Calculate Air Flow in SS SCH40 1" Pipe | 80 psi at Discharge

In summary, the SS SCH40 1" pipe can only handle a pressure of 80 psi at the discharge point, but it can still discharge to atmospheric pressure.
  • #1
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The following is the only information that is given at this point in time:
Air flow through SS SCH40 1" pipe (ID 1.048"). Pressure required is 80 psi at the discharge point. Assume supply pressure is 100 psi and unlimited in quantity at a constant pressure, supplied from a tank. The pipe will discharge to atmospheric pressure.

I can't seem to remember how to determine how to calculate flow rate or velocity of the air based only on these values. I feel that I need more information to be able to calculate equivalent length at the very least, but even assuming a arbitrary length, I am having problems on figuring out how to approach this problem.

Any help here will be appreciated. (switching gears from chemical reactions to this stuff at 4pm is killing me)

I'll try to check back and answer any other questions so that I can get a quick answer.

Thanks!
 
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  • #2
Welcome to PF.

80 psi is above the pressure for choked (supersonic) flow, so that is the maximum you could get air to flow through the pipe at pressure.

Also, these two sentences:
pressure required is 80 psi at the discharge point...

...The pipe will discharge to atmospheric pressure.
...contradict each other. The pressure at the discharge point is always atmospheric pressure and unless there is an orifice or some other obstruction at the discharge point, the pressure right before it will also be atmospheric.

So could you explain in some more detail what you are trying to do?
 
  • #3
Sorry I didn't proof read what I wrote.

Anyways -
I'm trying to size an accumulator. It's for a cleaning cycle on a filter that requires a constant flow of 80 psi air for 5 minutes. The length of pipe is in question right now, but it would be safe to assume an equivalent length of 150 ft. Supply air temperature would be around 80 F. The compressor supplying the air to the accumulator supplies air at 100 psi.

Sorry for the confusion - I'll check back here throughout the day.
 

1. How do I calculate air flow in a SS SCH40 1" pipe at 80 psi discharge?

To calculate air flow in a SS SCH40 1" pipe at 80 psi discharge, you can use the following formula:

Q = A x V

Where Q is the air flow rate, A is the cross-sectional area of the pipe, and V is the velocity of the air. To find the cross-sectional area, use the formula:

A = π x (d/2)^2

Where d is the diameter of the pipe. To find the velocity, use the formula:

V = (0.407 x √(P/ρ)) / d

Where P is the pressure in psi and ρ is the density of air at standard conditions (0.075 lb/ft³). Plug in the values and solve for Q to get the air flow rate in cubic feet per minute (CFM).

2. What is the maximum air flow rate for a SS SCH40 1" pipe at 80 psi discharge?

The maximum air flow rate for a SS SCH40 1" pipe at 80 psi discharge depends on several factors, including the length of the pipe, the temperature and humidity of the air, and the presence of any obstructions or fittings in the pipe. Using the formula mentioned in the previous answer, you can calculate the maximum air flow rate for your specific conditions.

3. Can I use a different formula to calculate air flow in a SS SCH40 1" pipe at 80 psi discharge?

Yes, there are other formulas that can be used to calculate air flow in a pipe, such as the Darcy-Weisbach equation or the Hazen-Williams equation. However, these formulas may require additional information and may be more complex to use. The formula provided in the first answer is a simplified version that can give a good estimate of air flow rate.

4. How does the pressure affect air flow in a SS SCH40 1" pipe at 80 psi discharge?

The pressure in a SS SCH40 1" pipe at 80 psi discharge directly affects the air flow rate. As the pressure increases, the air flow rate also increases. This is because the higher pressure creates a greater force, which results in a higher velocity of the air through the pipe.

5. Is the air flow rate in a SS SCH40 1" pipe at 80 psi discharge affected by the material of the pipe?

The material of the pipe may have a small impact on the air flow rate, but it is not a significant factor. The main factors that affect air flow rate in a pipe are the pipe diameter, length, and any obstructions or fittings present. As long as the pipe is made of a material that can withstand the pressure and does not create any obstructions, the material should not greatly impact the air flow rate.

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