×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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

Hazardous Area Classification (HAC) for Pressure Relief Valve

Hazardous Area Classification (HAC) for Pressure Relief Valve

Hazardous Area Classification (HAC) for Pressure Relief Valve

(OP)
Hi all,

Should pressure relief valve be considered as primary or secondary grade of release in IEC 60079-10-1? Section B.2.3(d) and B.2.4(d) said that relief valves can be primary or secondary depending on whether they are expected to lift during normal operation or not. My understanding is that relief valve is not expected to lift during normal operation, thus it should be secondary grade of release. We see many time that the relief valve usually have both Zone 1 and Zone 2.


According to IP-15 section 3.6.2.5, pressure relief valve is considered as secondary grade of release. To cover any fugitive emissions that may occur, a Zone 1 of nominal 1 m radius should be placed around the end of any discharge point. Where a process relief valve lifts at its design intent the extent of the resultant Zone 2 should be determined.

In summary, my conclusion is that, for relief valve, there will always be Zone 1 to cover the fugitive emission (1m or 1.5m) and Zone 2 to be determined by individual standards. Is this statement true?

RE: Hazardous Area Classification (HAC) for Pressure Relief Valve

Grades of release as defined in API RP 505 is:
Continuous : 1000 or more hours/year
Primary: 10 hours/year to 1000 hours/year
Secondary: less than 10 hours/year

In your case it appears to be an engineering judgement between Primary & Secondary.
This relates directly to Zone 1 or 2.
Even if you were to err towards the safer side and classify the area as Zone 1, would it have any effect since chances are very low you have any electrical equipment in the vicinity?
API RP 505 Fig 18 shows a 3m (10 ft) bubble of Zone 2 in adequately ventilated area.
The text reads:
8.2.3.4.1 The criteria affecting the extent of the classification of the areas around relief valve vents in nonenclosed
areas are too diverse to specify distances. Individual engineering judgment is required for specific
cases, but in no case should the classification be less than that shown by Figure 18.

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


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

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