- Pneumatic reservoirs are intended for use in aircraft and missile pneumatic systems, which may include a compressor for recharging the system during flight, or may be of the ground-charge type.

The compressor-type system will usually include a spring-loaded pressure or thermal relief valve, which, upon increase in temperature, will serve to vent some of the content of the reservoir and thus avoid overpressure. For such systems, the type 15-20 or 30-40 reservoirs should generally be used, with class designation depending on the maximum in-flight temperature.

The ground-charge type system will usually not include a spring-loaded relief valve, therefor an increase in temperature will result in increased pressure. For such systems, the maximum in-flight temperature will determine the class used, and the resulting maximum temperature-induced pressure will determine the type used.

Pressure-temperature relationship for reservoirs without relief valves, and charged to rated (type) pressure at 70°F are listed in table IV.