Why can helium balloons only float for a few hours?

This is because helium is very permeable and will leak out from the cracks of rubber molecules. Therefore, in general, the floating time of helium balloon with 10 inch (with a transverse diameter of 25 cm) is 5- 10 hour, and that of helium balloon with 12 inch (with a transverse diameter of 30 cm) is 24 hours.

By adding special balloon protective liquid, a protective film is formed on the inner wall of the balloon, which can prolong the floating time of the balloon. 10 inch can float for more than 24 hours, and 12 inch can float for more than 72 hours.

Reasons for banning helium balloons

In order to raise money for poor families and children, charity organizations in Cleveland, USA organized a super-large charity balloon festival at 1986. All the balloons were sold at a price of one dollar, and all the income was donated to the relief fund for poor families. It was planned to sell 2 million balloons, but due to the bad weather at that time, 70% of the target was achieved, and about 654.38+0.4 million balloons were planned to be released in a unified way.

Such creative activities have received unprecedented support, and the crowd of onlookers is endless. In order to achieve the maximum effect, the organizer decided to release it together, which won the unanimous support of the people at the scene, but never thought that a disaster was approaching! After these balloons were released, they didn't fly away as soon as expected. Because the air was cold that day and the helium density was slightly higher, the floating effect was not good. They stay at low altitude and float around!

What's more, the balloons of large troops floated to Cleveland airport, which caused several planes to make an emergency landing and forced the airport to close. These wandering helium balloons also caused an accident on the expressway. Finally, leaking helium balloons can be seen everywhere around the city, even causing fishermen to drown. Finally, the organizer was sued and compensated for millions.