Do increased-safety instruments require a safety barrier?

In principle, intrinsically safe, flameproof, and enhanced safety type instruments must be equipped with safety barriers when connected to a DCS, except for passive digital switches. It’s better to add that it only has benefits and no drawbacks for DCS.

It’s not necessary. Intrinsic safety instruments are the only ones that require safety barriers.

Upstairs, please make it clear – is it really necessary or not?

It must be selected; safety barriers come in input-type and output-type versions, and in principle, either type should be chosen

Safety barriers are used in intrinsically safe explosion-proof systems. Intrinsic safety explosion-proof system: 1. The field instruments must be intrinsically safe instruments ； 2. A safety barrier must be present on the control room side. Safety-enhanced instruments and flameproof instruments can have their signals isolated using isolators. This post was last edited by jujiangliu on 2008-1-27 20:11]

Is it really necessary? Who can give the correct answer

Inherently safer instruments do not require a safety barrier. First, it is necessary to understand the definition of increased safety: \"Increased-safety (type e) instruments do not generate sparks or dangerous temperatures that could ignite explosive mixtures under normal operating conditions. Structural measures such as sealing are taken to enhance their safety level, thereby preventing ignition under normal conditions as well as under specified overload conditions.\" Increased-safety instruments are designed with explosion protection in mind from the outset. 1: Under normal conditions, no sparks or dangerous temperatures that could ignite explosive mixtures are generated. 2: Even in the event of operational problems, intrinsically safe designs include protective measures such as sealing. There is no need to use a safety barrier anymore. And what is stated in #2, namely that \"in principle, intrinsically safe, flameproof, and enhanced safety type instruments must be equipped with safety barriers when connected to a DCS,\" is incorrect; it is probably done out of a sense of caution. The safety barrier has the functions of current limiting and voltage limiting; but who can guarantee that the intrinsically safe or increased-safety instruments connected to it will function properly? Furthermore, according to SH/T 3018-2003 \"Code for Safety Instrument Design,\" the safety instrument system should have as few intermediate links as possible, and its sensors ought to be of the flameproof type. This shows that using intermediate links in a safety system poses certain risks, as these links may fail and thereby render the entire circuit ineffective. More safety barriers are not necessarily better.

8th floor, that’s correct...........

The eighth floor made it clear: it’s not necessary. Only intrinsically safe types require safe deletion; the others do not

It’s already explosion-proof; what’s the use of a safety barrier? The same goes for Zeng An!

No, it’s not necessary; using a safety barrier with an intrinsically safe circuit is just a waste

Agreed; only intrinsically safe systems require safety barriers

Thank you, Floor 8. At first I also thought it was necessary to add safety guards, thinking it would be more secure; now I understand.

For enhanced safety, a safety barrier shouldn’t be necessary, right?:loveliness:

Except for intrinsically safe instruments, the rest do not require a safety barrier

If necessary, a signal isolator can still be added to remove noise from the signal.

I completely agree with the view from the 8th floor! !

That’s indeed the case; enhanced safety can be considered in a similar manner to explosion isolation. However, I think an isolator is still very necessary, as it ensures electrical isolation between the instruments on site and the control room, thereby guaranteeing safety

Not only is it unnecessary, but for explosion-proof instruments, the safety barrier may not be able to handle them!