I have noticed an excessive amount of flow exhausting out of CP4's dewar (a.k.a. vertical storage tank #8514372) this week (earlier too?).  The indicated vapor pressure between the two mechanical gauges range between 5 < vapor pressure < 10 psi which is on the "low side" of normal for this tank -> By kicking the piping in order to liberate the accumulated frost and gain access to the economizer valve's pressure adjusting screw I caused the flow to stop.  No adjustment was needed - valve was just stuck open.  This used to happen frequently during freezing weather because these valves (actually function only as adjustable pressure regulating valves) were originally installed with the adjusting screw pointing up.  Water would get inside the valve body via the screw's parallel threads and, when frozen, would lock the diaphragm and prevent it from deflecting.  However, most of these (including this one) had long ago been rotated so as to point down.  Don't know why this one was stuck.