Last week I explored when volumes of a system or portion of a system become important. Principally, volume in fire sprinkler or standpipe systems becomes important in overall capacity limitations of dry and pre-action systems and in draining portions of wet, dry, and pre-action systems. See the full article here.

This week I've created a basic quick-and-dirty volume calculator based on the length of pipe in a system (don't see the calculator below? View in your browser here): 

​​Simply select the type of pipe used and enter the approximate length of pipe for each pipe size in the system or portion of a system you're evaluating.

I created this when looking at whether I break the 5-gallon volume threshold for portions of wet sprinkler systems, bottom legs of standpipes, or overall dry and pre-action system capacities. Email suggestions or tips for improvement to me at [email protected].

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I'll be posting the weekly article tomorrow but before then I have a question and a favor.

Over the past two years I've been working on a long-awaited resource involving literally hundreds of hours of research and development, but before I wrap up the project I have just one question that will help create a better resource: Learn more and provide input with my quick one-question survey here.

It does not necessarily come up often, but the volume of a fire sprinkler system does carry several requirements.

​Dry and Preaction systems carry water delivery requirements, while all systems carry requirements for drainage. Today I'm summarizing requirements related to when volumes of fire sprinkler systems are important to consider.

Dry System Capacity

Systems under 500 gallons (1900 L):

• Not required to meet any water delivery time to inspector's test connection (NFPA 13 2002 A.7.2.3.1, 2007-2016 7.2.3.3).

Systems between 500 and 750 gallons (1900 - 2850 L):

• Not required to meet any water delivery time when a quick-opening device is provided (NFPA 13 2002 A.7.2.3.1, 2007-2016 Section 7.2.3.4).

Systems over 750 gallons (2850 L):

• Subject to water delivery times (NFPA 13 2002 11.2.3.9, 2007-2016 Table 7.2.3.6.1, below):

Hazard      No. of Remote Sprinklers Initially Open        Max. Time of Water Delivery
Dwelling Units                       1 sprinkler                                                                           15 seconds
Light                                          1 sprinkler                                                                          60 seconds
Ordinary I                                2 sprinklers                                                                        50 seconds
Ordinary II                               2 sprinklers                                                                        50 seconds
Extra I                                       4 sprinklers                                                                        45 seconds
Extra II                                      4 sprinklers                                                                        45 seconds
High Piled                               4 sprinklers                                                                         40 seconds
​

Wet System Drainage

Trapped sections of pipe less than 5 gallons (20 L):
One of the following is required (NFPA 13 2002 8.15.2.5.2.3, 2007-2016 8.16.2.5.2.3.):

• auxiliary drain with nipple and cap or plug not less than 1/2 inch in size
• removal of a single pendent sprinkler allows for drainage of the trapped section of pipe
• an auxiliary drain with flexible coupling or other easily separated connection

Trapped Sections between 5 and 50 gallons (20 - 200 L):

• Minimum 3/4-inch auxiliary drain with valve and plug or nipple and cap (NFPA 13 2002 8.15.2.5.2.2, 2007-2016 8.16.2.5.2.2). 

Trapped Sections 50 gallons (200 L) or more:

• Minimum 1-inch auxiliary drain pipe to accessible location (NFPA 13 2002 8.15.2.5.2.1, 2007-2016 8.16.2.5.2.1).
• Annex material notes that a typical accessible location would be a valve located 7 feet above floor level to which a hose could be connected to discharge water (NFPA 13 2002 A.8.15.2.5.2.1, 2007-2016 A.8.16.2.5.2.1).

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“Does this canopy need sprinklers?” “Are sprinklers required below the porte-cochere?” “I have a residential balcony; does it need sprinklers?”

​It's one of the most common design questions in commercial buildings with fire sprinkler systems; you’ve undoubtedly encountered it yourself.

The decision isn’t something that is taken lightly, either. In climates where freezing occurs, dry-sidewall sprinklers are often used for shorter-length projections. With new antifreeze systems are not an option (antifreeze must be a listed, pre-mixed solution which is not currently available), larger exterior projections could require dry sprinkler systems with increased cost, maintenance, and greater susceptibility to corrosion.
​

Good Design Judgement 

Before diving in on whether sprinklers are required or not, remember that good design judgement is always important. Just because certain code verbiage or annex material exists does not mean you, as a designer, engineer, or review authority, should forfeit good judgment or common sense. These are life safety systems and you were blessed with the ability to think analytically for good reason.

Soapbox aside; canopies, overhangs, and porte-cocheres provide a unique challenge in that they can compromise a building by (1) subjecting the building to trapped convective heat, (2) radiate heat down to the base of the fire and encourage further growth, (3) provide a continuous fuel path to the building.

NFPA 13 addresses exterior projections in Chapter 8 (2002 Edition: Section 8.14.7, 2007-2016 Editions: Section 8.15.7, 2019 Edition: 9.2.3.1 and 9.3.19.1). There are five paragraphs in this section, and while they appear straightforward there are two critical words that tend to throw a figurative wrench into every situation.

What constitutes combustible storage? Storage of any item that can burn? What about temporary placement or handling of items – would they not burn in the same fashion that long-term storage would?

While not enforceable unless specifically adopted by a jurisdiction, annex material within NFPA 13 offers guidance in interpreting what is considered “combustible storage”.

Temporary or short-term items, such as parked vehicles or delivered packages, while combustible, would not be considered ‘storage’ (NFPA 13 2007-2016 Annex A.8.15.7.2 and A.8.15.7.5, 2019 A.9.2.3.2). 

Minor amounts of combustibles may also not justify sprinklers, such as planters, newspaper machines, or combustible furniture on balconies for occupant use (NFPA 13 2002 Annex A.8.14.7.4, 2007-2016 Annex A.8.15.7.5, 2019 A.9.3.19.2). 
​

Justified Situations

Conversely, an exterior loading dock is designed to accept incoming shipments which inevitably end up residing below canopies while loading and unloading occurs, even if only temporary. While long-term storage might not occur, it could be reasonably argued that enough shipping items, pallets, boxes, or other items could collect to be considered “combustible storage”. 

Projections above the only means of egress or exterior ceilings where the building is occupied above is also suggested to require sprinklers (NFPA 13 2007-2016 Annex A.8.15.7.2, 2019 A.9.2.3.2). Either of these arrangements, if not protected, could reasonably compromise the egress ability or occupied areas above and could be justification for providing sprinklers.

Parking areas that are not used for pickup and drop-off are another example of combustibles that would be present long-term, which the annex does not exclude.
​

Judgement by the Designer and Authority Having Jurisdiction (AHJ)

If so much of the guidance is provided in the unenforceable annex material and the body of NFPA 13 is vague about combustible storage, how do we determine when sprinkler protection is required? Ultimately, the determination of whether a situation requires sprinklers due to the amount of combustible storage is up to the Authority Having Jurisdiction. It is a judgement call that is based on the amount of combustibles and length of time where combustibles would be present. 
​

An Exterior Projection Cheatsheet

While the judgement of amount of combustible storage resides with the AHJ, here is an updated and expanded flowchart based on the body and annex material of NFPA 13 to help guide the decision process (original published by the National Fire Sprinkler Association in a TechNotes in May 2007):

Congratulations to Mike, our first ever design challenge winner. 

Last week Mike's submitted "Design A" was voted the top design running away with 64% of the submitted votes. Congratulations Mike; he climbs to the top of our new leaderboard and earns a $40 gift card towards the online store.

See the submitted designs, the challenge, and follow-up discussion about them here.

Have a design challenge you'd like to propose? Send it to us at [email protected].

Which of the following designs do you prefer? 

We have two chosen finalists for this Design Challenge. Review, vote, and discuss below.

Original Design Parameters:
Codes: 2012 International Building and Fire Code
Standard: NFPA 13 - 2010 Edition
System Type: Wet Pipe System, Fully-Sprinklered
Seismic: Occupancy II, Design Category B
Construction Type: V-B (combustible)
Structure: Solid Engineered Joists
Pipe Type: CPVC or Black Steel
Surroundings: Unit door runs to the common corridor; additional units reside on each side of these units

​Design A:
[View PDFs]
​

​Design B:
​[View PDFs]
​

​What works and what doesn't? Discuss your take in the comments section on the website.

​Top designers with highest voted submissions earn a spot on our leaderboard.