A centralizer includes two stop collars configured to be affixed to an exterior surface of a pipe. A plurality of circumferentially spaced apart spacers is each coupled at each end to one of the stop collars, a first plurality of circumferentially spaced apart bow springs is each coupled at one end thereof to the first stop collar and at an opposite end thereof to a first floating collar disposed between the first and second stop collars. A second plurality of circumferentially spaced apart bow springs is each coupled at one end thereof to the second stop collar and at an opposite end thereof to a second floating collar disposed between the first and second stop collars. A shape of the bow springs is selected to cooperatively engage the spacers and the floating collars such that when compressed the centralizer provides a substantially fluid-tight seal.