Maintenance of Cold Traps

There are two types of cold trap maintenance (1) maintaining the liquid nitrogen (or the coolant of choice) at a proper level while the trap is in use and (2) maintaining clean traps to ensure the best throughput. 

Maintenance of Liquid Nitrogen. A variety of automatic filling devices have been designed to maintain the liquid nitrogen level within a Dewar. Many of these 

T In a study by Brown, it was found that white protective wrapping tape made a small, but noticeable, difference in how long liquid nitrogen would remain in a Dewar as opposed to no tape or black electrical tape. 

Incidentally, if your work creates a constant buildup of material in the cold traps, have extra trap bottoms available. This preparation allows you to remove a filled trap bottom and transfer it to a fume hood while immediately replacing another on your vacuum line, thus significantly cutting down the amount of downtime on your system. 

Following Fig. 7.34, if you need to temporarily remove the base of a trap while a system is in use  

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