Helonic is an AI construction drawing analysis platform for teams researching fire protection symbols during drawing review. Reference for sprinkler heads, fire alarm devices, standpipes, and fire protection equipment
Fire protection is a life safety system. All work must comply with NFPA standards (13, 14, 25, 72) and be approved by the AHJ. For NFPA 13 sprinkler requirements, see our dedicated guide. Never modify fire protection systems without proper authority.
Sprinkler head symbols mark upright, pendent, sidewall, concealed, ESFR, and quick-response heads so reviewers can check orientation and coverage.
| Symbol | Meaning | Notes |
|---|---|---|
| ◉ | Upright Sprinkler | Deflector above pipe, sprays downward |
| ◎ | Pendent Sprinkler | Hangs below pipe, most common type |
| ◐ | Sidewall Sprinkler | Mounts on wall, half-circle spray |
| ◑ | Concealed Sprinkler | Flush with ceiling, drops when activated |
| ⊛ | ESFR Sprinkler | Early Suppression Fast Response |
| ⊚ | Quick Response Sprinkler | QR - faster activation |
Fire protection drawings mark smoke detectors, heat detectors, pull stations, and horn/strobes so reviewers can check device type against the legend.
| Symbol | Meaning | Notes |
|---|---|---|
| ◻S | Smoke Detector | Photoelectric or ionization |
| ◻H | Heat Detector | Fixed temp or rate-of-rise |
| ◻DS | Duct Smoke Detector | In HVAC ductwork |
| □ | Pull Station | Manual fire alarm pull |
| ⬡ | Horn/Strobe | Audible/visual notification |
| ○ | Strobe Only | Visual notification |
| ◇ | Horn Only | Audible notification |
| ▣ | Fire Alarm Control Panel | FACP - main panel |
Standpipe drawings mark hydrants, FDCs, hose cabinets, and fire pumps so reviewers can confirm fire-department access and water supply.
| Symbol | Meaning | Notes |
|---|---|---|
| ⊗FH | Fire Hydrant | Exterior water supply |
| ◯FDC | Fire Dept Connection | Siamese connection for FD |
| ⊕ | Standpipe Riser | Vertical pipe for hose connections |
| ◻ | Fire Hose Cabinet | Contains hose and valve |
| ○ | Hose Valve | 2½" or 1½" connection |
| □ | Fire Extinguisher | Portable extinguisher location |
| ▣ | Fire Pump | Boosts system pressure |
Fire protection drawings mark OS&Y valves, PIVs, check valves, and tamper switches so reviewers can confirm isolation and supervision.
| Symbol | Meaning | Notes |
|---|---|---|
| ⊗OS&Y | OS&Y Valve | Outside Screw & Yoke gate valve |
| ⊗PIV | Post Indicator Valve | Shows open/shut position |
| ◇ | Check Valve | Prevents backflow |
| △ | Pressure Switch | Monitors system pressure |
| ▽ | Flow Switch | Detects water flow |
| ⊙ | Pressure Gauge | Visual pressure reading |
| ⬡ | Tamper Switch | Monitors valve position |
Riser and pipe symbols mark fire-protection mains, sprinkler branches, and dry or deluge valves so reviewers can trace water from the supply to the heads.
| Symbol | Meaning | Notes |
|---|---|---|
| , , FP, , | Fire Protection Main | Primary supply pipe |
| , , SB, , | Sprinkler Branch | Branch line to heads |
| - - FP - - | Underground Fire Line | Below grade piping |
| , ▷, | Alarm Check Valve | Activates alarm on flow |
| , ||, | Dry Pipe Valve | For dry pipe systems |
| , ◇, | Deluge Valve | For deluge systems |
Wet-pipe systems keep pipes filled with water, while dry, preaction, and deluge systems stay empty until a detection event opens the valve.
Pipes filled with water. Fastest response. Most common system type.
Pipes filled with pressurized air. For areas subject to freezing.
Dry pipes that require alarm activation before water enters. For sensitive areas.
All heads open (no fusible link). All heads discharge simultaneously.
Related references for fire protection drawing review.
F-rating, T-rating, and installation
Line types for fire walls and barriers
Detailed reference for alarm device symbols and circuits
Best practices for reviewing FP plan sets
AI-powered fire protection coordination checks
Step-by-step guide to sprinkler plan sheets