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!
  • Students Click Here

*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


Costing for Class I or Class II Area

Costing for Class I or Class II Area

Costing for Class I or Class II Area

Hi, I'm working on the design of two separate rooms, one is class 1 div 1, the other is class 2 div 2. Right now I'm defining the process aspects (layout, flowrates, PHA, etc), however I need to understand the cost before it gets too far along.

Does anyone know of good references for approximating the room/building cost, especially for a classified area? I've seen some guides/books on general plant costing, but I'm not sure how to add on the cost for meeting nfpa/nec standards. I've heard that controls are usually +40%, and the increase in room cost could be x2 or x3?

Thanks in advance for any help.

RE: Costing for Class I or Class II Area

The construction of the rooms are not any different between Div1 and Div2.

It's the cost of the equipment placed INSIDE those rooms that affect the cost.

So, I'm not aware of any references to costing of room/building costs.

Take a look at electrical enclosure price differences and wiring installation practices between Div 1 and Div 2 areas to get a better estimate.

This is normally the space where people post something insightful.

RE: Costing for Class I or Class II Area

Usually Class 1 wiring & devices are very costly, compared to Class 2. Generally one will try to re-classify the Class 1 room down to Class 2 if at all possible. This can be done with mechanical ventilation and gas detection (or heaven's forbid "fugitive emissions" method). Have you considered this?
If you cannot re-classify to Class 2, then try to keep as much of the electrical equipment out of the Class 1 area.

"I have not failed. I've just found 10,000 ways that won't work." Thomas Alva Edison (1847-1931)

RE: Costing for Class I or Class II Area

Get quotes from electrical contractors or you may have to develop a cost analysis by going down to an electrical supply house.

RE: Costing for Class I or Class II Area

Somebody is confused between CLASS and DIVISION or ZONE.

Class 1 means the hazard is flammable gases or vapours.

Class 2 means the hazard is flammable dusts.

DIVISION or ZONE is related to how frequently the hazard is present.

Zones 0 or 1 (Division 1) mean that the hazard is normally or frequently present. Only intrinsically safe or explosion proof equipment/instruments/lighting/wiring methods are permitted.

Division or Zone 2 mean that the hazard is only present occasionally, during an upset such as a leak etc. Nonincendive equipment is permitted, as well as anything suitable for zones 0 or 1 above.

Equipment and wiring for zone/div 2 is cheaper than for zones 0 or 1/div 1, because you have more choice of available equipment/instruments and the wiring methods are less restrictive and take less labour.

There are also temperature classes to be considered, which depend on the lowest igniting mixture that may be present.

CLASS 2 equipment just needs to be certified to be dust-tight/non igniting to dusts, which is obviously a lot easier than making something explosion-proof or nonincendive against liquids or vapours.

RE: Costing for Class I or Class II Area

Howdy Molten;
Sorry, that somebody was me. Good catch.
Perhaps Alphite (the OP) could review his original query wrt Class 1 and Class 2. (ie flammable liquids/gases vs combustible dusts).

"I have not failed. I've just found 10,000 ways that won't work." Thomas Alva Edison (1847-1931)

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!


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