# pump curve affinity laws

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• ### Pump Affinity Laws - Engineering ToolBox

The affinity laws are a set of forumlas that predict the impact of a change in rotational speed or impeller diameter on the head and flow produced by a pump and power demanded by a pump. If you know the shape of a pump performance curve at a certain speed or with a certain impeller diameter, you can use the affinity laws to predict the performance ...

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• ### Affinity Laws | Intro to Pumps

Pump Curve Speed Calculator. This centrifugal pump curve calculator is meant to quickly calculate the different operating conditions when a centrifugal pump is sped up or slowed down. Using affinity laws, we can accurately calculate the pressure, flow and required speed and power of a pump from a specific known set point.

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• ### Pump Curve Speed Calculator | Affinity Law Calculator

The affinity laws relate the performance of a known pump along its characteristic curve to a new performance curve when the speed is changed. This would represent the same “family” of pump curves. As an example, see Figures 5-18a–c. 1.

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• ### Affinity Law - an overview | ScienceDirect Topics

2011-12-17 · Using the classical affinity laws, the points for the new pump curve (blue) were determined by knowing the head and flow values of the original pump curve (violet) and the change in pump speed. Once you have the two pump curve plots, you can plot your system curve on top of the pumps curves to predict how the pump and system will interact.

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• ### Affinity Laws for Pumping Systems (ALPS) - Part One ...

2021-5-6 · Pump affinity laws or Pump Laws are used during hydraulic design to calculate the volume, capacity, head, or power consumption of the centrifugal pumps with changing speed or wheel diameters. These laws are very important in pump design as they express the relationship between the variables that decide the pump performance.

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• ### What Are The Pump Affinity Laws? Explanation with a

2020-4-10 · understanding of the Affinity Laws. The Affinity Laws allow Engineers to estimate the resulting changes to certain hydraulic parameters caused by the manipulation of a single centrifugal pump variable. Centrifugal Pump Fundamentals Pumps are broadly classified as kinetic or positive displacement. One of the sub-

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• ### Pump affinity laws | KSB

The affinity laws for centrifugal pumps state that the H/Q curves at various rotational speeds can be derived from the following relationship as conventionally represented:. Q Flow rate H Head Y Specific energy n Rotational speed. If P Q = ρ · g · Q · H (see Pump power output) and P = PQ η (see Pump power input), and assuming a constant density (ρ) of the fluid handled and a constant ...

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• ### Pump Affinity Laws - Crest Pumps

The pump affinity laws are a set of formulas that help predict flow, head and power absorbed at different shaft speeds. If you know the shape of a pump performance curve at a certain speed or with a certain impeller diameter, you can use the affinity laws to predict the performance of the same pump at a different speed or with a different ...

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• ### What Are The Pump Affinity Laws? Explanation with a

2021-5-6 · The Pump affinity laws are basically a set of formulas that predict the impact of Change in Pump impeller Diameter and its Rotational Speed on the Pump Head (h), Pump Flow (Q), and Power Demand of the Pump (P). Pump affinity laws or Pump Laws are used during hydraulic design to calculate the volume, capacity, head, or power consumption of the centrifugal pumps with changing speed or …

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• ### Affinity Laws - The Basis of Pump Operation

2018-9-24 · The affinity laws govern how pumps react to these changing conditions. Pumps operate in two configurations: constant speed or variable speed. A constant speed pump is driven by a motor typically supplied by the local mains electricity (or a higher voltage equivalent if it’s a really big motor and pump). ... A pump curve (in black) shows how ...

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• ### The Affinity Laws - Pump Laws - Centrifugal Pumps

2021-5-10 · The Affinity Laws – Pump Laws. The centrifugal pump is a very capable and flexible machine. It is not necessary to design specific pump for each specific system. The performance of centrifugal pump can be changed by the change in impeller diameter or its rotational speed. The affinity laws, or the pump laws, state how such changes influence the performance of the pump.

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• ### Affinity Laws - Production Technology

2017-5-1 · Thus pump performance curves for frequencies other than 60 Hz (or 50 Hz) can be generated with the affinity laws. Each curve represents a series of points derived from the 60 Hz curve for flow and corresponding head points, transformed using the Affinity Law Equations.

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• ### Centrifugal Pump Curves - CheCalc

2020-1-13 · Centrifugal Pump Curves estimate pump performance at different impellor diameter and speed based on Affinity Laws.

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• ### FURTHER EVALUATION OF THE MODIFIED AFFINITY

2021-5-15 · By utilizing the Affinity Law coefficients, the effects of pump speed and density are included in the nondimensional groups resulting in a single curve for each viscosity for all the data. The effects of viscosity are clearly evident with the head produced decreasing with increasing viscosity.

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• ### Pump Performance Curves and Similarity Laws

2007-12-7 · NPSH =36.26ft The pump will work because the system NPSH as shown in Fig. 11.7a is 30 ft which provides a 6.3 ft safety margin. Conversely, the pump could be located as close as 3.7 ft below the water surface and meet NPSH requirements. Pump Similarity Laws Application of the dimensional analysis procedures of Ch. V will yield the

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• ### Energy Tips – Pumping Systems

2014-5-22 · The affinity laws show that the pump head decreases significantly when the pump speed is reduced to match system flow requirements (see figure). Pump shaft horsepower requirements vary as the product of head and flow or as the cube of the pump’s speed ratio. Note, however, that the affinity laws will not provide accurate

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• ### Pump affinity laws | KSB

The affinity laws for centrifugal pumps state that the H/Q curves at various rotational speeds can be derived from the following relationship as conventionally represented:. Q Flow rate H Head Y Specific energy n Rotational speed. If P Q = ρ · g · Q · H (see Pump power output) and P = PQ η (see Pump power input), and assuming a constant density (ρ) of the fluid handled and a …

Get Price
• ### Pump Affinity Laws - Crest Pumps

The pump affinity laws are a set of formulas that help predict flow, head and power absorbed at different shaft speeds. If you know the shape of a pump performance curve at a certain speed or with a certain impeller diameter, you can use the affinity laws to predict the performance of the same pump at a different speed or with a different ...

Get Price
• ### What Are The Pump Affinity Laws? Explanation with a

2021-5-6 · The Pump affinity laws are basically a set of formulas that predict the impact of Change in Pump impeller Diameter and its Rotational Speed on the Pump Head (h), Pump Flow (Q), and Power Demand of the Pump (P). Pump affinity laws or Pump Laws are used during hydraulic design to calculate the volume, capacity, head, or power consumption of the …

Get Price
• ### The Affinity Laws - Pump Laws - Centrifugal Pumps

2021-5-10 · The Affinity Laws – Pump Laws. The centrifugal pump is a very capable and flexible machine. It is not necessary to design specific pump for each specific system. The performance of centrifugal pump can be changed by the change in impeller diameter or its rotational speed. The affinity laws, or the pump laws, state how such changes influence the performance of the pump.

Get Price
• ### - Affinity Laws - Beckwith & Kuffel

2021-5-16 · The affinity laws listed under 1 above will be used to determine the new performance, with N1 1750 RPM and N2 = 2000 RPM. The first step is to read the capacity, head, and horsepower at several points on the 13' dia. curve in Fig. 9 below.

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• ### Centrifugal Pump Curves - CheCalc

2020-1-13 · Centrifugal Pump Curves estimate pump performance at different impellor diameter and speed based on Affinity Laws.

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• ### 6 Centrifugal Pump Affinity Laws and Performance

Affinity Laws • The affinity laws express the mathematical relationship between several variables involved in pump performance – Q = Capacity or flow rate in gpm – H = Total Head in Feet (ft) – BHP = Brake Horsepower – N= Pump Speed, RPM – D = Diameter of the impeller • They apply to all types of centrifugal and axial flow pumps. 2

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• ### (PDF) Centrifugal Pump Head Prediction using

As with the standard affinity laws, a pump's functional relationship varies with each pump design. Yet the modified affinity laws produce a single common curve for all operating conditions and ...

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• ### Fan and Pump Curves vs. Affinity Laws - HVAC/R

2013-9-12 · The affinity laws describe the SYSTEM curve, which when placed on the published fan/pump curve determines where you device will operate. Once set you can use them to determine head at different flow, impeller diameter or speed etc.... at different conditions...

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• ### Energy Tips – Pumping Systems

2014-5-22 · The affinity laws show that the pump head decreases significantly when the pump speed is reduced to match system flow requirements (see figure). Pump shaft horsepower requirements vary as the product of head and flow or as the cube of the pump’s speed ratio. Note, however, that the affinity laws will not provide accurate

Get Price
• ### Pump Affinity Laws - Made in Britain

The pump affinity laws are a set of formulas that help predict flow, head and power absorbed at different shaft speeds. If you know the shape of a pump performance curve at a certain speed or with a certain impeller diameter, you can use the affinity laws to predict the performance of the same pump at a different speed or with a different ...

Get Price
• ### - Affinity Laws - Beckwith & Kuffel

2021-5-16 · The affinity laws listed under 1 above will be used to determine the new performance, with N1 1750 RPM and N2 = 2000 RPM. The first step is to read the capacity, head, and horsepower at several points on the 13' dia. curve in Fig. 9 below.

Get Price
• ### 6 Centrifugal Pump Affinity Laws and Performance

Affinity Laws • The affinity laws express the mathematical relationship between several variables involved in pump performance – Q = Capacity or flow rate in gpm – H = Total Head in Feet (ft) – BHP = Brake Horsepower – N= Pump Speed, RPM – D = Diameter of the impeller • They apply to all types of centrifugal and axial flow pumps. 2

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• ### Evaluating the Approximation of the Affinity Laws and ...

Affinity laws relate to the characteristics of pumps operating at different speeds, and in a water distribution context, are usually used to predict the pump curve of variable speed pumps (VSPs). VSPs can adjust the pump curve to meet the network requirements more efficiently with resultant savings of energy.

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• ### Development of Modified Affinity Law for Centrifugal

The modified affinity laws accurately models the performance dependence upon viscosity. As with the standard affinity laws, a pump's functional relationship varies with each pump design. Yet the modified affinity laws produce a single common curve for all operating conditions and viscosities for a specific pump.

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• ### Fan and Pump Curves vs. Affinity Laws - HVAC/R

2013-9-12 · The affinity laws describe the SYSTEM curve, which when placed on the published fan/pump curve determines where you device will operate. Once set you can use them to determine head at different flow, impeller diameter or speed etc.... at different conditions...

Get Price
• ### Understanding pump curves 4: variable speed – the

2013-7-15 · Affinity Laws – Modify the Pump Curve The performance of a centrifugal pump will vary with speed according to the formulae below (Fig 4). These calculations result in a set of curves called “Affinity Curves”, with imaginary lines (Affinity Lines) that pass through equivalent points on each speed curve.

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• ### Preservation of Efficiency - Affinity Revisited | Pumps ...

2006-11-6 · According to the affinity laws, the 6-in impeller should produce a BEP flow of 466-GPM at a head of 111-ft; however, as you can see, its flow is just 400- GPM @ 84-ft. The predictions are only slightly better for the 7-in impeller but come pretty close in the case of the 8-in trim because its efficiency, at 75%, is nearly that of the full size ...

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• ### Pump Performance Curves and Similarity Laws

2007-12-7 · NPSH =36.26ft The pump will work because the system NPSH as shown in Fig. 11.7a is 30 ft which provides a 6.3 ft safety margin. Conversely, the pump could be located as close as 3.7 ft below the water surface and meet NPSH requirements. Pump Similarity Laws Application of the dimensional analysis procedures of Ch. V will yield the

Get Price
• ### VARIABLE SPEED PUMPING - Energy

2017-6-2 · known as the Affinity Laws. Changing pump impeller diameter also effectively changes the duty point in a given system, and at low cost, but this can be used only for permanent adjustment to the pump curve and is not discussed further as a control method. For systems where friction loss predominates, reducing pump speed moves the

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• ### The pump affinity laws 2-1 – McNally Institute

2021-4-12 · A couple of things to keep in mind as you use the affinity laws: The affinity laws predict pump performance changes, not changes in pump system interactions. You’ll have to plot your “before and after” pump curves with your system curve to to estimate where your pump will operate. The problem is …

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• ### Affinity Laws - The Basis of Pump Operation

2021-4-20 · In the above example, this is at 462 feet of head and 1715 gpm at 82.9% efficiency. A constant speed pump only has this head curve available and will track up and down it as the system curve changes. A variable speed pump, though, has a range of potential operating points. The affinity laws tell us that the flow produced by the pump changes ...

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• ### What Are The Pump Affinity Laws? - Engineered

These equations are known as the pump affinity laws and allow for the prediction of pump performance at varying speeds. Given flow, head, and power at one speed for a specific pump, one can determine new values for those parameters at a different speed. The first pump affinity law deals with flow, or pump …

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• ### Understanding pump curves 4: variable speed – the

2013-7-15 · Affinity Laws – Modify the Pump Curve The performance of a centrifugal pump will vary with speed according to the formulae below (Fig 4). These calculations result in a set of curves called “Affinity Curves”, with imaginary lines (Affinity Lines) that pass through equivalent points on each speed curve.

Get Price
• ### (PDF) Evaluating the Approximation of the Affinity

Affinity laws relate to the characteristics of pumps operating at different speeds, and in a water distribution context, are usually used to predict the pump curve of variable speed pumps (VSPs). VSPs can adjust the pump curve to meet the network

Get Price
• ### Evaluating the Approximation of the Affinity Laws and ...

Affinity laws relate to the characteristics of pumps operating at different speeds, and in a water distribution context, are usually used to predict the pump curve of variable speed pumps (VSPs). VSPs can adjust the pump curve to meet the network requirements more efficiently with resultant savings of …

Get Price
• ### White Paper Stop Falling Off the Curve - Maintenance

2020-11-8 · the green curve. If the Affinity Laws are used Figure 2 – Pump Curve Predictions with an 18% Decrease in Impeller Diameter. to predict the head and flow, the red curve is calculated. The Affinity Laws calculate more head and flow than the 9” impeller will actually generate. In effect the Affinity Law calculated impeller will be too small.

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• ### VARIABLE SPEED PUMPING - Energy

2017-6-2 · known as the Affinity Laws. Changing pump impeller diameter also effectively changes the duty point in a given system, and at low cost, but this can be used only for permanent adjustment to the pump curve and is not discussed further as a control method. For systems where friction loss predominates, reducing pump speed moves the

Get Price
• ### Analytical Solution for Speed to Achieve a Desired ...

The Affinity Laws for fans (and pumps) provide a way of determining new fan or pump speed given fan or pump performance curve data and a desired operating point (combination of flow rate and pressure) that does not fall on the curve. However, the affinity law calculations require using a point on the curve (hereafter referred to as the “basic ...

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• ### Is Variable Speed a Magical Fix for Pumps? Part 1 of 2 ...

2021-5-8 · The affinity laws are applicable for small changes in speed, and note that the system curve still dictates where the pump will operate. Notice that a small change in speed has a big effect on power (cube function), and this is one of the main reasons why VFDs are so popular.

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