The invention relates to a valve for pipelines of firefighting systems, comprising a supply line (32) for extinguishing fluid that is held at an excess pressure, a drain line (34) for the extinguishing fluid with locking elements (36, 46) that are located between the supply line (32) and the drain line (34) and with an actuating element (38) that operates the locking elements (36, 46), displacingthe latter (36, 46) into an open position and a closed position. In the resting state, the locking elements (36, 46) are in the closed position and in the event of a fire, the actuating elements (38)displace the locking elements (36, 46) from the closed position into the open position, in such a way that extinguishing fluid flows from the supply line (32) into the drain line (34). To carry out maintenance without the loss of extinguishing fluid, the locking elements (36, 46) are configured by means of the actuating elements (38) in such a way that during a maintenance operation, the locking elements (36, 46) can be displaced from their closed position to prevent the extinguishing fluid from flowing from the supply line (32) into the drain line (34) during said maintenance operation.