🔍 Key Concepts

• Hydrogen sulfide (H2S) toxicity and how quickly it can incapacitate personnel • Differences between emergency escape devices and working/entry breathing apparatus • The importance of positive-pressure / pressure-demand systems in toxic gas environments

💭 Think About

• Which option is designed for short-term escape only, and which are designed for doing repair or investigative work in a contaminated area? • In an H2S environment, why is maintaining positive pressure inside the facepiece critical, and which option(s) provide that? • Among the SCBA types listed, how does air flow to the user—only when they inhale (demand), or is the system kept at a slight positive pressure (pressure-demand)?

✅ Before You Answer

• Confirm which device(s) are classified primarily as escape-only equipment, not for entry/repair work • Identify which choice provides a positive-pressure seal to prevent H2S from leaking in if the mask loses suction briefly • Verify which option is normally recommended in standards and guidance for entry into known H2S atmospheres on offshore units like MODUs