🔍 Key Concepts

• Cargo grade classifications (A, B, C, D, E) in 46 CFR for flammable/combustible liquids and their flash points • The purpose and limitations of goose neck vents with flame screens versus more sophisticated venting systems (e.g., P/V valves, flame arresters) • Which grades of cargo produce more hazardous vapors that may require higher levels of vent and flame protection

💭 Think About

• Compare which cargo grades have the lowest flash points and therefore generate the most flammable vapors that could ignite at normal temperatures • Ask yourself: for which grades would a simple goose neck with a flame screen be considered insufficient protection, requiring a more advanced venting/relief system? • Order the grades from most hazardous to least, then decide at what grade level regulations usually start allowing simpler vent arrangements

✅ Before You Answer

• Verify in 46 CFR how Grades A, B, C, D, and E are defined by flash point and vapor pressure • Check which grades are allowed to use only goose neck vents with flame screens instead of full P/V (pressure-vacuum) valves or detonation/flame arrestors • Make sure your choice reflects a limit (upper boundary) — meaning: up to and including which maximum grade those vents are permitted