A valve which is controlled using a master key such that only an authorized person is able to turn the valve on and off. The valve is constructed such that a fluid passage is controlled by rotating a handle relative to a body, including a locking device for maintaining a locked state of the handle relative to the body. A master key slot, which extends to the locking device, is formed in the handle, so that, when the master key is inserted into the master key slot, the locked state of the handle is released such that the fluid passage can be controlled by the rotation of the handle.