Is there a standard spacing for private fire hydrants?

No applicable code for this project, but looking for guidance in what would be common under NFPA 24, NFPA 1 / 101, and/or the IBC. Thanks in advance.

​​​​​​​​​​​​​​Submitted anonymously and posted for discussion. Discuss This | Submit Your Question | Subscribe

What is the residual pressure and flow require for both public and private fire hydrants?

​​​​​​​​​​​​​​Submitted anonymously and posted for discussion. Discuss This | Submit Your Question | Subscribe

Many sprinkler systems in our area (I'm a fire marshal) have aboveground pipe installed by a fire sprinkler installer and the underground installed by an underground pipe contractor. NFPA 24 requires a minimum flow rate from underground pipe in order to remove rock and debris from the underground pipe.

Many of the underground contractors simply open up the pipe and wait until there's consistent clear water and/or stop hearing the rocks ping around. There's no measurements taken for the underground flushing and when I ask for them to verify the flow rate I get blank stares.

Is there a way to tell just by static pressure in the area if opening up the pipe flange is enough flow to satisfy the underground flushing? Or is there a measurement I should be seeing to verify the flow rate? 

Thanks in advance.

​​​​​​​​Submitted anonymously and posted for discussion. Discuss This | Submit Your Question | Subscribe

NFPA 24, Section 7.1.1.2 (2016 Edition), states that control valve shall be installed in each hydrant connection.

What is the purpose of this control valve, other than facilitating maintenance?

Would this be considered a "control valve" per NFPA 24 3.3.3, and does this have to be a post-indicating type valve?

Please can someone give some information regarding the filling speed of a empty pipeline to a sprinkler line?

In my case there was water hammer in a 6” line, The 16” firewater line was under 175 psi pressure and the opening time was 9 seconds.

Is 3 feet per second more realistic? Or is there a NFPA standard that addresses this? Thanks in advance for your support!

​​​​​​Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe

Have a project which has a remote fire department connection outside of the main building. The fire department connection has its own dedicated feed that goes from the remote FDC, underground, up into the building, where it connects to the fire sprinkler riser downstream of the backflow preventer.

The check valve for this line is required to be inside the building, so the main between the FDC and check valve in the building is intended to be dry.

NFPA 24 (if that applies) allows PVC for underground water service in its table of permitted pipe types.

NFPA 13 specifically states that galvanized steel is permitted to be used between the FDC and the check valve serving the FDC. I can't see where NFPA 13 would mandate pipe types for this arrangement.

Is this underground FDC feed allowed to be PVC?

​Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe

I haven't had any experience doing site calculations before, but I'm curious how it works from a practical standpoint. Fire Flow is required by the International Fire Code here locally, and there's guidance (albeit not formally adopted) in Appendix B of the IFC for a total demand. Additionally, there's hydrant spacing requirements for any particular building, and guidance on how far the hydrants can be from a building.

In order to determine how the hydrants are fed (dead-end vs. looped and size of pipe), are there specific flow and pressure amounts that each hydrant has to be calculated at?

Is it similar to a standpipe calculations where each hydrant has to have a specific flow?

I'm not performing the design work myself, but I'm just curious how that is typically done and pipe size determined.

​Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe

I have a project that is Seismic Design Category D. I'm researching and I thought there were requirements that stemmed from the Northridge Earthquake in 1994 related to the limiting the height/length of the sprinkler service entry.

Is there a 5-foot limit from the underground to the riser for seismic projects?

​​​​​​​​​​​Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe​

What is the best way to cut in to an existing underground line that may have a thrust block at the end?

We are doing a project that has scope to retrofit an 8" backflow into an existing approximately 200' of 8" underground. There is an existing detector check valve in the line which will be removed. Because of the age of the building and underground (about 30 years old) it is assumed the piping has a thrust block at the end. But with cutting into the line and adding a couple 90 degree elbows to get the backflow above ground there is fear that the line may slip back to the water main because the thrust block at the end of the 200' run is no longer holding the entire line in place.

We are planning to add a thrust block to the new 90s, but the issue is that there is only a shut off valve that is in the straight line of the 200' of pipe. If we shut that valve, there will still be pressure on the front side of the valve and when we cut into the pipe, the pipe may slip.

Any suggestions on securing the pipe on the supply side of the new backflow or limiting the pressure prior to the concrete being poured on the elbows for the backflow?

​​​​​​​​Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe

One of the frustrating non real-world things in consulting is that on the contracting side, 99.9% of the time we start at flange inside the building. Red-line the contract if needed, or work out an informal deal with the underground contractor. 

On the consulting/engineering side we have this whole underground spec section, just for five-feet out, including tracing wire and tape, testing offsite soils, soils disposal, shoring, compaction, size of rock, etc.  I understand the civil engineers will only take it to five feet. 

I’ve asked my people why we can't just match reality and just start inside the building? I am told if we did there is this 5-ft. gap that has to be claimed by someone (despite what is done in reality).

Have you addressed this in your experience in any way? I am wondering how others deal with it. On the contracting side we all just made it happen.  On the consulting/paperwork side, it’s hard to make the paperwork match reality.  Do you even seen thrust block calcs submitted from anyone since it is part of the imaginary five-feet out?

Sorry, ranting a bit, it came to mind again today because I have constructability comments from the architect that recognized that in this particular case, the AHJ permit covers from the flange, their solution is to have my spec cover the entire fire line. I’m not comfortable with that.   

​​​Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe

Do underground gate valves for fire main water supplies have to be monitored and supervised?

​​​Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe

For straight pipe couplings, are thrust blocks required, or is it only at any change of direction in the piping? It seems as though restrained joints seem to be common now, but the question came up when using thrust blocks instead of the restrained joints.

Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe