A practical FDC guide for project engineers, MRO teams, and procurement managers
Fire department connections (FDCs) are small components with outsized impact: they’re the interface that lets responding crews supplement a sprinkler or standpipe system quickly. When FDC specifications miss the mark—wrong thread, unclear signage, poor access, or mismatched caps—minutes can be lost at the curb. This guide breaks down how to specify FDCs that align with common U.S. requirements, coordinate with local authority having jurisdiction (AHJ), and support smoother purchasing for both domestic projects and export-ready packages.
What an FDC actually does (and what it doesn’t)
An FDC is a dedicated inlet that allows the fire department to pump water into a building’s fire protection piping—most commonly a standpipe system, a sprinkler system, or a combined standpipe/sprinkler arrangement. The FDC doesn’t replace your primary water supply; it’s a redundancy and an operational tool for incident response. Because it’s a “handoff point” between the public response side (fire department hose lines) and the private system side (building piping), standardization and clarity matter: crews must identify the connection, connect quickly, and pump to the correct pressure.
Key specification points that prevent common FDC failures
1) Location & access (design for the fireground, not the drawing set)
NFPA 14 requires FDCs to be arranged so hose lines can be attached without interference (vehicles, landscaping, fences, posts, and even other FDCs). It also places the FDC within a typical maximum distance of 100 ft of the nearest hydrant (unless AHJ approves otherwise) and sets a common mounting height range of 18–48 inches above grade. (firesolution.id)
NFPA 14 requires FDCs to be arranged so hose lines can be attached without interference (vehicles, landscaping, fences, posts, and even other FDCs). It also places the FDC within a typical maximum distance of 100 ft of the nearest hydrant (unless AHJ approves otherwise) and sets a common mounting height range of 18–48 inches above grade. (firesolution.id)
2) Signage that communicates service and required pressure
NFPA 14 calls for an identifying sign (commonly “STANDPIPE”) and requires that signage indicate details such as manual vs. automatic and the pressure required at the inlets to meet system demand. For combined services, signage must identify both (e.g., standpipe and sprinkler). (firesolution.id)
NFPA 14 calls for an identifying sign (commonly “STANDPIPE”) and requires that signage indicate details such as manual vs. automatic and the pressure required at the inlets to meet system demand. For combined services, signage must identify both (e.g., standpipe and sprinkler). (firesolution.id)
3) Inlet count that matches hydraulics (and AHJ expectations)
Many jurisdictions expect at least two 2½-inch inlets as a baseline configuration for standpipe FDCs, with additional inlets where demand warrants. Where you land on inlet quantity should be coordinated with the fire protection engineer and local fire department/AHJ to avoid last-minute rework. (fps-eg.com)
Many jurisdictions expect at least two 2½-inch inlets as a baseline configuration for standpipe FDCs, with additional inlets where demand warrants. Where you land on inlet quantity should be coordinated with the fire protection engineer and local fire department/AHJ to avoid last-minute rework. (fps-eg.com)
4) Thread type: “standard” is local
A frequent procurement pitfall is ordering an FDC with the wrong thread. While NH/NST-style threads are widespread, thread incompatibilities exist across the U.S. and internationally. NFPA 14 also allows the AHJ to designate alternate threads where local fire department threads do not conform. Treat thread selection as a coordination item, not a default. (studocu.com)
A frequent procurement pitfall is ordering an FDC with the wrong thread. While NH/NST-style threads are widespread, thread incompatibilities exist across the U.S. and internationally. NFPA 14 also allows the AHJ to designate alternate threads where local fire department threads do not conform. Treat thread selection as a coordination item, not a default. (studocu.com)
5) Caps, plugs, and security that don’t slow crews down
NFPA 14 requires FDCs to be equipped with approved plugs or caps that are properly secured yet easy to remove. In real-world terms: corrosion resistance, tethering/chain choices, and cap style can help prevent damage, vandalism, and delays at connection time. (firesolution.id)
NFPA 14 requires FDCs to be equipped with approved plugs or caps that are properly secured yet easy to remove. In real-world terms: corrosion resistance, tethering/chain choices, and cap style can help prevent damage, vandalism, and delays at connection time. (firesolution.id)
Spec checklist: what to confirm before you buy (or export)
For procurement and project teams, a short pre-purchase checklist prevents mismatches that show up during final inspection:
Confirm with the engineer and AHJ:
• System served: standpipe, sprinkler, combined, fire pump feed, or special hazard
• Required inlet pressure to achieve design demand (for signage)
• Inlet size/count and orientation (straight, 45°, clappered Siamese, Storz where permitted)
• Thread type (NH/NST vs local designated vs Storz) and cap compatibility
• Placement constraints: clearance, vehicle impact protection, freeze protection considerations
• Material/coating requirements (corrosion exposure, coastal, industrial atmosphere)
Quick comparison table: FDC options that affect field usability
| Decision point | Common choices | Why it matters at inspection & incident |
|---|---|---|
| Inlet interface | 2½” NH/NST swivels; Storz (where allowed); AHJ-designated local thread | Prevents cross-threading, adapter scramble, and delays; supports mutual aid compatibility. (en.wikipedia.org) |
| Signage content | Service label + manual/auto + required inlet pressure | Helps crews pump correctly and avoids under/over-pressurizing standpipe operations. (firesolution.id) |
| Caps & security | Tethered caps; breakaway chains; tamper-resistant options | Reduces debris ingress and vandalism while remaining “easy removal” for the fire department. (firesolution.id) |
| Placement | Street-visible; protected from vehicles; within common distance limits | Avoids “can’t connect” scenarios caused by parked vehicles, fencing, or poor clearance. (firesolution.id) |
Did you know? Fast facts that influence FDC decisions
FDC signage is not just “nice to have.” NFPA 14 requires identification and pressure information so crews can make faster, safer pump decisions. (firesolution.id)
Distance and mounting height are commonly prescriptive. Typical criteria include a maximum distance from a hydrant and a mounting range of 18–48 inches above grade. (firesolution.id)
Thread incompatibility is real—even inside the U.S. Mutual aid events and multi-jurisdiction projects are where “default thread assumptions” become expensive. (en.wikipedia.org)
U.S. coordination angle: why “local standard” still matters nationwide
IFW Supply supports buyers across key U.S. metros (Boise, Salt Lake City, Denver, Phoenix, Seattle) as well as export-driven procurement. Even within the United States, FDC decisions can vary by fire department and AHJ—especially around thread compatibility, preferred inlet style, and signage conventions. NFPA 14 explicitly recognizes AHJ authority to designate connections where local threads differ, which is why early coordination (and documenting the decision on submittals and purchase orders) reduces field conflict. (studocu.com)
Sourcing support: simplify FDC procurement from submittal to shipment
For procurement teams, the “right” FDC is the one that arrives ready to install and passes inspection without change orders. That usually means bundling the connection body, inlets, caps/plugs, signage, and any necessary adapters as a coordinated package, aligned to the engineer’s demand and the AHJ’s connection standard. If you’re buying for multiple facilities or shipping internationally, it also helps to confirm labeling language, packaging, and documentation requirements early.
Need help specifying a fire department connection package?
Share your system type, required demand/pressure (if available), and the AHJ/fire department thread requirement. IFW Supply can help you line up compatible inlets, caps, signage, and ship-ready documentation—whether you’re buying for a U.S. jobsite or consolidating an export order.
Tip for faster turnaround: include location (city/state), system served (standpipe/sprinkler/combined), inlet thread type, and preferred finish/material.
FAQ: Fire Department Connections (FDCs)
How high should an FDC be mounted?
NFPA 14 commonly sets FDC mounting height between 18 inches and 48 inches above adjacent grade/sidewalk/ground surface. Always confirm local amendments and accessibility constraints. (firesolution.id)
NFPA 14 commonly sets FDC mounting height between 18 inches and 48 inches above adjacent grade/sidewalk/ground surface. Always confirm local amendments and accessibility constraints. (firesolution.id)
How close does the FDC need to be to a hydrant?
NFPA 14 includes a typical maximum of 100 feet from the nearest hydrant connected to an approved water supply, unless the AHJ approves a longer distance. (firesolution.id)
NFPA 14 includes a typical maximum of 100 feet from the nearest hydrant connected to an approved water supply, unless the AHJ approves a longer distance. (firesolution.id)
Do I need signage that shows required inlet pressure?
Yes—NFPA 14 requires the sign to indicate the pressure required at the inlets to deliver the system demand, in addition to identifying the served system(s). (firesolution.id)
Yes—NFPA 14 requires the sign to indicate the pressure required at the inlets to deliver the system demand, in addition to identifying the served system(s). (firesolution.id)
Is NH/NST thread always acceptable for FDC inlets?
It’s common, but not universal. NFPA 14 allows the AHJ to designate alternate connections where local fire department threads do not conform. Confirm thread requirements early—especially on multi-city programs and retrofit work. (studocu.com)
It’s common, but not universal. NFPA 14 allows the AHJ to designate alternate connections where local fire department threads do not conform. Confirm thread requirements early—especially on multi-city programs and retrofit work. (studocu.com)
What’s the most common reason FDCs fail in the field?
Avoidable coordination gaps: wrong thread/caps, poor access due to site features, and signage that doesn’t identify service type or required pressure. These aren’t “product quality” issues as much as “spec completeness” issues—solved by aligning engineer, AHJ, and procurement before the order is cut. (firesolution.id)
Avoidable coordination gaps: wrong thread/caps, poor access due to site features, and signage that doesn’t identify service type or required pressure. These aren’t “product quality” issues as much as “spec completeness” issues—solved by aligning engineer, AHJ, and procurement before the order is cut. (firesolution.id)
Glossary (plain-English)
AHJ (Authority Having Jurisdiction): The code-enforcing body (often the fire marshal or building department) that approves equipment choices, locations, and connection standards.
FDC (Fire Department Connection): The inlet connection that allows the fire department to pump water into a sprinkler/standpipe system. (firesolution.id)
NH / NST: Common fire service hose thread naming used across many U.S. jurisdictions; compatibility is widespread but not guaranteed everywhere. (en.wikipedia.org)
Standpipe system: A system of piping and valves in a building intended to provide water for firefighting hose lines, typically in stairwells or hose cabinets (requirements and types are covered under NFPA 14). (firesolution.id)
System demand (flow/pressure): The hydraulic requirement the system must deliver; NFPA 14 requires FDC signage to indicate required inlet pressure to achieve that demand. (firesolution.id)