Understanding Pressure in a Pipe System

In summary, the pressure of water flowing through a pipe will decrease as it encounters friction from bends and turns. This is important to consider when designing radiator systems for houses. Additionally, while water is virtually incompressible, the pressure will increase as the volume decreases in a pipe. In order for anything to flow, there must be a difference in pressure.
  • #1
TSN79
424
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Let's say we have water flowing in a pipe under so and so pressure at a given point. Now the water flows through bends, turns and straight lines of pipe. Will the pressure after a distance be lower than it was at the starting point, due to friction in the pipes and bends and such? Or will the pressure be constant at all points? The pipe dimension is constant.

I'm asking 'cause we're learning about radioators in houses, and the fact that one must account for what I can translate to mean "pressure drop" as the water flows through the system. I'm just having a bit of trouble believing that the pressure is different at different locations in the system. If we measure 3 bars just after the pump, won't the pressure be 3 bars everywhere in the system...?

Secondly I wonder about this; if we place water in a pipe at let's say 2 bars, does that mean that we have pushed more water into the pipe than there's actually room for? In other words; have we compressed the water? I didn't think that was possible...?

I'm confused, please someone help me! :confused:
 
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  • #2
TSN79 said:
I'm just having a bit of trouble believing that the pressure is different at different locations in the system. If we measure 3 bars just after the pump, won't the pressure be 3 bars everywhere in the system...?
If the fluid is static, you are right. But if it is moving, the friction force multiplied by the distance moved requires energy. Pressure is the energy density of the fluid. If the fluid does work, the energy of the fluid (pressure) has to decrease.

Secondly I wonder about this; if we place water in a pipe at let's say 2 bars, does that mean that we have pushed more water into the pipe than there's actually room for? In other words; have we compressed the water? I didn't think that was possible...?
Since water is virtually incompressible, there is very little reduction in volume. But that just means that the pressure increases significantly for a very small reduction in volume.

AM
 
  • #3
For anything to flow in a pipe from point A to point B there MUST be a difference in pressure. In your example, water is flowing in pipes. Even if you had a straight pipe that had no restrictions or enlargements, bends or turns, there would still be a pressure drop along the length of the pipe. That is due to friction developed as a result of the fluid's viscocity. When you start to add things like elbows, tees and the like to go to all of the different items in a house, each one of those small items adds a bit more resistance to the flow. As a matter of facet, we equate the losses induced by these items in terms of an equivilent length of straight pipe.

Just remember, in the real world, for anything to flow, there must be a difference in pressure.
 

1. What is pressure in a pipe system?

Pressure in a pipe system is the force exerted on the walls of the pipe by the fluid flowing through it. It is typically measured in units of pounds per square inch (PSI) or kilopascals (kPa).

2. What causes pressure in a pipe system?

The pressure in a pipe system is primarily caused by the weight of the fluid in the pipe, as well as any additional forces such as pumps or gravity. The higher the height of the fluid, the greater the pressure.

3. How is pressure calculated in a pipe system?

The pressure in a pipe system can be calculated using the formula P = F/A, where P is the pressure, F is the force exerted by the fluid, and A is the cross-sectional area of the pipe. This formula can be used for both liquid and gas fluids.

4. What factors can affect pressure in a pipe system?

Several factors can affect pressure in a pipe system, including the type of fluid, the flow rate, the diameter of the pipe, the length of the pipe, and any changes in elevation. Additionally, any obstructions or restrictions in the pipe can also impact pressure.

5. How can pressure be controlled in a pipe system?

Pressure in a pipe system can be controlled by adjusting the flow rate, using valves to regulate the amount of fluid flowing through the system, or using devices such as pumps or pressure regulators to maintain a specific pressure level.

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