Volumetric flow rate through a pipe vented to atmosphere

In summary, the problem is to find the flow rate of the gas inside the last tube in order to size an appropriate emergency cut-off valve which we need to install in between the regulator and the end of the 25 foot tube.
  • #1
tnengineer
1
0
My chemical engineering is a little rusty after 25 years and I could use a little help with this real world problem. This isn't my project but I've been asked to advise. Sorry for the limited information.

We have a 30 gallon tank with 75% hydrogen/25% nitrogen mixture at 100 psig. From the tank there is a copper tube 0.93 inch I.D. running to a pressure regulator set to 20 psig. From the regulator there is a 25 foot copper tube(same dims) connecting to a weld box. Assume atmospheric pressure is 14.7 psia and no change in elevation from tank to final pipe end.

The problem is to find the flow rate of the gas through the 25 foot tube in the case there is an accident and the box at the end is broken loose from the pipe and the gas vents to atmosphere. I need to know the volumetric flow rate of the gas inside the last tube in order to size an appropriate emergency cut-off valve which we need to install in between the regulator and the end of the 25 foot tube.

Attached is a simple diagram of the system.

I need to know the calculations so I can explain them to my co-workers.

Any help would be appreciated.
 

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  • #2
I'm sorry you are not finding help at the moment. Is there any additional information you can share with us?
 
  • #3
tnengineer said:
My chemical engineering is a little rusty after 25 years and I could use a little help with this real world problem. This isn't my project but I've been asked to advise. Sorry for the limited information.

We have a 30 gallon tank with 75% hydrogen/25% nitrogen mixture at 100 psig. From the tank there is a copper tube 0.93 inch I.D. running to a pressure regulator set to 20 psig. From the regulator there is a 25 foot copper tube(same dims) connecting to a weld box. Assume atmospheric pressure is 14.7 psia and no change in elevation from tank to final pipe end.

The problem is to find the flow rate of the gas through the 25 foot tube in the case there is an accident and the box at the end is broken loose from the pipe and the gas vents to atmosphere. I need to know the volumetric flow rate of the gas inside the last tube in order to size an appropriate emergency cut-off valve which we need to install in between the regulator and the end of the 25 foot tube.

Attached is a simple diagram of the system.

I need to know the calculations so I can explain them to my co-workers.

Any help would be appreciated.

I don't have the time to go thru this problem in detail, but you can find a description of the method of solution in these references:

Crane Engineering Technical Publication 410 - "Flow of Fluids through Valves, Fittings, and Pipe"

A.H. Shapiro, "The Dynamics and Thermodynamics of Compressible Fluid Flow", Vol. 1, chapter 6 (1953)

M.J. Zucrow & J.D. Hoffman, "Gas Dynamics", Vol. 1, 1976

and of course, a diligent search of the web with the topic phrase 'gas dynamics' should turn up relevant information.
 

1. What is volumetric flow rate through a pipe vented to atmosphere?

Volumetric flow rate through a pipe vented to atmosphere is the volume of fluid that passes through a pipe per unit of time. It is typically measured in cubic meters per second (m3/s) or gallons per minute (GPM).

2. How is the volumetric flow rate through a pipe vented to atmosphere calculated?

The volumetric flow rate through a pipe vented to atmosphere is calculated by multiplying the cross-sectional area of the pipe by the velocity of the fluid. This can be represented by the equation Q = A x V, where Q is the volumetric flow rate, A is the cross-sectional area, and V is the velocity of the fluid.

3. What factors affect the volumetric flow rate through a pipe vented to atmosphere?

The volumetric flow rate through a pipe vented to atmosphere can be affected by various factors such as the diameter and length of the pipe, the viscosity of the fluid, the pressure difference between the inlet and outlet of the pipe, and the roughness of the pipe walls.

4. How does the venting of the pipe to atmosphere impact the volumetric flow rate?

Venting the pipe to atmosphere allows for the free flow of fluid without any restrictions or back pressure, which can increase the volumetric flow rate. However, if the vent is not properly sized or located, it can cause turbulence and decrease the flow rate.

5. Why is it important to measure the volumetric flow rate through a pipe vented to atmosphere?

Measuring the volumetric flow rate through a pipe vented to atmosphere is important for various reasons, such as monitoring the efficiency of a system, determining the amount of fluid being transported, and identifying any potential issues or blockages in the pipe. It is also necessary for proper maintenance and regulation of fluid flow in industrial processes.

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