×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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

Jobs

sizing the vent line for hydrogen gas prv

sizing the vent line for hydrogen gas prv

sizing the vent line for hydrogen gas prv

(OP)
Hi,
First time poster here and I'm not sure how much information to provide.

I am designing a vent line (to atmosphere) for a small compressed hydrogen fueling station. One of the only codes that addresses hydrogen stations (International Fire Code, Section 2209 Hydrogen Motor Fuel-Dispensing and Generation Facilities) states that the vent piping shall be designed for the maximum back pressure within the pipe..
and the vent pipe flow rate shall be sized IAW CGA 1.3 for a non-engulfing fire ...in this case...only 3 cfm (the electrolyzer and compressor are small).

Is the maximum back pressure in the pipe, essentially the storage pressure (MAWP of 6667 psig) minus the pressure drop across the RV
or
can the back pressure be calculated using Leq, f, Re and other parameters?
(the vent line is 15 ft long) (If so, what method/equations are appropriate?)

I plan on using a 1" SS pipe (same as PRV outlet), but I'm not sure what schedule is required.

Thanks for your help

RE: sizing the vent line for hydrogen gas prv

Binginch  Referring to  formula page
http://www.chemengsoftware.com/ventheader/formulas.htm


The formula for "definitive pipe sizing" for G has a typo and for isothermal flow is messy to work with.
The radical should contain a "difference   P1^2-p2^2

why calculate r2 and P2 since for isothermal flow r2/p2= R/T2 and T is presumably known.

I have not checked out the constant in that equation.

RE: sizing the vent line for hydrogen gas prv

Hello,

In addition to that you might look at the NASA Glenn RC Safety Manual to address other issues.  Specifically, look at Chapter 6 regarding Hydrogen:

www.nfpa.org/assets/files/PDF/CodesStandards/HCGNASAHydrogenCh06.pdf

And specifically 6.5.8. for STV issues. NASA has much experience in handling hydrogen and "lessons learned" have found their way to the Safety Manuals.

ASME is currently working on a new B31 Code for Pressure Piping, B31.12, Hydrogen Piping.  Watch for the first issuance.

Regards, John.

RE: sizing the vent line for hydrogen gas prv


why calculate r2 and P2 since for isothermal flow r2/p2= R/T2 and T is presumably known.
CORRECTION TO ABOVE
r2/p2= 1/(RT)

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!


Resources