We periodically monitor the fall in temperature as the Gatan 914 cryo-holder is cooled in the dry pumping station. This is normally how everyone cools down the holder for use in the JEOL JEM 3200FS and knowing the rate of cooling both gives users an estimate of when the holder will be at a given temperature (so the user can time various events) and also provides us with a measure of whether anything about the holder has changed over time. The graph below shows these data over the years since the 3200FS was installed.
Rate of Cooling for the Gatan 914 Cryo-Holder
In this graph, zero marks the point at which liquid nitrogen is first introduced into the cryo-holder's dewar. We normally time events such as starting to cool the cryo-transfer station when the holder passes around -120° C and retrieving a cryo-grid from storage when the holder passes around -140° C.