A vacuum jacketed probe adapter for connecting to a cryogenic liquid pipeline probe, wherein said probe includes a sample take-off line, a cryogenic valve and a vacuum port connection, said adapter characterized by: a) a flange member of a select length and first cross-section dimension adapted to overlie and enclose the cryogenic liquid pipeline probe and hermetically seal the cryogenic liquid pipeline probe from an ambient environment; b) a first length of hollow vacuum tubing with a first end and a second end, having a cross-sectional dimension corresponding to that of the flange member to be hermetically sealable thereto at said first end and projecting from said flange member; c) a valve housing defining a chamber and at least a first, second and third entry ports spaced from the cryogenic liquid pipeline probe, said valve housing being hermetically sealed to the second end of the first length of hollow vacuum tubing at said first entry port, said second entry port having a sealable door for access to the interior of the valve housing, said valve housing enclosing a first cryogenic venting bleed valve and a second cryogenic blocking valve, said cryogenic bleed and blocking valves being accessible through said second entry port; d) a sample take-off line for transmitting a cryogenic liquid sample from the cryogenic liquid pipeline probe, extending centrally through the first length of hollow vacuum tubing, said take-off line connectable to the cryogenic liquid pipeline probe and projecting into said valve housing, said sample take-off line being connected to said first cryogenic venting bleed valve and then exiting the valve housing from said a second cryogenic blocking valve through said third entry port; e) a second length of hollow vacuum tubing with a first end and a second end, hermetically connected to said third entry port at said first end of said second length of hollow vacuum tubing, said sample take-off line being disposed within and extending centrally through said second length of hollow vacuum tubing; and f) a connector in said take-off line formed proximate to the second end of said second length of hollow vacuum tubing to feed the content of the take-off sample into a vaporizer cabinet. a) a flange member of a select length and first cross-section dimension adapted to overlie and enclose the cryogenic liquid pipeline probe and hermetically seal the cryogenic liquid pipeline probe from an ambient environment; b) a first length of hollow vacuum tubing with a first end and a second end, having a cross-sectional dimension corresponding to that of the flange member to be hermetically sealable thereto at said first end and projecting from said flange member; c) a valve housing defining a chamber and at least a first, second and third entry ports spaced from the cryogenic liquid pipeline probe, said valve housing being hermetically sealed to the second end of the first length of hollow vacuum tubing at said first entry port, said second entry port having a sealable door for access to the interior of the valve housing, said valve housing enclosing a first cryogenic venting bleed valve and a second cryogenic blocking valve, said cryogenic bleed and blocking valves being accessible through said second entry port; d) a sample take-off line for transmitting a cryogenic liquid sample from the cryogenic liquid pipeline probe, extending centrally through the first length of hollow vacuum tubing, said take-off line connectable to the cryogenic liquid pipeline probe and projecting into said valve housing, said sample take-off line being connected to said first cryogenic venting bleed valve and then exiting the valve housing from said a second cryogenic blocking valve through said third entry port; e) a second length of hollow vacuum tubing with a first end and a second end, hermetically connected to said third entry port at said first end of said second length of hollow vacuum tubing, said sample take-off line being disposed within and extending centrally through said second length of hollow vacuum tubing; and f) a connector in said take-off line formed proximate to the second end of said second length of hollow vacuum tubing to feed the content of the take-off sample into a vaporizer cabinet.