This page is a guide for controlling airflow. One method for the control of the flow of a gas involves three main components: a source, an adapter, and a valve.
The source is the origin of the air. One easy to find/use source is a CO2 canister. These deliver compressed CO2 gas at 800-900 psi. To ensure air tightness, the threading of the canister should be wrapped in teflon tape approximately 6 times.
The adapter allows for the source to be connected to the valve. This component requires much more creativity than the source or the valve. One specific way this has been done is using a custom-made part like the one pictured. The function of this specific part is two-fold: 1) it punctures the air source 2) it connects the source to the valve. To puncture the canister, the custom-made part uses a hollow metal tube that rests on a bevel within the part. When the compressed air source is turned into the part, the torque on the source by the tube pops open the flat surface of the canister. In addition to this part, a pressure regulator is also recommended in some cases. Pressure regulators act to step-down the pressure from an air source to account for valves that are not graded for the 800-900 psi of a CO2 canister. If you use a regulator, you may also want to find a properly sized male to male converter so that you can connect the regulator to the valve.
This part is what actually controls the air flow. Solenoid valves are most commonly used here. Given a voltage input, the solenoid valve will open, allowing the air from the source to flow through the adapter and the valve to its destination. A common way to control a valve is with a an Arduino, which can be coded to deliver a voltage to the valve only upon certain circumstances. For instance, an accelerometer can be used in conjunction with an Arduino to deliver a voltage to the valve only when the accelerometer measures a certain threshold of acceleration. This specific method can be used to allow air to flow into an airbag when the accelerometer senses a drop. There are many different kinds of solenoid valves. Be careful to match the valve with an appropriate air source, so that the pressure grade of your solenoid valve is not exceeded by the pressure of the source. However, at the same time, make sure that the valve is pressure rated high enough that it can deliver the air pressure needed for your specific destination.