LAG time is the difference of temperature (121.10C) reached on first sensor to last sensor.
LAG time is the time required to reach the temperature 1210C from first sensor to last sensor. LAG time may be 1 minute,2 minute or more.
LAG time is calculated at time of heat penetration study.
The time between when the drain has reached the sterilization temperature and coldest part of your load reaches it is the equilibration time .
EN 285 states that for autoclave chamber upto 800 liter, the equivalent time should not exceeds15 second. For larger chambers it should not exceed 30 second.