The present invention relates to a portable pressure container for driving a medical device, the container comprising: - a pressure housing (101 201 301 401 501) confining an interior volume (103 203 303 403 503), - a pressure outlet (102 202 302 402 502) extending through the pressure housing (101 201 301 401 501), - wherein the interior volume (103 203 303 403 503) comprises a liquid storage portion (105 205 305 405 505) and a gas storage portion (104 204 304 404 504), wherein the liquid storage portion (105 205 305 405 505) and the gas storage portion (104 204 304 405 505) are in flow connection with each other, - wherein the liquid storage portion (105 205 305 405 505) is configured to store a liquid phase (15) of a driving medium (10) and wherein the gas storage portion (104 204 304 404 504) is configured to store a gas phase (14) of the driving medium (10), and - wherein the pressure outlet (102 202 302 402 502) is only in flow connection with the gas storage portion (104 204 304 404 504).
