Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

What is difference between "identical or diverse separation"

What is difference between "identical or diverse separation"

What is difference between "identical or diverse separation"

in ISA 84.01 standard,

sensor section:

"B 1.5.3 For SIL 3, identical or diverse separation between BPCS and SIS is typically needed to meet the required safety integrity."

But I don't understand what is difference between "identical or diverse separation"

Anyone can tell me? I'll appreciate your reply.

RE: What is difference between "identical or diverse separation"

Identical means using the same technology for both the BPCS and the SIS. Diverse means using different technologies from the same manufacturer or technologies from two different manufacturers. Separation generally means physical separation, i.e., the same instrument/actuator/logic solver/wiring is not used for both the BPCS and the SIS.

Diverse separation helps reduce common failures and systematic faults in addition to reducing random failures. Because the components are the same in identical separation, common or systematic faults may affect the performance of both the BPCS and the SIS.

By the way, it would probably be better to post this in forum196: ISA (control systems engineering) Code Issues.

"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.

RE: What is difference between "identical or diverse separation"


Thank you very much!
Your explanation is very detailed and convincing.
Also you are very kind.
I'm newcomer ,not familiar with forums here.
But I think Eng-Tips is very good forum, I'm luck to meet Eng-Tips and you!

RE: What is difference between "identical or diverse separation"

Little activity exists in the ISA forum.  This is as good a place as any for the topic.

xnuke described the situation well.  Perhaps some companies want to use the same hardware for BPCS and SIS.  However different technologies are recommended to reduce the common mode issues.  This applies to different measurement technologies too.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close