The Nitrogen Portable Charging Kit provides a convenient and easy to use method of topping up aircraft door systems and tires. Light enough to be easily handled by one person, the kit is housed in a robust, shower proof shoulder carry bag, with a double zip to allow easy access and visibility of the cylinder content gauge, regulator and fill pressure gauge. The regulator and relief valve assembly are housed in a damage resistant close foam protective lining, incorporating a 1.5m charge/connection hose and Shrader connection on the hose end for easy connecting to door assist bottle.