Intrinsic safety instruments are connected to a safety barrier

The safety barrier is a key instrument that ensures process control systems have safe spark explosion-proof properties; it must be installed in the control room as a device that connects the instruments and devices in the control room with those on-site. On one hand, it serves to transmit signals； On the other hand, it is also used to restrict energy from entering dangerous areas. The safety barriers currently in use mainly fall into four categories: oil-resistive, Zener-type, relay-amplification type, and isolation-type. Among them, the Zener-type and isolation-type safety barriers are the most commonly used.

Prevent energy from the control room from being transmitted to hazardous areas through instrument cables.

Who said it’s necessary? For safety barriers, there’s no rule specifying which type of gauge must be used. It’s all based on the user’s needs! It just usually needs to be paired! Safety, safety first! ! ! !

Intrinsic safety can only be achieved by connecting a safety barrier; therefore, only instruments connected to a safety barrier can be considered intrinsically safe instruments.

To form this safety circuit, it is necessary to add components; current and voltage limits are enforced through safety barriers to ensure the safety of the entire circuit.

In theory, all instruments should specify which safety barrier, in combination with which parameter, is required to achieve a certain level of protection

Thank you all. Both safety barriers and intrinsically safe instruments serve to limit energy output. As mentioned on the 4th floor, intrinsically safe instruments can function whether or not a safety barrier is used. I have a question: For intrinsically safe instruments equipped with safety barriers, the instrument signal still meets the requirements after going through two levels of signal attenuation. However, for flameproof instruments used in the field, it’s not necessary to use safety barriers. But if a safety barrier is still used, will the instrument signal fail to meet the requirements after those two levels of attenuation?

There are many instruments that are both flameproof and intrinsically safe. Appropriate solutions are provided based on the user’s situation. For example, a transmitter can function in dIICT6 mode as well as iaIICT4 mode. If the user believes that dII is sufficient, then it isn’t necessary to use a safety barrier; however, if the overall system requires ia mode, then a safety barrier must be used.

This post was last edited by qugd on 2015-12-9 at 12:37. Intrinsic safety refers to the entire circuit system, not just a single component. To achieve the intrinsically safe explosion-proof level, in addition to the instrument itself having an intrinsically safe certification, it also needs to be used in conjunction with a safety barrier. Someone mentioned above that a safety barrier can be used or not in an intrinsically safe circuit; this shows a complete lack of understanding of the true meaning of intrinsically safety. If an intrinsically safe instrument is not explosion-proof at all when no safety barrier is used, it is because limiting the current in the circuit with a safety barrier is a prerequisite for achieving the intrinsically safe level. An intrinsically safe circuit requires a safety barrier, intrinsically safe instruments, and intrinsically safe cables. For specific detailed requirements regarding intrinsically safe circuits, reference can be made to the national standards for specifications on intrinsically safe explosion protection.

Agree with what was said above. Intrinsic safety refers to a circuit that includes instruments and wiring. Intrinsic safety instruments only ensure the safety of the instrument itself, not the wiring. On Intrinsic Safety instruments, sparks can be generated if the circuit is short-circuited or grounded during wiring. The safety barrier limits the power of the circuit. The goal can only be achieved by ensuring that all components in the circuit are intrinsically safe. Some projects make extensive use of flameproof instruments, which reduces the number of instrument components and improves their reliability. As long as it is not in Zone 1, intrinsically safe instruments are not required; flameproof instruments should be used instead.