Summary: This article explores complex fire protection issues, examining significant difficulties and solutions within fire safety regulations. Each FAQ walks you through the complexity of sprinkler installation above AHU units, pump room drainage, wet system testing in cold weather, tank requirements, and more. Valve types, HVLS fans, remote area calculations, bathroom construction, concealed spaces, water storage tanks, ESFR design areas, and fabric ducts are all covered. These practical and safe explanations unravel the intricacies of fire safety requirements. They attempt to facilitate compliance while emphasizing the essential balance between adhering to standards and addressing practical issues in a variety of settings.
Most model building and fire codes include phrases that address practical issues; here is what the International Fire Code says on the subject: “104.8 edits. Where there are practical difficulties in carrying out the provisions of this code, the fire code official shall have the authority to grant modifications for individual cases, provided that the fire code official first determines that a special individual reason makes the strict letter of this code impractical, that the modification is in accordance with the intent and purpose of this code, and that such modification does not reduce health, life, or fire safety requirements.
Installing sprinkler piping above the aforementioned AHU appears to be a practical challenge. Here are a few possibilities, though there could be others:
- Using the language above, request an exemption from installing sprinkler protection based on reasonableness and practical difficulties. A strong argument might be that the AHU is non-combustible and has no discernible fuel burden.
- Request an alternate method of compliance, such as extending the branch line outside the AHU’s border and providing sidewall or extended coverage sprinklers to spray into the area.
- Use non-combustible construction (such as gypsum or metal) to create a non-combustible concealed compartment where sprinklers are not required per NFPA 13 (2022 edition) – Section 9.2.1.2.
Floors shall be pitched for adequate drainage of escaping water away from critical equipment such as the pump, driver, controller, and so on, according to NFPA 20, 2013 edition, Section 4.12.7 for equipment protection drainage, and the pump room or pump house shall be provided with a floor drain that will discharge to a frost-free location. This is done to safeguard the pump room’s equipment from water buildup on the floor.
Section 4.11.1.4 for the circulatory relief and automated relief valve specifies that measures for discharge to a drain must be made. Although this is the most common application in the field, it is not required to drain to the floor drain. The circulation relief valve could discharge to a drain other than the necessary floor drain in Section 4.12.7.
NFPA 241, Standard for Safeguarding Construction, Alteration, and Demolition Operations, may also provide further guidelines while the facility is being built. This standard specifies fire protection procedures for building construction. The owner must create a fire prevention program that addresses the challenges associated with providing fire protection, such as sprinkler systems in new buildings. An outline of this fire prevention program can be found in Section 4.2.2 of the 2022 edition of NFPA 241.
Section 4.3.2 of this standard discusses the fire sprinkler system requirements for the given situation.
Yes, a vented water tank for fire protection is required. This is covered in NFPA 22, 2023 edition, Section 4.15 for roof vents, as well as Chapters 5-13 depending on the type of tank used.
A high-volume low speed fan is defined in NFPA 13, 2016 edition, Section 3.3.14 as a ceiling fan having a diameter of 6 to 24 feet and a rotational speed of 30 to 70 revolutions per minute.
Based on this description, your 8-foot-diameter fan would meet the requirement if the fan speed is between 30 and 70 revolutions per minute.
Section 11.1.7 for design approach and high-volume low speed fans specifies that HVLS fans installed in buildings equipped with sprinklers, including ESFR sprinklers, must be centered approximately between four adjacent sprinklers. There is no exception to this requirement in the standard.
In this situation, Section 11.1.7 would be applicable to center the fan approximately between the four neighboring sprinklers, assuming the fan fulfills the definition of a high-volume low-speed fan stated in Section 3.3.14. It is possible that the fan speed does not fulfill the definition.
The test data reports are referred to in Annex Section A.11.1.7. As permitted by Section 1.5, it may be possible to analyze these reports and produce an equivalent design. The specification appears to be intended to center the fan to have the least influence on both sprinkler activation time and impediment to sprinkler pattern creation.
Section 11.2.3.2.3.1 of NFPA 13, 2013 edition, provides for quick response area reduction for a system or section of a system with the same hydraulic design foundation.
The standard’s aim, as stated in Section 23.4.4 for hydraulic calculation processes and the area density approach, is to employ the design area that generates the greatest amount of hydraulic demand. This might be the area with the 9 foot 6 inch ceiling or the area with the 12 foot 8 inch ceiling height in this scenario, using quick response sprinklers and the permissible area reduction based on ceiling height.
To ensure that the system is calculated to the highest hydraulic demand, the conservative approach would be to provide hydraulic calculations for the entire system based on the higher ceiling height of 12 foot 8 inches, or separate hydraulic calculations could be performed for each portion of the system with different ceiling heights and different hydraulic design areas.
- The bathroom cannot be larger than 55 square feet.
- Walls and ceilings are noncombustible or limited combustible, and
- Walls and ceilings, including those behind any shower enclosure or tub, have a minimum thermal barrier value of 15 minutes.
Gypsum, sometimes known as drywall, is classified as a limited combustible material. The thickness of 5/8 inch will meet the 15-minute thermal barrier criterion.
It is critical to note that Section 9.2.4.1.1 only applies to bathrooms in dwelling units. It should also be noted that sprinklers are necessary even if Section 9.2.4.1.1 is met if the restrooms are in a limited care facility or nursing home (as defined in NFPA 101), or if the bathroom(s) open immediately to a public hallway or escape way.
Sprinklers are not required in concealed compartments that “… are not used or intended for living purposes,” according to NFPA 13D (2019) Section 8.3.5.
Even with the access panel, this space is not meant for residential purposes; therefore, sprinkler protection is not required.
The 2018 edition of NFPA 22 has no universal requirement for all equipment to be included. Section 14.4 specifies the tank fill requirements but does not need the fill valve and mechanism to be mentioned.
If the tank is a break tank, however, the refill mechanism must be listed. Section 3.3.2.2 defines a break tank as a tank that provides suction to a fire pump whose capacity is less than the fire protection demand (flow rate times flow duration). You have specified that this is not the case in your case. Section 14.5.2 applies only to break tanks and requires the filling mechanism to be specified and set up for automatic operation.
The goal of this 768 square feet minimum design area is to prevent a greater number of sprinklers from being activated in a fire situation where 12 closely spaced sprinklers cover a limited floor area.
In summary, even with the reduced spacing allowable in the NFPA 13 2022 edition for ESFR, the minimum of 12 sprinklers and 768 square feet of design area must be satisfied.
Section 9.5.5.3.2 states that sprinklers are not necessary beneath barriers that are “not fixed in place.” This area, on the other hand, is intended for objects such as tables and other moveable furniture. Because the duct is part of a fixed construction system, it is not movable and would still present an impediment when inflated, so it should be handled as such.
The installation committee recently reviewed this matter informally, and the opinion was that these fabric ducts should be classified as impediments (when they are wider than 4 feet when inflated). Many of these fabric ducts also have a strong frame and will not collapse when not in use.
Courtesy: Roland Asp, CET, TechNotes
