John W. observed that actuating GV18 for 4 minutes and 18 seconds did not hard-close the valve, i.e. is a good value to use for soft-closing GV18.  

History:  The individual actuation times resulting in a hard closure of the beam-tube valves (electric) was observed and recorded early on.  This value is used to determine the actuation time to soft-close a given (electric) beam-tube valve.  We are now wanting to record the actuation times of all of the electric valves.