Is a safety barrier required for the feedback signal of an electric control valve?
Thread Content
Everyone, does the feedback signal (analog) from the electric control valve located behind the explosion-proof area need to go through a safety barrier? If it is necessary and it is a separate safety barrier, should an operating terminal safety barrier be chosen? Please discuss it
This post was last edited by leiyu1220 on 2010-8-2 at 16:29. A safety barrier is a current-limiting circuit located between the field devices and the equipment in the control room; it serves to limit the electrical energy supplied from the control room to the field instruments, so that neither sparks sufficient to ignite hazardous gases nor surface temperatures high enough to cause such ignition can occur, thereby eliminating potential sources of explosion. When selecting a safety barrier, it is necessary to consider that its model should be compatible with the type of instruments on site. Additionally, it is important to ensure that the safety barrier is compatible with the requirements of intrinsically safe instruments, as well as to address the issue of impedance matching within the resulting intrinsically safe system. If flameproof electric valves are used on-site, no isolation barrier is required for the feedback signal ； If intrinsically safe electric valves are used on-site, a safety barrier must be installed before the feedback signal enters the control system. The safety barrier is installed in a safe area; it receives signals from the hazardous area and outputs safe signals to either the safe area or the hazardous area.
I agree with what was said above; use the operational terminal safety barrier to feed feedback back into the system
It’s not necessary; explosion-proof electric control valves do not require a safety barrier