Formula 1 to Paragraph (a)
Where:
Q = Minimum required rate of discharge in cubic feet per minute of free air at standard conditions (60 °F and 14.7 psia).
M = Molecular weight of the product, or 86.7.
T = Temperature, degrees Rankine (460° + temperature in °F of gas at relieving temperature), or 710 °R.
A = Total external surface area of the tank compartment in square feet.
L = Latent heat of the product being vaporized at relieving conditions in Btu per pound, or 144 Btu per pound.
Z = Compressibility factor of the gas at relieving conditions, or 1.0.
C = Constant based on relation of specific heats, equal to 315.
Table 1 to § 64.63 -Minimum Emergency Venting Capacity in Cubic Feet: Free Air/Hour
[14. 7 lb/in2 a and 60 °F]
Exposed area square feet 1 | Cubic feet free air per hour | Exposed area square feet 1 | Cubic feet free air per hour |
20 | 27,600 | 275 | 237,000 |
30 | 38,500 | 300 | 256,000 |
40 | 48,600 | 350 | 289,500 |
50 | 58,600 | 400 | 322,100 |
60 | 67,700 | 450 | 355,900 |
70 | 77,000 | 500 | 391,000 |
80 | 85,500 | 550 | 417,500 |
90 | 94,800 | 600 | 450,000 |
100 | 104,000 | 650 | 479,000 |
120 | 121,000 | 700 | 512,000 |
140 | 136,200 | 750 | 540,000 |
160 | 152,100 | 800 | 569,000 |
180 | 168,200 | 850 | 597,000 |
200 | 184,000 | 900 | 621,000 |
225 | 199,000 | 950 | 656,000 |
250 | 219,500 | 1,000 | 685,000 |
1 Interpolate for intermediate sizes.
46 C.F.R. §64.63