Isopropyl nitrate

Isopropyl nitrate (IPN, 2-propyl nitrate) is a colorless liquid monopropellant. It is used as a diesel cetane improver. IPN is a low-sensitivity explosive, with a detonation velocity of approximately 5400 m/s.

Isopropyl nitrate is extremely flammable and burns with a practically invisible flame. This presents unique hazards in its handling. The flame is significantly less luminous than hydrogen or methanol flame and is only visible due to the turbulent hot air it generates.

Isopropyl nitrate was previously used in a jet engine starting system for military interceptor aircraft, and was known as AVPIN. The exhaust fumes from an AVPIN monopropellant engine may themselves be explosive, if mixed with further air. Early systems, as used on the Gloster Javelin, used a simple pressurising cartridge and had a poor reputation for misfires, including engine-destroying explosions. Nevertheless, Rolls Royce was able to demonstrate that the fuel is extremely stable and that a cannon shell could be fired through a container of it with no dramatic effect. Isopropyl nitrate was also sold by the Turbonique company under the brand name "Thermolene" as a fuel for their line of turbine-powered "drag axles" and superchargers, during the 1960s.