Flammability Limits in Air
| Component | LFL (vol%) | UFL (vol%) | Autoignition (°F) |
|---|
| Methane | 5.0 | 15.0 | 999 |
| Ethane | 3.0 | 12.4 | 882 |
| Propane | 2.1 | 9.5 | 842 |
| n-Butane | 1.8 | 8.4 | 761 |
| n-Pentane | 1.4 | 7.8 | 500 |
| n-Hexane | 1.2 | 7.4 | 437 |
| Hydrogen | 4.0 | 75.0 | 932 |
| H₂S | 4.0 | 44.0 | 500 |
| Natural Gas | 4.5-5.0 | 14.5-15.0 | 900-1000 |
Toxicity Limits
| Substance | IDLH (ppm) | PEL-TWA (ppm) | STEL (ppm) | Effects |
|---|
| H₂S | 100 | 10 | 15 | Highly toxic, odor fades |
| CO | 1200 | 50 | 400 | Asphyxiant, odorless |
| Benzene | 500 | 1 | 5 | Carcinogen |
| Toluene | 500 | 200 | 300 | CNS effects |
| SO₂ | 100 | 2 | 5 | Respiratory irritant |
| NH₃ | 300 | 50 | 35 | Corrosive, pungent |
| Mercury | 10 mg/m³ | 0.05 mg/m³ | 0.1 mg/m³ | Cumulative poison |
| Methanol | 6000 | 200 | 250 | Toxic by all routes |
Relief Valve Sizing Factors
| Fluid | Kb | Kc | Kd | Comments |
|---|
| Natural Gas | 1.00 | 1.00 | 0.975 | Base case |
| Ethane | 1.13 | 1.00 | 0.975 | Higher MW |
| Propane | 1.26 | 1.00 | 0.975 | Higher MW |
| Steam | 1.00 | 1.00 | 0.975 | Common utility |
| Air | 0.95 | 1.00 | 0.975 | Lower MW |
| Hydrogen | 0.43 | 1.00 | 0.975 | Very low MW |