One of the keys to ensuring that a sprinkler system will be fully operational when needed is to provide supervision of the conditions that are essential for the proper operation of the sprinkler system. Along with periodic testing and maintenance according to applicable standards, knowing that all the valves that control the flow of water to any portion of the sprinkler system or water flow device is the best way to make sure everything will operate as expected. All of the control, test, and drain valves on a sprinkler system should have a permanent sign attached to them that describes their function and states whether they should be open or closed. These signs are required by NFPA13, 1999 3-8.3 and are available from most sprinkler distributors.