Electric/pneumatic double interlocked preaction systems are commonly used as refrigerated area systems. They are also commonly used where flooding of the pipe can have serious consequences, and where it is important to control accidental water discharge due to damaged sprinkler piping. Care should be taken since double interlocked preaction systems may not produce flow from opened sprinklers as quickly as single- or non-interlocked preaction systems. Activation of the detection system alone, or operation of a sprinkler alone, will sound an alarm but will NOT cause the system to fill with water.