We're working on an aircraft hanger with a foam system. I can't quite nail this down, as NFPA 409 and the UFC don't spell this out - do the hangar doors need to be open, or closed, in case of a fire or to test the foam system?

Again, don't see any guidance spelled out in either standard. Thanks in advance.

​​​​​​​​​​​​​​​​​​​​​​​​​Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

I have a project which requires a water curtain be installed on both sides of the glass due to it being the wall down a corridor.

My questions are - (1) does this type coverage require a valve and separate pipe network or can it come off the base building wet system branch lines?

Also, can these same sprinklers be used to cover the corridor as well?

NFPA-13 Section 11.3 doesn't spell this out, so I'm not sure. Thanks in advance.

​​​​​​​​​​​​​​​​​​​​​​​​​Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

I understand the limits for what is allowed, but how do you actually determine what air pressure your sprinkler systems needs to be set at?

​​​​​​​​​​​​​​​​​​​​​​​​​​Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

​ We are working on a project where the Architect is very particular about the placement of ceiling components, including sprinkler heads. The idea is to line up diffusers, lights, sprinkler heads, smoke detectors etc. The problem is, in several locations, their preferred location will place heads more than 15 feet apart. The obvious solution for him is to require the heads more than 15 feet apart to be extended coverage type.

From a practical standpoint, it doesn't make sense to scatter extended coverage heads throughout the project as it becomes an installation and maintenance (heads that down the road needing replacement may be replaced with standard coverage by mistake) nightmare.

Is there anything in the code preventing the installation of extended coverage and standard coverage heads of the same style (i.e. concealer style) in the same area?

​​​​​​​​​​​​​​​​​​​​​​​​​​Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

Is there a minimum distance requirement between a unit heater and a diesel fuel tank within a fire pump room?

​​​​​​​​​​​​​​​​​​​​​​​​​Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

When calculating a sprinkler system using the area/density method, I have heard several schools of thought:

1. All sprinklers within the remote area are to be calculated with the maximum sprinkler area coverage installed within that area (all 100 sqft, as an example).
2. Each sprinkler within the remote area can be calculated with its individual coverage area within the listing limits (94 sqft, 98 sqft, 100 sqft, etc.)
3. I have also seen, where software doesn't allow otherwise, all sprinklers within the area given an average area coverage within the calculation by adding the coverage area of each sprinkler and dividing by the number of sprinklers. 

I tend to go with the most demanding as I don't worry about bidding projects most of the time, but in short, I was wondering what the consensus was concerning validity of each of these methods.

Thanks in advance.

​​​​​​​​​​​​​​​​​​​​​​​​​​Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

NFPA 13 does not allow ESFR protection for shelf or bin box storage. I can see the logic, and this has been in the code for years.

However, FM Data Sheet 8-9 does allow ESFR protection for shelf and bin box. I can protect shelving up to 15-feet with 0.85 over 2,500 sqft but I can't protect it with K25 at 70 psi.

Any insights on the logic here? Has testing been done that supports this one way or another?

Thanks in advance.

​​​​​​​​​​​​​​​​​​​​​​​​​Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

The IBC Table 722.6.2(1) states that 1/2" gypsum has a fire resistance rating (FRR) of 15-minutes, while 3/8" OSB (the product used for TJI joist webs) is 5-minutes.

NFPA 13-2019 Section 19.3.3.1.5.2(4) Item (10) discusses an exception to hydraulically calculating the system at 3,000 sqft remote area if joist channels are firestopped into volumes not exceeding 160 cubic feet.

Most volumes created by composite wood joists are much smaller than the 160 cubic feed stated in the standard, which means that gypsum board would only be required every 4th- or 5th- joist in most situations.

However, would the 3 or 4 layers of 3/8" OSB (the web of each joist) across 3- or 4-bays meet the equivalent of the 1/2" gypsum requirement?

​​​​​​​​​​​​​​​​​​​​​​​​​Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

There's a project in our jurisdiction that is a warehouse with a detached fire pump building.

They are proposing to feed the controller for the diesel fire pump (in the detached fire pump building) from the service in the main warehouse building.

Are there any relevant fire codes or standards that require the controller to be fed from a separate service?

Or, at least fed from a service that is "dedicated" to the fire pump building?

​​​​​​​​​​​​​​​​​​​​​​​​​Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

Could anyone enlighten me on the purpose of "draft curtains" where mentioned in NFPA 409 (Standard on Aircraft Hangars)?

In particular in the context of sprinkler protection; paragraph A.5.17.3 clearly states that the reason for limiting a draft curtain area to 7,500 sqft (697 m2) is to improve detection and sprinkler response times...."

Am I right to assume that the intention is to prevent heat from a fire event from being distributed away from sprinklers above?

Would I also be right to say the same thing would apply to smoke from a fire (in respect to fire detection)?

Many thanks in advance.

​​​​​​​​​​​​​​​​​​​​​​​​​​Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

Does the requirement in NFPA 13 that “All valves controlling water supplies for sprinkler systems or portions thereof, including floor control valves, should be accessible to authorized persons during emergencies. Permanent ladders, clamped treads on risers, chain-operated hand wheels, or other accepted means should be provided where necessary” imply there is a maximum height limit for floor control valves or standpipe isolation valves?

I have a couple standpipe projects where I am having trouble squeezing in a standpipe isolation valve down low (in elevation). I haven't found a confirmation in the standard or handbook that identifies a maximum height for accessibility.

Thanks in advance.

​​​​​​​​​​​​​​​​​​​​​​​​​Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

Is it necessary to reduce the pressure serving hose connections or hose cabinets when there are the 1-1/2" or 1-inch hose connections installed in a facility?

What is the maximum allowable pressure for these type of hose connections?

Thanks in advance.

​​​​​​​​​​​​​​​​​​​​​​​​​Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

Hi everyone - I need advice about jockey pump sizing.

The system we have has a city supply plus a booster pump. The city main shut-off pressure is 42 psi (2.9 bar) and the booster pump shut off pressure is 27.5 psi (1.9 bar).

So, combined, the pressure is 69.6 psi (4.8 bar).

The jockey pump pressure should be about 10 psi (0.7 bar) higher than the booster pump pressure. So, the jockey pump shutoff pressure should be 27.5 psi + 10 psi = 37.5 psi (1.9 bar + 0.7 bar = 2.6 bar)?

Is this correct, or is the jockey pump shutoff pressure the combined 69.6 psi + 10 psi (4.8 bar + 0.7 bar)?

​Thanks in advance.

​​​​​​​​​​​​​​​​​​​​​​​​​Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

We have a project that is a 4 story residential building and within each bedroom unit there are soffits along each wall. These soffits do not exceed 24-inches.

Based on Table 12.1.11.1.4(c) in NFPA 13 (2019), it says we can neglect the obstruction and place our sidewall sprinkler off of the wall behind the obstruction.

This situation I am describing is on the top floor where we will be providing sidewall coverage instead of pendents.

My question is whether or not we can space the sprinkler as close as we want to the soffit along the wall, given it being less than 24-inches?

I'm just having a hard time figuring out if the sidewall will be able to adequately protect the space under the soffit with not much parameters.

Thanks in advance.

​​​​​​​​​​​​​​​​​​​​​​​​​Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

My client in has requested single-interlock pre-action systems be installed to protect each of their two communication / hub rooms in their new facility.

Space is limited in the facility and it was suggested to install a pre-action cabinet inside each of the rooms, thereby serving the room itself.

While a pre-action system cabinet/valve assembly cannot be installed in an area subject to freezing (application for cold/refrigerated storage) is there anything preventing the cabinet from being installed in the space it serves?

Due to dry pipe system size constraints and distance, it is not possible to locate the cabinets in the sprinkler room.

​​​​​​​​​​​​​​​​​​​​​​​​​​Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

We have been given the work to a new school, and there is a storm shelter built into it.

We want to run our pipe over head from the fire pump room, which is not storm-shelter protected, and penetrate through the storm shelter wall to protect this area. I just want to confirm if penetrating through the storm shelter wall is acceptable to do.

In the 2020 version of ICC-500, I understand it to read that penetrations shall not degrade the structural integrity and impact resistance of the storm shelter envelope. It also says that penetrations 2 ½ inches or larger in diameter should be considered openings and shall be protected in accordance with section 306.4 (impact protective systems and impact testing).

Then, reading into chapter 6, which is fire protection systems, it states: “These systems are not required to remain functional for the design storm event and minimum period of shelter occupancy (24 hours for hurricane shelters, 2 hours for tornado shelters) or to be protected from the wind load and impact requirements of Chapter 3 or flood-resistance requirements of Chapter 4.”

Is penetrating the shelter wall the best approach?

​​​​​​​​​​​​​​​​​​​​​​​​​Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

For low-pile/miscellaneous storage, NFPA 13 has Group A protection up to 5-ft in height requires Ordinary Hazard Group 2 criteria. It also requires Class IV up to 12-ft as Extra Hazard Group 1.

Could you, theoretically, design for Extra Hazard Group I, but put the Group A in the 7-12ft range with Class IV below?

There would be no commodities above the Group A plastics, but I'm not sure that the Class IV would be protected throughout properly.

​Thanks in advance.

​​​​​​​​​​​​​​​​​​​​​​​​​Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

We have a newly-installed electric (duty) fire pump, and a back-up diesel fire pump. 

Each pump has a 100% required flow capacity for the system (750 gpm each) for the building.

Is it OK to run the two pumps simultaneously during testing - which would result in a 200% flow?

The diesel pump is only intended to be used during power interruption/worst-case, but not with normal power online.

During testing, we release water in the test line (flow meter) - the pressure went down and triggered the cut-in pressure of both the electric and diesel pump which makes it run simultaneously (electric first, then the diesel a few seconds later).

Does this not have a water hammer effect on the system?

​​​​​​​​​​​​​​​​​​​​​​​​​Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

We're currently working on a school project. There's a suspended ceiling throughout much of the school. The project requires "total coverage", but I'm not sure whether this applies above the ceiling, below the ceiling, or both.

We're under NFPA 72, but 72 does not seem to clarify this either way.

Are smoke detectors required above and below ceilings, for "total coverage"?

​​​​​​​​​​​​​​​​​​​​​​​​​​Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

Off to a fresh start to the new year - thanks to our top Contributors for January 2022!

What constitutes an "accessible" vertical shaft?

We have a vertical shaft in a high-rise building, without a door at the bottom, but with windows. 

Is this "accessible" as dictated by NFPA 13?

​​​​​​​​​​​​​​​​​​​​​​​​Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe