How does pipe diameter affect pressure in fluid flow?

In summary, changing the diameter of a pipe can affect pressure by decreasing it and increasing velocity. The rate of pressure decrease is dependent on velocity and can be calculated using minor loss coefficients. Pressure change may be negligible if starting velocity is low.
  • #1
DinjiP
7
0
How does change in pipe diameter affect pressure? For example, ethylene in a 6" pipe at 400 psi, enters a 1" pipe. How does the pressure change?

I am fairly sure that pressure decreases and velocity increases. However, I need to know how pressure decreases? At what rate? Is it linear?
 
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  • #2
I should point out, I do know how to calculate pressure loss across the length of a pipe. That is not what I am interested in.
 
  • #3
DinjiP said:
I should point out, I do know how to calculate pressure loss across the length of a pipe. That is not what I am interested in.
Pipe friction is termed major losses, pressure drop due to fittings like valves, tees, or in your case a reducer (specifically a 6" to 1" reducer) are termed minor losses and are even easier to calculate. You can find an overview here:
http://www.engineeringtoolbox.com/minor-loss-coefficients-pipes-d_626.html
You'll have to do some more searching to find the minor loss coefficient for your specific fitting.
 
  • #4
Pressure change, both due to velocity change and due to friction losses is a function of velocity. Since your starting pressure is high, if your velocity happens to be low, the pressure change may well be negligible.
 

1. What causes pressure changes in pipes?

Pressure changes in pipes can be caused by a variety of factors, such as changes in flow rate, changes in elevation, or changes in pipe diameter. These changes can be influenced by external factors like pump operation or valve adjustments, or internal factors like clogs or blockages in the pipe.

2. How does pressure affect the flow of liquids in pipes?

Pressure plays a crucial role in the flow of liquids in pipes. In general, higher pressure will result in a faster flow rate, while lower pressure will result in a slower flow rate. This is due to the fact that pressure is directly related to the amount of energy that can be transferred to the liquid, which in turn affects its velocity.

3. How can pressure changes in pipes be measured?

Pressure changes in pipes can be measured using a pressure gauge, which is a device that measures the force of the liquid against a surface. This force, or pressure, can then be converted into different units, such as pounds per square inch (psi) or kilopascals (kPa).

4. What are the potential consequences of pressure changes in pipes?

Pressure changes in pipes can have a variety of consequences, depending on the specific situation. In some cases, it can result in leaks or bursts in the pipe, which can cause damage and require costly repairs. In other cases, pressure changes can affect the performance of equipment or systems that rely on the liquid flow, such as water pumps or heating systems.

5. How can pressure changes in pipes be controlled?

There are several ways to control pressure changes in pipes. One method is by adjusting the flow rate, which can be done by altering the pump speed or opening/closing valves. Another method is by using pressure regulators, which can maintain a consistent pressure within a designated range. Proper maintenance and regular inspections can also help prevent pressure changes and detect any potential issues before they become major problems.

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