Computing devices such as personal computers, laptop computers, tablet computers, cellular phones, and countless types of Internet-capable devices are increasingly prevalent in numerous aspects of modern life. As such, the demand for data connectivity via the Internet, cellular data networks, and other such networks, is growing. However, there are many areas of the world where data connectivity is still unavailable, or if available, is unreliable and/or costly. Accordingly, additional network infrastructure is desirable.
Some systems may provide network access via a balloon network operating in the stratosphere. Because of the various forces experienced by these balloons during deployment and operation, there is a balancing of needs between flexibility and stability of materials. The balloons may be made of an envelope material configured in sections or lobes to create a “pumpkin” or lobed balloon. The lobes are supported by a plurality of tendons.
Before a balloon can be deployed, its envelope must be inflated with lighter than air lift gas. Helium and hydrogen gases are two alternatives for lighter and air lift gases. Helium is an inert gas and thus considered generally safe. With helium, filling features can be sealed with O-rings, check vales, or caps in a manual setting. As an example, a person may remove a cap from a filling port, insert a filling hose, pull out the filing hose, and cap the filling port. When the filling hose is removed, gas can escape from the balloon. Even traditional one-way valves may allow a small amount of gas to leak. Purging after closing the valve, but prior to disconnecting the fill line can prevent leaks, but adds additional complexity to the design. However, with helium prices on the rise and reduced availability, hydrogen is becoming a more economical option. However, as hydrogen is highly explosive when combined with air, its use can present safety issues, especially during inflation.