Many years ago but I had supervised and installed several IRCD doors. I very well may be wrong but the DP system only releases the ballistic panels to allow for airflow as to not hurt the crew or create further damage to the door. The door remains locked but provides a lesser degree of security. At interval and initial installation the door is tested by applying vacuum pressure to a sensor/ pneumatic/mechanical device on the door. Logically I believe it is on the inside, have not really payed much attention to them since mandated installation.