When the pressure gauge on a size E N2O cylinder begins to fall from 750 psi, approximately how many liters remain?

When the pressure gauge on a size E N2O cylinder begins to fall from 750 psi, approximately how many liters remain?

• A. 200 L
• B. 400 L
• C. 600 L
• D. 800 L

Answer: (B)

Nitrous oxide in an E cylinder is stored largely as a liquid with a large amount of gas in the headspace. The pressure gauge stays around 750 psi while liquid remains, so that pressure plateau isn’t a good indicator of how much gas is left. When the pressure begins to fall from that level, it means the reservoir of liquid is nearly exhausted and the cylinder is transitioning to a real “gas-only” phase. At that point there is still a substantial amount of gas left to be used—roughly 400 liters for an E-size cylinder. This estimate reflects the typical total gas content of a full E cylinder and the point at which the pressure starts to drop.

Nitrous oxide in an E cylinder is stored largely as a liquid with a large amount of gas in the headspace. The pressure gauge stays around 750 psi while liquid remains, so that pressure plateau isn’t a good indicator of how much gas is left. When the pressure begins to fall from that level, it means the reservoir of liquid is nearly exhausted and the cylinder is transitioning to a real “gas-only” phase. At that point there is still a substantial amount of gas left to be used—roughly 400 liters for an E-size cylinder. This estimate reflects the typical total gas content of a full E cylinder and the point at which the pressure starts to drop.