How do I calculate the maximum flow rate?

In summary, the conversation discusses the determination of maximum flow rate through a building's water outlet, taking into consideration the head loss caused by pipe size and length. The speaker suggests using online calculators for piping losses to aid in this determination. They also raise questions about the relationship between flow rate and inlet pressure, and the effect of decreasing inlet pressure on flow rate.
  • #1
TSN79
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A building has a water inlet and outlet. The static water pressure at the buildings water intake is 5 bar. I'm trying to determine how much water this outlet will deliver when its valve is fully open. In that state, the pipe size and length will result in a certain head loss that I can calculate for a spesific flow. But how can I determine what the maximum flow rate will be?
 
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  • #2
There are numerous online calculators for piping losses. One of them might be able to help you.
 
  • #3
anorlunda said:
There are numerous online calculators for piping losses. One of them might be able to help you.
Calculating the losses isn't really the issue. It's understanding what happens once the inlet pressure starts to drop due to the high flow rate. Will maximum flow rate be achieved once the inlet gauge pressure falls to zero? Or does the gauge pressure during flow need to be at least equal to the head loss through the pipe in order to overcome this?
 
  • #4
TSN79 said:
the inlet pressure starts to drop due to the high flow rate

That's how losses are defined.
 
  • #5
TSN79 said:
Calculating the losses isn't really the issue. It's understanding what happens once the inlet pressure starts to drop due to the high flow rate. Will maximum flow rate be achieved once the inlet gauge pressure falls to zero? Or does the gauge pressure during flow need to be at least equal to the head loss through the pipe in order to overcome this?

Translation: "Calculating the losses isn't really the issue. It's calculating the losses and their effect on flow rate."
 
  • #6
TSN79 said:
Calculating the losses isn't really the issue. It's understanding what happens once the inlet pressure starts to drop due to the high flow rate. Will maximum flow rate be achieved once the inlet gauge pressure falls to zero? Or does the gauge pressure during flow need to be at least equal to the head loss through the pipe in order to overcome this?

When the valve is fully open, the pressure at the outlet is zero (gauge pressure). The pressure at some point upstream is 5 bar. The head loss in between is (5 - 0) = 5 bar. You only need to calculate the flow rate at which this is the case. If the pressure at the building inlet drops, then you need to calculate farther upstream.
 
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1. What is the formula for calculating maximum flow rate?

The formula for calculating maximum flow rate is Q = VA, where Q is the flow rate, V is the velocity of the fluid, and A is the cross-sectional area of the pipe or channel.

2. How do I measure the velocity of the fluid?

The velocity of the fluid can be measured using a flow meter, which uses various methods such as ultrasonic, electromagnetic, or pressure sensors to determine the velocity of the fluid.

3. Can I calculate maximum flow rate without knowing the velocity?

No, the velocity of the fluid is a crucial component in calculating maximum flow rate. Without knowing the velocity, it is not possible to accurately determine the flow rate.

4. What factors affect the maximum flow rate?

The maximum flow rate is affected by various factors such as the diameter and length of the pipe or channel, the viscosity of the fluid, and the presence of any obstacles or bends in the flow path.

5. How do I adjust the maximum flow rate for different fluids?

To adjust the maximum flow rate for different fluids, you will need to take into consideration the specific gravity and viscosity of the fluid, as well as any other relevant properties that may affect the flow rate. These values can be used in the formula to calculate the maximum flow rate for the specific fluid.

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