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Damage

The term "damage" refers to a change in a component that impairs or prevents its intended function ...

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Data transmission

Data transmission includes all methods that can be used to transmit information from a sender to a ...

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DC

DC is the internationally recognised abbreviation for direct current.

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Dead time

Dead time is also referred to as run time or transport time. In control systems, it designates the ...

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Declaration of Conformity

The Declaration of Conformity is a written declaration by the product manufacturer or supplier to ...

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Declaration of Incorporation

In accordance with the revised version of the Machinery Directive (2006/42/EC) dated May 2006 a ...

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Deep-well turbine pump

Deep-well turbine pump: Model with hollow shaft motor

Deep-well turbine pumps are a type of vertical shaft submersible pump. They are also known as ...

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Degree ENGLER

The degree ENGLER is an obsolete unit for quantifying viscosity.

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Degree of reaction

The degree of reaction (rth), or reaction ratio, is a parameter used for multistage turbomachinery ...

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Delta configuration

The delta configuration is a starting method whereby the three phases of a three-phase system are ...

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Density

Density (ρ) is a characteristic property for the material of a body that is independent of its shape ...

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Deposits

In contrast to surface or protective layers, deposits are unwanted effects which impinge upon the ...

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Depreciation

Depreciation is a term used to describe a loss in the value of a company's assets (specifically ...

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Design point

For the hydraulic calculation (selection) of a centrifugal pump, in general, the flow rate (Q), the ...

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Dewatering pump

Dewatering pumps are centrifugal pumps installed in a building that is situated below the groundwater ...

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Diagonal impeller

A diagonal impeller is also referred to as a helical impeller or mixed flow impeller. See Figs. 3, 4, ...

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Dielectric

A dielectric is any poorly conducting or non-conductive and non-metallic substance, in which most of ...

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Differential pressure

Differential pressure is the measured difference between two pressures, such as between the discharge ...

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Differential pressure flow meter

Differential pressure flow meters are differential pressure drop devices in which the flow is ...

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Differential pressure sensor

The differential pressure sensor is a measuring instrument (also see Sensor) that converts the ...

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Differential transformer

The differential transformer is a special type of transformer and is used in sensors. It comprises ...

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Diffuser element

Diffuser elements are hydraulically relevant components built into centrifugal pumps which alter the ...

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Diffuser vane

Diffuser vanes are stationary vanes fitted in the pump casing or diffuser. They convert velocity into ...

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Diffusor

The diffuser is a component which effects a reduction in flow velocity and corresponding increase in ...

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Digital signal

A digital signal has several information parameters (e. g. 8, 16, 32, or 64) that can be provided ...

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DIN rail

A DIN rail is part of the mounting rail group and consists of a standardised metal profile rail. It ...

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Direct current

Direct current is abbreviated internationally as DC and refers to the unidirectional flow of electric ...

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Direct current face plate starter

The direct current face plate starter is an electrical switchgear that starts direct current motors ...

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Direct current motor

The direct current motor is an electric motor that uses direct current and comprises a stator and a ...

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Direction of rotation

The direction of rotation is also referred to as the sense of rotation and indicates the direction ...

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Direct starting

Direct starting is also known as DOL starting and is a starting method for three-phase asynchronous ...

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Disc friction

Disc friction (PLdiscfric) in centrifugal pump engineering is the friction loss caused by the fluid ...

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Discharge casing

A discharge casing must be capable of withstanding a given internal and external pressure. The wall ...

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Discharge elbow

The discharge-side elbow (see Elbow) of a tubular casing pump is termed a discharge elbow.

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Discharge line

A discharge line is a section of piping where the pressure is higher than atmospheric pressure (e. g.

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Discharge nozzle

Discharge nozzle is the short name for the pump discharge nozzle.

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DN

DN (i.a.w. ISO 6708) is an alphanumeric identifier of size for components in a piping system and is ...

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Dock pump

Dock pumps are centrifugal pumps which are used for draining dock facilities. The dock pumps used ...

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DOL

DOL stands for “direct on line“ and refers to DOL starting.

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DOL starting

Direct-on-line (DOL) starting is also known as direct starting and is a starting method for ...

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Domestic water supply system

Domestic water supply systems serve to supply individual residential houses or farms with water ...

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Double-entry impeller

A double-entry impeller is an impeller with a suction entry on both sides. A double-entry impeller is ...

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Double-suction pump

In double-suction pumps the total flow rate is distributed over several impellers arranged on a pump ...

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Double volute

To balance radial thrust on volute casing pumps, a double volute is installed instead of a single volute.

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Drainage pump

Drainage pump: Submersible motor pump

The drainage pump is used for draining pits and deep roadway underpasses, as well as for dewatering ...

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Drive

Centrifugal pumps are usually driven by electric motors. Piston engines (e. g. diesel engines) and ...

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Drive rating

The drive rating is the drive power available at the shaft coupling and is measured (see Unit) in ...

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Drive starting torque

In the context of drive systems, starting torque refers to the torque that is applied to accelerate ...

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Drive systems

Drive systems convert electrical into mechanical (kinetic) energy using electrical machines and play ...

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Dry cooling

Dry cooling is a cooling process in which the coolant (water) is not in direct contact with the air ...

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Dry installation

The term dry installation is mainly used in conjunction with large vertical pumps. A dry installed ...

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Dry running

Dry running is usually undesirable in a centrifugal pump; it occurs in the total absence of the ...

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Dry running protection

Dry running protection is intended to prevent a pump from operating without fluid. For this purpose, ...

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Ductility

Ductility means the ability of a material to withstand the propagation of a crack or rupture. This is ...

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Dynamic pressure

Dynamic pressure is an abbreviated designation for hydrodynamic pressure and results from the kinetic ...

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Dynamic seal

Dynamic seals perform contact sealing between moving parts. Depending on the nature of the relative ...

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Dynamic viscosity

Dynamic viscosity (η) is defined on the basis of its unit of force as the proportionality factor ...

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