Abstract: A process for manufacturing carbon membranes having controlled pore sizes comprises the steps of: a) causing a stream of a pyrolysable carbon-containing gas to come into contact with a carbon membrane having a pore size and/or distribution larger than the desired pore size and/or distribution; b) raising the ambient temperature of the said membrane to or above the temperatures at which the adsorbed carbon-containing gas pyrolyzes; and c) substantially purging the atmosphere surrounding the membrane from carbon-containing gas.

Abstract: A method of selective clogging of failed hollow fibers of a membrane module, including a pack or bundle of fibers in a shell-side and bore-side arrangement which includes failed fibers and non-failed fibers, comprises the steps of: clogging bores of all of the fiber at one end of the pack or bundle of the fibers; substantially evacuating the membrane module both at the shell-side and at the bore-side; filling the bore-side and the shell-side with a non-permeant gas; subsequently-holding the membrane module vertically, disconnecting the bore-side of the membrane module from a supply of the non-permeant gas and dipping another end of the membrane module opposite to the clogged end into a reservoir containing a liquid sealant; applying a reduced pressure to the shell-side for a period of time sufficient to permit suction of sealant into the bores of the failed fibers through a failure of which vacuum is applied to the bore-side; allowing the sealant to solidify at least partially to clog the bores of both the fa