A fuel-cell system, in particular for a vehicle, has a device for supplying the operating agents for a fuel cell and an electrical energy accumulator. The method includes applying first torque to the distal end of the medical device by creating magnetic moment at the distal end of the medical device, and applying a second torque to the distal end of the medical device. The monitoring system may further include a sensor configured to selectively receive a first sample flow of the first chemical mixture from the first chemical vessel and a second sample flow of the second chemical mixture from the second chemical vessel. The eductor is positioned proximate the downstream end.