# What is the relationship between HGL and EGL at a pump?

• foo9008
In summary, the conversation discussed the difference between the energy line and the hydraulic grade line of flowing fluid, with the main distinction being the presence of velocity head. Two pictures were presented, one with the two lines not joined together and the other with the lines joined together at the pump. The second picture was deemed correct as the velocity of the fluid at the pump is zero.
foo9008

## Homework Statement

the line above shows the energy line of the flowing fluid , whereas the line below shows the hydraulic geade line of flowing fluid , the diffrence between 2 lines is velocity head

## The Attempt at a Solution

i have 2 pictures here , the author drew 2 different shape of graph at the pump , in the first picture , there's some velocity head at the pump ( the 2 lines didnt joined together) , whereas in the 2nd picture , 2 lines joined together , which is correct ?

#### Attachments

• 1.PNG
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• 2.PNG
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IMO , the second picture is correct , since the velocity of fluid at pump = 0 , am i right ?

bump , which is correct ? or both are correct ?

## 1. What is a sketch of HGL and EGL at pump?

A sketch of HGL (hydraulic gradient line) and EGL (energy gradient line) at pump is a graphical representation of the hydraulic and energy conditions at a pump station in a piping system. It shows the changes in hydraulic head and energy head as the fluid flows through the pump and into the discharge pipe.

## 2. How is a sketch of HGL and EGL at pump useful?

This sketch is useful for understanding the performance of a pump station and identifying any potential issues or inefficiencies. It can also be used for troubleshooting and designing new pump systems.

## 3. What is the difference between HGL and EGL?

HGL represents the pressure head of the fluid, while EGL represents the total energy head of the fluid, including pressure, velocity, and elevation head. HGL and EGL are parallel to each other, with EGL always being above HGL.

## 4. What does the slope of HGL and EGL indicate?

The slope of HGL and EGL indicates the rate of change of hydraulic head and energy head, respectively. A steeper slope indicates a greater change in head over a given distance, which can indicate potential issues such as high friction losses or inefficient pump operation.

## 5. How can the HGL and EGL be affected by pump operation?

The HGL and EGL can be affected by pump operation in various ways, such as changes in flow rate, changes in pump speed, or changes in pump efficiency. These changes can result in shifts in the HGL and EGL curves, which can indicate changes in the hydraulic and energy conditions at the pump station.

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