In a deluge sprinkler system, what condition applies to the sprinkler heads under normal conditions?

In a deluge sprinkler system, the key characteristic is that the sprinkler heads are open at all times and there is no water in the piping under normal conditions. This design allows for immediate discharge of water over a large area when activated, typically responding to fire detection. Since the sprinkler heads are always in the open position, there is no risk of water pooling or static pressure in the pipes until a fire is detected, which triggers the system. This setup is particularly effective in environments where rapid and widespread cooling of the fire is necessary, such as warehouses, aircraft hangars, or anywhere large open spaces exist.

In contrast to the other choices, which suggest different conditions for the status of the sprinkler heads or water in the system, option A correctly encapsulates the operational function of deluge systems, highlighting that they are designed for immediate activation rather than holding water under pressure in normal conditions.