SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/scuba-regulator-second-stage

When does a scuba regulator second stage deliver air?

When you inhale, it supplies air at ambient pressure.

Start playing free

  1. Continuously
  2. When you inhale ✔
  3. Only above 30 feet

Why: The second stage has a demand valve. Inhaling drops pressure and opens the valve, delivering air.

Huh, didn't know that: You also breathe out through the second stage, and your bubbles go into the water.

The dad joke
Why is the second stage so polite? It only speaks when it is asked to breathe.
Like this card?
Play the game

References

Answer: When you inhale. The second stage has a demand valve. Inhaling drops pressure and opens the valve, delivering air.

  1. PADI Gear: Regulators www.padi.com/gear/regulators
    Also called a demand valve because it gives you air when you demand it (inhale) at the exact pressure you need
    Checked 2026-10-12.
  2. PADI Blog: How Does Scuba Gear Work? blog.padi.com/how-does-scuba-gear-work
    Then the diver is able to exhale through the mouthpiece into the water.
    Checked 2026-10-12.

Think this answer is wrong? Tap "Challenge this answer" on the card in the game and tell us why.

Test yourself in the game

Sports & FitnessWhich part of a scuba regulator attaches to the tank and reduces high pressure?Sports & FitnessWhat is the first rule of scuba diving?Sports & FitnessWhat can happen if a diver holds their breath while ascending?

That's stuff everyone should know.