the primary seal of unpressurized dual seals. Like Plan 11, the purpose of mechanical seal flushing in Plan 13 is to lubricate and cool the pump’s mechanical seal. However, Plan 13 is designed for pumps whose impellers do not have back wear rings.

API pump: An API pump refers to a pump that complies with the standards set by the American Petroleum Institute (API). These standards, such as API 610, ensure that pumps meet minimum safety, reliability, and maintainability requirements. Therefore, a pump that adheres to API standards is commonly referred to as an “API pump.”

API specifications: API specifications are recommendations provided by the American Petroleum Institute (API). These specifications outline various safety features that pumps and piping systems involved in handling flammable or hazardous substances should possess.

API 610: API 610 is a standard established by the American Petroleum Institute (API) specifically for pumps used in the petrochemical industry. This standard, known as API 610, ensures the use of safe and reliable pumps in a hazardous industry setting.

Application: The term “application” refers to the set of conditions that characterize a specific pumping operation. It encompasses the description of the process for which the pump is intended, including details about the fluid being handled and the operating conditions.

ASME: ASME stands for the American Society of Mechanical Engineers. It is an organization that promotes the advancement of multidisciplinary engineering and allied sciences on a global scale. ASME focuses on fostering the development and application of engineering knowledge and standards.

Atmospheric pressure: Atmospheric pressure refers to the pressure exerted by the Earth’s atmosphere on a given area. It is typically measured as the weight of a column of air per unit cross-sectional area. At sea level, the recognized value for atmospheric pressure is approximately 14.7 pounds per square inch (1.03 kilograms per square centimeter).

AVS Standard: The AVS Standard, which stands for American Voluntary Standard, is an outdated and obsolete standard that has been replaced by the ANSI (American National Standards Institute) standard. The AVS Standard was initially proposed in the 1950s but has since been superseded by more recent standards.

Axial flow pump: An axial flow pump is a commonly used pump type that consists of an impeller enclosed within a pipe. The impeller is driven by an electric motor or a petrol/diesel engine. The rotational movement of the propeller causes the fluid to be pumped in an axial direction along the pipe. The main advantage of this pump type is its ability to achieve a relatively high discharge flow rate while operating at a low head.

Axial split casing: An axial split casing is a type of casing used for pumps. It is constructed in two halves that are joined together, with the join running along the axis of the pump. This design allows for easier access to the pump’s internal components for maintenance and repair purposes.

Axial split pump: An axial split pump is a pump, typically in a horizontal configuration, that incorporates an axially split casing. The casing is divided into two halves, allowing for convenient access to the pump’s internal components.

Axial thrust: Axial thrust refers to the forces exerted along the axis of a pump, usually generated by the impeller. These forces can result from the hydraulic pressure created by the impeller’s rotation.

Axial thrust balancing: Axial thrust balancing involves implementing methods to counterbalance the axial forces generated by the pump impeller. Since the impeller tends to generate significant axial thrust, which it cannot move directly, the fluid is pushed instead. To mitigate this thrust, balancing drums, balancing disks, or a combination of both are employed to achieve proper axial force equilibrium.

Related Links

• Pump Glossary
• Pump info