The Collaborative International Dictionary
Center seal
Center seal \Cen"ter seal\, or Centre seal \Cen"tre seal\ (Gas Manuf.) A compound hydraulic valve for regulating the passage of the gas through a set of purifiers so as to cut out each one in turn for the renewal of the lime.
Usage examples of "center seal".
Approaching closer still, she put a hand on his shirt and ran a finger up and down the center seal.