| Mechanical & Fluid Systems

Novel Vent Design Features Variable Flow Control and Rain Protection

Applications include space, military, and commercial rockets; HVAC systems; and automobile ventilation systems.

NASA’s Marshall Space Flight Center scientists have designed a vent that can be useful for purging closed compartments, while preventing backflow and foreign object entry. The technology uses a system of configurable devices to provide variable flow control and prevent water, insects, or undesired gases from entering a vented space. The technology is effective even in high winds, while conventional rocket vent systems that use mesh screening, flapper valves, and high-flow-rate purge gas to protect sensitive equipment are not completely effective in extreme weather conditions.

Developed for venting and balancing flow in closed rocket compartments — which is critical for NASA, the military, and commercial rocket manufacturers — the design is useful for any device needing a one-way purge valve, flow balancing between compartments, or a general air vent where rain and gas reverse entry must not occur. The system also concentrates generated acoustic energy in a forward cone, and can direct noise away from certain areas such as work platforms.

Rockets must have a dry gas purge system to keep flammable vapors and water out of closed compartments while they are assembled, await launch, and undergo actual flight. The system operates in a single-flow direction, creating a oneway vent design. By changing its configuration, gas flow can be optimized. Similarly, the system can greatly increase the operational flow range of the vent, as the device automatically adapts to higher or lower flow conditions. Devices within the system can possess different operational flow characteristics, enabling gas balancing or control that directs flow where needed. The system can be configured for a rocket purge application that requires low flow purge conditions, such as rocket storage. As the purge requirement increases (pre-flight tank loading or rocket ascent), the gas flow rate increases. If the purge gas flow stops, the system closes completely and automatically, protecting the compartment from water, insects, animals, humidity, and outside contaminants.

Conventional gas purge systems operate only at high flow rates, and even then, are not always effective. For example, high wind conditions encountered on launch pads allow humid air into purge spaces, and the mesh screening can sometimes be ineffective in preventing small-insect entry. Conversely, this new NASA design can control and balance flow rates across multiple vent locations operating at different gas flow ranges while protecting sensitive electronics from animal and insect entry, gas back-flow, rain entry, condensation, humidity, and flammable gas accumulation.

NASA’s Technology Transfer Program offers commercial licensing agreements to ensure its pioneering research finds secondary uses that benefit the economy, create jobs, and improve quality of life. For more information about licensing, please contact Clark Darty at This email address is being protected from spambots. You need JavaScript enabled to view it. or 256-544-2728.