High school chemistry taught you PV=nRT. But at 100 bar and 500°C, propane doesn't behave nicely. ISO 23251 dedicates pages to the "Compressibility Factor." The PDF is valuable because it holds the complex equations of state (Redlich-Kwong, Soave, etc.) that tell you how the fluid actually behaves just before everything blows up.
API 521: Fire Relief Evaluation Methods | PDF | Heat Transfer iso 23251 pdf
Whether you pay for the official PDF or access it via an engineering subscription, remember: You aren't just looking at a file. You are looking at the collective survival knowledge of the hydrocarbon industry, distilled into 100 pages of unforgiving math. High school chemistry taught you PV=nRT
Imagine a storage tank sitting in a pool of burning gasoline. The liquid inside boils, vaporizes, and pressure skyrockets. ISO 23251 provides the exact formula to calculate how much vapor is generated. If you get this wrong by 10%, the tank doesn't burst; it turns into a rocket-propelled projectile. The PDF contains the wetted area charts that save lives. API 521: Fire Relief Evaluation Methods | PDF