×
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

Fire water demand and pressure

Fire water demand and pressure

Fire water demand and pressure

(OP)
Can anyone help me estimate the fire water demand and pressure required for an office building. We need this info as preliminary interface data for utility requirement.

Any information is highly appreciated.

Thanks.

RE: Fire water demand and pressure

If it is just simply an office building with ceilings <10', metal building and no storage, wet pipe system & quick response sprinklers, the flow could be as low as 100 gpm interior demand and a hose allowance of 100 gpm.

If you have a wood structure with slopes >=4:12, you could have a demand of 500+ gpm interior and 100 gpm hose allowance.


The pressures could be as low as 25 psi at the base of the riser for the wet system and around 50 psi at the base of the riser for the dry system.  All of the pressures can be modified with pipe sizing.

So, as you can see, more information is needed to get what you want.

RE: Fire water demand and pressure

(OP)
Thanks TravisMack,your info is helpful but we would like to provide maximum values for gpm and pressure because this is for conceptual study so, I think the maximum is better.

Please consider the building as a 3-storey, Security building with an armory section. Would the armory room would affect the water demand and pressure?

I have read from a fire pro reference that the maximum gpm for Ordinary hazard application based on Pipe schedul is 1500 gpm and the maximum pressure for fire pro sysytem is 95 psi. I just would like to hear some comments from experienced people on this.

Any info is appreciated.

Thanks.

RE: Fire water demand and pressure

Stored ammunition is a Class IV commodity.  Being a 3 story building, I would assume that your storage for the ammunition would be less than 10' in height.  Therefore, you could be at Ord Grp II requirements.  For a wet system, you could be at a minimum of 300 gpm + 250 gpm hose allowance.  Practically, you can figure about 15% overdischarge from the sprinkler system and have 330 gpm + 250 for a total of 580 gpm.  Pressures are all dependent on the pipe sizing and sprinklers chosen.  You could probably get by with 50 psi or so at the base of the riser.

Don't even consider pipe schedule stuff for you application.  It is very likely that you would not be allowed anything with a pipe schedule and would require a calculated system.

Good luck!!

RE: Fire water demand and pressure

(OP)
Thanks again Travismack, I have specified 750 gpm and 95 psi. I included some allowance since this are assumed values and they are subject to change during detailed design.

What would be the size of the main FW pipe for the above specs?

Thanks.

RE: Fire water demand and pressure

You could likely bring that in with a 6" line, depending on how far you have to run the fire line from the city tap.

RE: Fire water demand and pressure

(OP)
Thanks TravisMack for being helpful and sharing your thoughts.

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