In other words, when valve 2 in the release cabinet is opened, CO2 reaches only after 60 to 90 seconds to the head assembly. Reasons for providing such as delay in the CO2 flooding system are given below.
- As soon as the CO2 release cabinet opens, the alarm is sounded in the protected space. A time delay gives sufficient time for any personnel in the protected space to escape, even after the operation of both valves in the release cabinet.
- If CO2 is released from the main bottles to the common manifold before opening the master valve, there may be difficulty in opening the master valve because of the bulk CO2 pressure acting on it. Because of the time delay, the positive opening of the master valve is ensured before releasing CO2.
- Regulation per International Code for Fire Safety System (FSS Code) 2.1.3.2 says, “The pre-discharge alarm can be automatically activated (e. g. by opening the release cabinet door). The alarm shall operate for the length of time needed to evacuate the space, but in no case, less than 20 seconds before the medium is released.”