Proper Use of Cold Traps

In addition to more efficient throughput, the trap arrangement on the right of Fig. 7.31 allows one to remove the condensate while frozen. This helps prevent the condensate from drifting back into the system after it has defrosted, and if there are any particularly dangerous materials, they can be moved to a fume hood for dealing with in a safe manner. 

There is an argument in favor of the design on the left of Fig. 7.31 If there is poor trap maintenance, and the frozen vapors defrost (and collect on the bottom of the trap), there is no chance for these liquids to be sucked into the pumps by someone throwing a switch or stopcock at the wrong time. However, for this amount of liquid to reach the level of the inside tube indicates poor trap maintenance. In addition, this amount of condensate had to have effected gas transport. 

TAb Prevent oil back-streaming irir iririr iririr N/R irir iririr iririr irir irir ir N/R N/R N/R 

TMC Time interval to replace elements Six months Six months Vapor load Vapor load Load 7 Vapor load Vapor load - - - - - 

TC4 Trapping mech. operating temperature Room temp. Room temp. Room temp. Room temp. Room temp. Room temp. Room temp. 198° C 79° C 1 to 20° c Room temp. Room temp. 

---