Attached are the pressure trends related to the CP4 from the past two days.  Keep in mind that much experimenting was taking place during this time frame as we sought to understand our bake-out system so PT245's erratic behavior isn't surprising.  Rather, the correlation to PT210 absent a correlation with PT246B is what has me scratching my head.  

I didn't make any changes to the regeneration parameters but did notice when standing outside by the flow meter and exhaust outlet that there was some cyclical surging of flow between 25-40 SCFH which could be heard in the exiting exhaust that I hadn't noticed before.  Also, that more of the radiator sections of the ambient-air vaporizer were frosted than had been earlier.  I am surprised that CP4's exhaust pressure indicates 0.0 PSIG with so much flow.  

Note the increase in LN2 consumption (see attached graph) as the result of regenerating CP4