How to calc force from natural gas?

[doug12345]

Hi, I'm looking for some help in calculating the amount of force from natural gas exploding. Part of the problem is that it causes a wall from a house to fail first. Area of wall 875 SF. Wall depth .25 ft. I was going to assume the whole wall to be the boundry conditions for the volume that gas can fill. (V=219 CF)

The explosive limits of the gas can be 4%-15% of volume. (Vgas=8.76 to 32.85 CF)

Then from wikipedia I found 1 CF gas = 1030 BTU, 1 BTU = 780 ft*lbf (ft-lbs-force)
Next 8.76*(1030)*(780)= 7037784 ft*lbf to 26391690 ft*lbf

Is it then possible to divide the 7037784 ft*lbf by the length of the wall to obtain a distributed load in lb/ft? Am I even approaching this problem correctly?

Thanks

 

[Lojzek]

A better approach would be:

1. Calculate the energy of the gas.
2. Divide it by mass of the air inside the room*specific heat if the air
to get the increase of temperature.
3. Use ideal gas equation to calculate the change of pressure (p2/p1=T2/T1).

 

[charng]

for reaching out and sharing your problem with calculating the force from a natural gas explosion. I can provide some guidance on how to approach this problem.

Firstly, it is important to understand the principles of force and how it is calculated. Force is defined as the product of mass and acceleration, or in mathematical terms, F=ma. In this case, the force from a natural gas explosion would be due to the acceleration of the gas as it expands and pushes against the surrounding walls.

To calculate the force from the gas explosion, we need to consider the volume of gas involved and the pressure it creates. The volume of gas can be determined by the explosive limits mentioned in the content, which range from 8.76 to 32.85 cubic feet (CF). The pressure can be calculated using the ideal gas law, which states that pressure (P) is equal to the number of moles of gas (n) multiplied by the gas constant (R) and the temperature (T) divided by the volume (V). In this case, the temperature can be assumed to be constant at room temperature.

Once the pressure is calculated, we can use it to determine the force exerted by the gas on the walls of the house. This can be done by multiplying the pressure by the surface area of the walls, which is given as 875 square feet (SF) in the content. This will give us the total force exerted by the gas on the walls of the house.

It is important to note that the force exerted by the gas will not be evenly distributed along the length of the wall, as the explosion may occur at a specific point and the force will decrease as the gas expands. Therefore, it would not be accurate to divide the total force by the length of the wall to obtain a distributed load in pounds per foot (lb/ft).

In conclusion, to calculate the force from a natural gas explosion, we need to consider the volume of gas involved, the pressure it creates, and the surface area of the walls. It is also important to keep in mind that the force may not be evenly distributed along the walls and may vary depending on the location of the explosion. I hope this helps you approach the problem in a more accurate and scientific manner.