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![]() A B C D E F G H I J K L M N O P Q R S T U V W X Y Z A Allowable operating range The range of flows or heads at the specified operating conditions of the pump supplied is limited by cavitation, heating, vibration, noise, shaft deflection and other similar criteria. This range is defined by the manufacturer. The upper and lower limits of the range are denoted by maximum or minimum continuous flow. Allowable temperature range of the pump The temperature range from minimum through maximum allowable continuous temperature for which the equipment (or any part to which the term refers) is suitable when handling the specified operating fluid at the specified operating pressure. Allowable working The limiting values and/or ranges of conditions at which the pump unit can be operated, owing to the material and the design and execution. Anti-clockwise rotation The direction of rotation in which the shaft is seen to be turning in an anti-clockwise direction, when viewing the drive-end of the shaft.
Atmospheric pressure The mean absolute pressure of the atmosphere measured at the place of installation of the pump. Auxiliary connections Connections provided for flushing, by-pass, pressure balance, or other similar purposes. Axial split Refers to casing joints that are parallel to the shaft centerline. B Balancing rate of flow The rate of flow which is extracted to activate a balance device. Barrier liquid Liquid introduced between pressurized double mechanical seals to completely isolate the pump process liquid from the environment. Basic design pressure Pressure derived from the permitted stress at 20 ° C of the material used for the pressure-containing parts. Buffer liquid Liquid used as a lubricant or buffer between unpressurized dual (tandem) mechanical seals. C Cinematic viscosity Ratio of the dynamic viscosity to the density of the pumped liquid. Clockwise rotation The direction of rotation in which the shaft is seen to be turning in a clock-wise direction when viewing the drive-end of the shaft. Close coupled A coupling arrangement in which the motor is supplied with a flange adaptor which mounts directly to the casing or body of the pump, permitting the use of a single or solidly coupled shaft. Component An assembly of parts put together to fulfil a specific identifiable function independently or in combination with other parts/components. Conditions All parameters (for example temperatures, pressures) determined by the application and the pumped liquid which affect the function and performance of the system. Corrosion allowance That portion of the wall thickness of the parts wetted by the pumped liquid in excess of the theoretical thickness required to withstand the pressure limits by the maximum allowable working pressure. Counter-clockwise rotation The direction of rotation in which the shaft is seen to be turning in an anti-clockwise direction, when viewing the drive-end of the shaft.
Coupling The link by which energy is transferred between the driver and the pump. The energy transmission may be mechanically, hydraulically or magnetically. Coupling service factor A factor which is to be multiplied by the nominal torque of the driver in order to get a fictitious torque which makes due allowance for cyclic torque fluctuations from the pump and / or its driver and therefore ensures satisfactory coupling life. Customized Pumps In the engineering industry more often optimized solutions are developed that cannot be covered with standard components. Special modifications are required for the pumps. This concerns the mounting installation, the drives and sealing systems as well as the operating conditions or standardization efforts. By means of an ingenious and proven modular construction system EDUR is in a position to supply adaptations and customized constructions in a flexible and short-term way. D Density Mass per unit volume at a stated temperature. Differential pressure The gain in total head between the pump inlet and pump outlet expressed in pressure units. Double flow Impeller with double entry flow direction. Drive Machine supplying mechanical energy. Drive power input The power absorbed by the pump drive. It is also common practice to use P1 instead of Pmot. In these cases the subscript "1" refers to the electrical input to the motor rather than to the inlet of the pump. Drive rated power output The continuous drive power output permitted under defined conditions. Duty Point The target values of the total head of the pump and the rate of flow for which a pump is designed or selected. Dynamic viscosity Ratio of the shear stress to the shear velocity acting in a liquid subjected to a plane shear motion. E F Face runout The total axial deviation indicated at the outer radial face of the shaft seal casing by a device attached to and rotated with the shaft when the shaft is rotated manually in its bearings in the horizontal position. G Gas content The proportion of gaseous substance in the liquid to be pumped either as a contaminant, or as vapour from the main body of liquid. Gauge pressure at point x The reading on a pressure measuring instrument attached to an observed point x. Guarantee point The operating performance of the pump which the supplier guarantees to be achieved under specified conditions. The guarantee point may be defined as: H Head The energy per unit mass of fluid divided by gravitation acceleration. The head may also be considered as the height of a column of fluid at rest giving a pressure onto its bottom surface equivalent to the energy per unit mass being acted upon by the acceleration due to gravity. Head at peak point The highest total head developed by a pump when this does not occur at a zero rate of flow. Hydraulic efficiency The proportion of pump power input, P, which is delivered as pump power output after satisfying the mechanical losses, losses resulting from friction due to the relative motion of internal surfaces and internal leakage. Hydrostatic test pressure The gauge pressure to which a part, component or pump is subjected for the purpose of strength or leak testing. I Industry-Bloc pump Type NUB NUBF Injection flush The introduction of an appropriate (clean, compatible etc) liquid into the seal cavity from an external source and then into the pumped liquid. Inlet area of the pump The free cross-sectional area of the entry opening in the inlet connection of the pump. Inlet pressure of the pump The pressure acting at the inlet area of the pump. Inlet rate of flow The rate of flow passing the inlet area of the pump from the inlet side of the installation. Inline-Bloc pump Type LUB Installation The arrangement of pipes, supports, foundations, controls, drives etc. into which the pump or pump unit is connected in order to achieve the service for which it was acquired. Installation (NPSHA) curve The relationship between the net positive suction head available and the rate of flow at given operating conditions and liquid. Intermediate take off rate of flow The rate of flow passing through one or more intermediate take-off points. Internal efficiency The proportion of the pump power input "P" which is delivered as pump power output after satisfying the mechanical power losses. J K L Leakage rate of flow The rate of flow leaking from shaft seals. Liquid pump A machine for the raising of liquids from a low to a high energy level for instance: Liquid-Ring Vacuum pump Type GS ZB Loss of head The difference of the head at one observed point from the head at a second observed point. M Mass rate of flow The mass of liquid discharged from the outlet area of the pump in a given time. Losses inherent to the pump i.e. discharge necessary for Maximum allowable casing working pressure The greatest outlet pressure at the specified operating temperature at which the pump casing can be used. This pressure should be equal or greater than the maximum outlet pressure. Maximum allowable continuous speed The highest speed at which the manufacturer will permit continuous operation. Maximum allowable flow Greatest rate of flow that the pump can be expected to deliver continuously without risk of internal damage when operated at the rated speed and on the liquid for which it was supplied. Maximum allowable inlet pressure The highest value of inlet pressure at which the pump or component is capable of functioning on the basis of the materials used. Maximum allowable temperature Highest allowable continuous temperature for which the equipment (or any part to which the term refers) is suitable when handling the specified operating fluid at the specified operating pressure. Maximum allowable working pressure The pressure for a component on the basis of materials used and on the basis of calculation rules at the specified operating temperature. Maximum dynamic sealing pressure The highest pressure expected at the shaft seals during any specified operating condition and during startup and shutdown. Maximum flow Greatest rate of flow which is expected at operating conditions. Maximum head The highest total head developed by a pump at any rate of flow. Maximum inlet pressure The highest inlet pressure to which the pump is subjected during operation. Maximum outlet pressure The sum of maximum inlet pressure plus maximum differential pressure derived from the furnished impeller when operating at rated conditions and density. Maximum pump power input The highest value of the pump power input at any rate of flow at any allowable operating condition. Maximum static sealing pressure The highest pressure, excluding hydrostatic testing, to which the seal can be subjected while the pump is shutdown. Mechanical efficiency The proportion of the pump power input, P, available after satisfying the mechanical power losses, P Jm at given operating conditions. Minimum allowable continuous speed The lowest speed at which the manufacturer will permit continuous operation. Minimum allowable flow Smallest rate of flow that the pump can be expected to deliver continuously without risk of internal damage when operated at the rated speed and on the liquid for which it was supplied. Minimum allowable stable flow The lowest flow at which the pump can operate without exceeding the noise and vibration limits imposed in the order. Minimum allowable thermal flow The lowest flow at which the pump can operate without its operation being impaired by the temperature rise of the pumped liquid. Minimum continuous stable flow The lowest flow at which the pump can be operated without it adversely affecting its performance in terms of life expectancy, noise and vibrations. . Minimum continuous thermal flow The lowest flow at which the pump can operate without its operation being impaired by the temperature rise of the pumped liquid. Minimum flow Smallest rate of flow which is expected at operating conditions. Mixture A combination of one or more substances remaining separate yet behaving as a single liquid for pumping. Motor efficiency The proportion of the drive rated power output, P mot u delivered as pump power input, P mot. Multiphase A mixture comprising a liquid together with substances in solid, or gaseous states whether due to deliberate addition or change of state due to changed conditions. Multiphase pumps Type PBU EB LBU Multistage A pump with more than one impeller mounted on the same shaft and connected so as to act in series. Multistage pumps Type LBU VBU NU NHP Z N Net positive suction head 3% The NPSH required to limit to 3% the fall in the total head of the first stage of the pump. Nominal An appropriate rounded value of a magnitude to designate a component, a unit or a device. Normal flow Rate of flow at which usual operation is expected. NPSH = Net positive suction head The margin of the absolute value of the static head above the head equivalent to the vapour pressure of the liquid at the particular temperature, referred to the NPSH-datum plane. NPSHA = Net positive suction head available The minimum (NPSH) available at the inlet area of the pump as determined by the conditions of the installation for a specified rate of flow. NPSHR = Net positive suction head required The minimum (NPSH) at the pump inlet connection required to give rated or operating performance at the specified conditions. The minimum value may be determined by one of a number of different criteria such as visible cavitation, increase of noise and vibration (due to cavitation), defined head or efficiency drop or limitation of cavitation corrosion. O Operating conditions All parameters (for example operating temperature or pressure) determined by a given application and pumped liquid. Operating point The point at which a pump will operate in an installation. It will occur at the intersection of the pump H-Q-curve and the installation HA-Q-curve. Optimum head The total head developed by the pump at a rate of flow corresponding to the best efficiency. Optimum pump power input The pump power input at the rate of flow corresponding to the best efficiency. Optimum rate of flow Rate of flow at the point of best efficiency. Outlet area of the pump The free cross-sectional area of the orifice in the outlet connection of the pump. Outlet pressure of the pump The pressure acting at the outlet area of the pump. Outlet rate of flow The rate of flow passing the outlet area of the pump from the outlet side of the installation. Overall efficiency The proportion of the driver power input, Pmot delivered as pump power output, Pu. P Parallel operation Pumps operating with inlet connections interconnected and outlet connections interconnected to permit simultaneous operation in the same system giving increased rate of flow. Part A piece of equipment which when assembled together with others makes a pump. Peak point The point of highest achieved total head in an unstable pump H-Q-curve. Pressure at point x The force per unit area exerted at the observed point x. Pressure casing A composite of all stationary pressure containing parts of the unit, including all connections and other attached parts but excluding the stationary and rotating / oscillating parts of shaft / rod seals. Pressure head The head corresponding to the pressure shown on a manometer at an observed point indicated by the subscript. Pressure-temperature rating Pressure-temperature limit of a component at given design and material. Product lubrication An arrangement in which the bearings are submerged in and lubricated by the pumped liquid. Pump In general pumps are defined as being terminated by their inlet and outlet connections as well as in general their shaft ends. Pump (NPSHR) curve The relationship between the net positive suction head required and the rate of flow at given operating conditions of speed and liquid. Pump best efficiency The greatest value of pump efficiency obtained at a given speed pumping a given liquid. Pump efficiency The proportion of the pump power input, P, delivered as pump power output, Pu, at given operating conditions. Pump efficiency curve The relationship between the pump efficiency and the rate of flow at given operating conditions of speed and liquid. Pump mechanical power losses The power absorbed by friction in bearings and shaft seal at given operating conditions of the pump. Pump power input The power transmitted to the pump by its drive. Pump power input curve The relationship between the pump power input and the rate of flow at given operating conditions of speed and liquid. Pump power output The useful mechanical power transferred to the liquid during its passage through the pump. Pump rated power input The power required by the pump at the rated conditions. Pump unit A pump unit comprises the pump, the drive including transmission elements, baseplate and any auxiliary equipment. Pump-H-Q-curve = characteristic curve = pump head capacity curve The relationship between the total head of the pump and the rate of flow at given operating / rated conditions of speed and liquid. Pumped liquid The liquid or fluid which will be handled by the pump at specified operating conditions. Q Quenching Continuous or intermitted introduction of an appropriate (clean, compatible etc) fluid on the atmospheric side of the main shaft seal. Used to exclude air or moisture, to prevent or clean deposits (including ice), lubricate an auxiliary seal, snuff out fire, dilute, heat or cool leakage. R Radial split Refers to casing joints that are transverse to the shaft centerline. Rate of flow The volume rate of flow corresponding to the mass rate of flow given by the equation: Q = q/ ρ. Rated A specified performance selected to ensure that the operating performance will be achieved by the pump or pump unit when installed. Rated conditions Conditions (drive excluded) that define the guarantee values necessary to meet all defined operating conditions, taking into account any necessary margins. Rated differential pressure The differential pressure for the operating conditions at the guarantee point. Rated flow Rate of flow at the guarantee point taking into account any necessary margin. Rated inlet pressure The inlet pressure of the operating conditions at the guarantee point. Rated outlet pressure The outlet pressure of the pump at the guarantee point with rated flow, rated speed, rated inlet pressure and density. Rated speed The number of rotation per unit of time of the pump required to meet the rated conditions. Rotodynamic pump A machine to transfer mechanical energy through a rotating impeller to gain velocity and pressure for the pumped liquid. Rotor The assembly of all rotating parts of a rotodynamic pump. S Seal flushing (circulation) The return of pumped liquid from high pressure area to seal cavity. It can be by external piping or internal passage and is used to remove heat generated at the seal or to maintain positive pressure in the seal cavity or treated to improve the working environment for the seal. In some cases it may be desirable to circulate from the seal cavity to a lower pressure area. Sealing liquid Liquid introduced between pressurized double mechanical seals to completely isolate the pump process liquid from the environment. Sealing liquid Liquid used as a lubricant or buffer between unpressurized dual (tandem) mechanical seals. Selfpriming pumps Type E S SUB Series operation Pumps operating with the outlet connection of the first connected to the inlet connection of the next pump to permit simultaneous operation in the same system giving higher outlet pressure. Shaft runout The total radial deviation indicated by a device measuring shaft position in relation to the bearing housing as the shaft is rotated manually in its bearings with the shaft in the horizontal position. Shaft stiffness A comparative expression describing the ability of shafts to resist bending loads. Shut-off head The total head developed by the pump in a zero rate of flow. Shut-off pump power input The pump power input at zero rate of flow. Single flow Impeller with single entry flow direction. Single stage A pump with one impeller only. Solid content The proportion of solids contained in the liquid to be pumped either as a contaminant or as a deliberate useful burden or suspension.
Specific speed The speed which characterises a pump in terms of its speed, flow rate per impeller eye, i.e. total flow for single flow impeller, one half flow for double flow impeller at best efficiency point and head per stage at maximum impeller diameter. Speed The number of rotations or movements made by the shaft, coupling or impeller in unit time. Stable pump H-Q-curve A pump H-Q-curve where the maximum head and shut-off head are coincidental and the total head declines continuously with increasing rate of flow. Stainless-Bloc pumps Type CB BC Standard DIN EN 733 pumps Type N Standby pumps Pumps additional to the duty need installed to provide immediate cover in the event of failure of the main pumps. Static head That portion of total head at an observed point in an installation which is independent of rate of flow. Sub-assembly An assembly of parts put together for convenience which may or may not fulfil a discrete function. Submersible pump A pump unit designed to operate fully submerged in the pumped liquid. System Those parts of an installation which together with the pump determine the functional performance of the installation. T Test Terms which describe the characteristics of the pump or the fluid or the conditions which exist during an examination. Throttle bush Close-clearance restrictive bushing around the shaft (or sleeve) at the outboard end of a mechanical seal, to reduce leakage in case of seal failure. Torque-Flow-Bloc pumps Type FUB CBF Total differential head of the pump unit The difference of the total head at the outlet side of the pump unit from the total head at the inlet side of the pump unit. Total head The head at an observed point corresponding to the sum of the height, pressure head and the velocity head of the fluid at that observed point. Trip speed The speed at which the independent emergency overspeed devices operate to shut down a prime mover. U Unstable pump H-Q-curve A pump H-Q-curve where the maximum head (peak point) and shut off head are not coincidental or the total head does not decline continuously with increasing rate of flow. |
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