What is the primary purpose of the BAK-14 heaters?

The primary purpose of the BAK-14 heaters is to keep air in pneumatic tubes ice-free. These heaters are designed to prevent the formation of ice in pneumatic tube systems, which can lead to blockages and malfunctioning of the systems that rely on the smooth flow of air. By ensuring that the air remains at a temperature above freezing, the BAK-14 heaters help maintain the efficient operation of pneumatic systems, especially in colder environments where ice formation is a risk. This is crucial for avionic and other systems where pneumatic tubes are used for actuation, signals, or other purposes.

The other choices focus on different functions that are not the central aim of the BAK-14 heaters. Increasing operating speed pertains to mechanical systems and performance enhancements, heating hydraulic fluid relates more to fluid systems and pumps, and maintaining structural integrity suggests a role in supporting the physical framework of machinery or aircraft, all of which are not the primary intended use of the BAK-14 heaters.