According to Japan’s “Machinist Shim bun” report, in response to the nuclear sewage leakage accident at the Fukuyama Chichi Nuclear Power Plant on February 7, Tokyo Electric Power Company announced the results of its investigation on February 15, saying that the leak was caused by staff not closing the manual valve.
Manual valves usually open and close without feedback signals. Например, we commonly use manual stop valves, manual gate valves and other products. It opens or closes the general on-site valve identification plate, normally open, normally closed, etc.Unlike pneumatic valves and electric valves, which generally have a travel switch. Through the action of the valve stem of the on-site valve, the contact of the travel switch is driven to close or open, and the feedback signal is sent to the control room. The control room can judge the switching status of the on-site valve through feedback signals.
Следователно, manual valves in important occasions must also be equipped with travel switches to feed back signals to the control room. Например, signal butterfly valves and signal gate valves in fire protection systems.
The signal butterfly valve is a manual elastic sealing butterfly valve with a signal device at the switch position. В общи линии, center line soft sealing butterfly valve or double eccentric butterfly valve is used.The connection methods include flange connection, clamp connection and clamp connection. The driving method generally adopts worm gear drive or handle drive.There are generally two micro switches for signal butterfly valves. One outputs a signal when turned on and one outputs a signal when turned off.
Тhe signal gate valves are generally concealed-stem elastic seated gate valves with a signaling device installed at the valve stem. By turning the hand wheel, the signaling device gear is driven and the micro switch is triggered to send a signal.
In actual work, according to the importance of the impact of the medium in the pipeline on the production process, manual valves can be equipped with travel switches. It is very necessary to know the on-site valve switching status in real time.