The device comprises a sleeve that is radially expandable under the action of an inflation fluid so as to press the sleeve hermetically against the wall of the pipe or the well, said sleeve being fastened to end members. In a fuel cell system that generates power by supplying fuel gas and oxidant gas, the output of the fuel cell is measured when a temperature of the fuel cell after the actuation below freezing temperature exceeds 0 degree, and if a value of the output is equal to or less than a reference output value, pressure pulsation is applied to a cathode electrode to drain water built up in the fuel cell. A method of cleaning ink residue from an electrostatic sensing element of an ink drop detector, and a printing mechanism having such a unidirectional waste ink removal system are also provided. A service corridor is provided on selected dwelling unit levels which may be accessed by a service elevator or spaced apart stairways to provide secondary access between each dwelling unit on each dwelling unit level and street level. In this manner, the platen separates from the thermal head, and setting a recording sheet becomes easier.