How long does it take for two bottles to completely transfill when one is empty and one is full?

How long does it take for two bottles to completely transfill when one is empty and one is full?

• A. 15 seconds
• B. 60 seconds
• C. 45 seconds
• D. 90 seconds

Answer: (C)

Transfill time is set by how fast gas can move from the full bottle to the empty one and by how much gas needs to move to balance the pressures. When two identical bottles are connected, gas flows from the higher-pressure bottle to the lower-pressure bottle until both reach the same final pressure. It isn’t about transferring all the gas from the full bottle into the empty one; it’s about equalizing pressure between equal volumes. In typical training transfill equipment, this balancing happens in about 45 seconds, so that’s the expected duration. If the bottles were different sizes or the target pressure differed, the time would change accordingly.

Transfill time is set by how fast gas can move from the full bottle to the empty one and by how much gas needs to move to balance the pressures. When two identical bottles are connected, gas flows from the higher-pressure bottle to the lower-pressure bottle until both reach the same final pressure. It isn’t about transferring all the gas from the full bottle into the empty one; it’s about equalizing pressure between equal volumes. In typical training transfill equipment, this balancing happens in about 45 seconds, so that’s the expected duration. If the bottles were different sizes or the target pressure differed, the time would change accordingly.