Coolant recovery process

A process for recovering a coolant gas from a fiber optic cooling heat exchanger, said process comprising:

• (a) providing at least one heat exchanger having at least one passageway capable of passing therethrough at least one hot fiber, at least one inlet for passing said coolant gas into said at least one passageway and at least one outlet for removing said coolant gas from said at least one passageway;
• (b) introducing said at least one fiber into said at least one passageway of said at least one heat exchanger;
• (c) introducing said coolant gas into said at least one inlet of said at least one heat exchanger;
• (d) delivering at least a portion of said coolant gas from said at least one outlet of the said at least one heat exchanger to said at least one inlet of said at least one heat exchanger;
• (e) controlling a flow of coolant gas into and out of said at least one heat exchanger based on at least one condition at said at least one outlet of said heat exchanger selected from the group consisting of a flow rate of said coolant gas from said at least one outlet of said at least one heat exchanger, a concentration of impurities in said coolant gas from said at least one outlet of said at least one heat exchanger and pressure of said coolant gas from said at least one outlet of at least one heat exchanger to limit air or other gas infiltration into said at least one passageway of said at least one heat exchanger.