How Many Are Required?
"Rule of Thumb" Guide for Installing 100lb. Cylinders
For continuous draw where temperatures may reach zero F. Assume the vapourization rate of a 100 lb. cylinder as approximately 50,000 BTU per hour.
Number of cylinders per side = total load in BTU's divided by 50,000
Example
Assume total load = 200,000 BTU/hr
Cylinders per side = 200,000 / 50,000 = 4 cylinders per side
Vapourization Rate 100lb Propane Cylinders (Approximate)
Maximum Continuous Drawn in BTU per Hour at Various Temperatures in Degrees F
| Lbs of LPG in Cyl. | 0 degrees F | 20 degrees F | 40 degrees F | 60 degrees F | 70 degrees F |
| 100 | 113,000 | 167,000 | 214,000 | 277,000 | 300,000 |
| 90 | 104,000 | 152,000 | 200,000 | 247,000 | 277,000 |
| 80 | 94,000 | 137,000 | 180,000 | 214,00 | 236,000 |
| 70 | 83,000 | 122,000 | 160,000 | 199,000 | 214,000 |
| 60 | 75,000 | 109,000 | 140,000 | 176,000 | 192,000 |
| 50 | 64,000 | 94,000 | 125,000 | 154,000 | 167,000 |
| 40 | 55,000 | 79,000 | 105,000 | 131,000 | 141,000 |
| 30 | 45,000 | 66,000 | 85,000 | 107,000 | 118,000 |
| 20 | 26,000 | 51,000 | 68,000 | 83,000 | 92,000 |
| 10 | 28,000 | 38,000 | 49,000 | 60,000 | 66,000 |
This chart shows the vapourization rate of containers in terms of temperature of the liquid and the wet surface area of the container. When temperature is lower, or if the container has less liquid in it, the vapourization rate of the container is a lower value.
