Diborane is used in silicon chip manufacture. One facility uses a 500-lb bottle. If the entire bottle is released continuously during a 20-min period, determine the location of the 5 mg/m3 ground-level isopleth. It is a clear, sunny day with a 5 mph wind. Assume that the release is at ground level. Assume now that the bottle ruptures and that the entire contents of diborane are released instantaneously. Determine, at 10 min after the release,

We want to determine the location after 10mins

Explanation:

The release of diborane is continuous

It is release at a rate of 500lb per 20mins

Then, let find the rate in mg/s

1 lb = 453592.37 mg

So, the mass rate Q is

Q = 500lb / 20mins

Q = 500 * 453592.37 mg / 20 * 60sec

Q = 188,996.82 mg/s

Given that mass concentration of

m~ = 5mg/m³

Then,

Rate of volume is

V~ = Q / m~

V~ = 188,996.82 / 5

V~ = 37,799.364 m³/s

The wind speed is

V = 5mph

Let convert to m/s

1 mph = 0.447 m/s

Then, 5mph = 2.235 m/s

From Pasquill Gilford, the cloud atmosphere characteristic is class A

To know the location, we will divide the velocity by heat rate

X = V / Q

X = 2.235 / 188,996.82 mg/s

X = 2.235 / 0.188996kg/s

X = 11.83 m / kg

The location is 0.000001183 m per mg of diborane