This article is part two of a three-part series:
- Click here to read part one
- Click here to read part three
Introduction
During the design phase of a project, the sprinkler designer will go through several steps. These steps may vary depending on the specifics of the project, or the order may change due to the individual designer’s methods.
1. Consult with the building owner/client.
It is normally best to start with a meeting with the client to determine a clear scope of work. Some of the following steps may be affected or even added/removed based on the clarification of the client’s needs. Example scenarios of this include moving or lowering the height of storage, or the client may want to strengthen what they already have in anticipation of the building’s occupancy changing in the future.
2. Analyze the water supply.
The designer will perform one or multiple flow tests in order to determine the water supply that will feed the sprinkler system. Sometimes a water model can replace a flow test. The testing of the hydrants must adhere to NFPA 291 requirements. The flow test is performed by opening a fire hydrant and measuring the resulting water flow with a pitot tube. Static (no flow) pressure and residual (flowing) pressure are measured by placing a gauge on another hydrant to measure both. The designer sometimes performs this test, but sometimes a third party may perform the test.
3. Determine applicable codes and standards.
A conversation with the local AHJ or referring to the city’s website can define the local codes and standards. They can vary based on the authority having jurisdiction’s preference, geographic area, and sometimes by the property insurer.
4. Identify the hazard or commodity.
The hazard or commodity will dictate the type of sprinkler system needed, and it will also be critical to determine the correct density for hydraulic calculations later on.
5. Identify the sprinkler system type.
Based on the steps taken so far, the designer should be able to determine the type of sprinkler system that will best serve the application. There are system types for specific commodities, building types, and weather conditions.
6. Lay out the sprinklers and system piping.
After the designer has gathered all of the above information, they can begin laying out the sprinklers. The design must follow NFPA 13, manufacturers’ data sheets, and any local codes or amendments in the sprinkler layout phase, as well as throughout the design process. From this sprinkler layout, the designer will lay out the system piping, connecting the heads to the feed mains with branch lines and routing around obstacles in the most hydraulically efficient manner.
7. Perform the hydraulic calculations.
Once the designer has laid the system out, they must verify it with hydraulic calculations utilizing the water source that they evaluated earlier. The designer will calculate the most hydraulically demanding area of the system to a predetermined density (volume of water over area), as dictated by code, based on the hazard. The results of these calculations will determine if the water supply is adequate to support the system. If the supply is insufficient, the designer can upsize the piping or add a water tank/fire pump. A fire pump will aid the water supply if a lack of pressure is the issue, and a tank will supply water if volume is the issue.
8. Obtain authority having jurisdiction (AHJ) approval of the designs.
The local authority having jurisdiction must review and approve the design once it is complete. The designer may need to make adjustments and corrections based on this review.
9. Prepare for system installation.
Next is the stock listing step, which is the process of selecting the materials required for fabrication based on the design plans. System components will be ordered based on the list of materials created from the stock listing. The system will then be fabricated and installed. Sometimes a third party will complete the stock listing and fabrication, but the designer will typically answer questions and provide support during this phase.
10. Await system inspection and final approval.
After the system installation, the AHJ performs an inspection. The designer normally answers questions pertaining to system design or design alterations to meet the AHJ’s comments.
Factors to Consider in the Design
When a designer begins a project, they must consider the following factors.
- Building Layout: size, exit door location, presence of large openings, etc.
- Building Occupancy and Use: warehouses, data centers, etc., all have different sprinkler needs
- Local Codes and Standards: NFPA 13 and other AHJ requirements
- Geographic Area: areas subject to earthquakes may need seismic bracing, and buildings that are in freezing temperatures may require dry sprinkler systems
Become a Designer at Telgian Engineering & Consulting (TEC)!
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About the Author
Jacob Ford, Discipline Team Leader, Fire Suppression Design
Jacob Ford is the Team Lead for Telgian Engineering & Consulting’s Fire Sprinkler Design Team. He started his career as an apprentice pipefitter, then moved into a designer role shortly after college, and has been in the industry for nearly 20 years. Jacob has worked on projects ranging from aircraft hangars, hospitals, gamma knife facilities, clean rooms, large data centers, sports training facilities, and more. He is a demonstrated leader in the fire protection field.