The math is simple, if you remember Avogadro . Let’s use a balloon that needs 2.2 liters of helium, which is about 1/10 of a Mole , or 1/10 x 6.02 x 10 23 atoms of helium. At 3.7 x 10 4 atoms/second, it would take 6/3.7 x 10 23-4 seconds,