Inflatable plug assembly for borehole

A plug assembly suitable for use in the plugging of boreholes comprising an inflatable main body having an internal chamber therein, a pressurized container operatively mounted to the main body, the pressurized container having a pressurized working fluid existing as a liquid phase component and a gas phase component, the pressurized container having a discharge outlet in fluid communication with the internal chamber, the discharge outlet having an actuator operable to seal or open fluid communication of the discharge outlet with the internal chamber, the plug assembly capable of adopting alternate working modes including one working mode in which the liquid phase of the working fluid is adjacent to the pressure container discharge outlet and a second working mode in which the gas phase of the working fluid is adjacent to the pressure container discharge outlet, wherein operation of the actuator to an open position releases pressurized working fluid through the discharge outlet into the internal chamber causing inflation of the main body.