Fire-Ground Engineering

Tools in this group

• Fire Hose Friction Loss - CQ^2L formula by hose diameter, length, GPM.
• Pump Discharge Pressure - Required PDP from nozzle, friction, elevation.
• Hydrant Flow - GPM from Pitot pressure and outlet diameter.
• Required Fire Flow - ISO method from square footage and exposure.
• Master Stream Reach - Reach from nozzle pressure and type.
• Aerial Ladder Reach - Horizontal and vertical reach from angle and extension.
• Foam Concentrate - Required foam volume by class and application rate.
• Smoke Reading Reference - Volume, velocity, density, and color interpretation.
• Reverse-Lay Friction Loss - Single-pump and tandem (parallel) supply friction loss.
• Sprinkler GPM Density - Total gpm from area of operation and density (gpm/ft^2).
• Standpipe Friction Loss - Riser elevation plus per-outlet friction.
• Ladder Pipe Reach - Aerial geometry combined with master-stream forward reach.
• Vehicle Braking Distance - Stopping distance from speed, friction, grade, reaction time.
• Confined Space Air Change Time - Minutes to reach target air changes from blower CFM.
• Rope Rescue Mechanical Advantage - Theoretical and actual MA across rig types with pulley losses.
• Sling Angle Load Multiplier - Tension per leg from load, configuration, and included angle.
• ISO Needed Fire Flow - NFF = Ci × Oi × (1 + X + P) per the ISO Public Protection Classification; Ci = 18 × F × sqrt(A) by construction class. Rounded to 250 gpm; capped at 12 000 gpm.
• SCBA Cylinder Work Time - Time to low-air alarm and to empty from rated scf, current pressure, alarm pressure, and consumption rate. NFPA 1981 governs cylinder ratings; exit at the alarm, not at empty.
• NFPA 1142 Rural Water Supply - Minimum on-site water supply Q = (V * occupancy * construction) / 5 per NFPA 1142 §5, with 1.5x exposure and 0.5x sprinkler multipliers; recommended tanker trip count.
• Confined-Space Pre-Entry Ventilation (OSHA 1910.146) - L x W x H volume, contaminant-driven target ACH (combustible / O2-deficient / H2S / CO / general), minutes-to-purge and steady-state ACH, plus the 1910.146(d)(5) 4-gas-meter reminder. Companion to the v3 confined-space-purge tile.
• Standpipe Pump Discharge Pressure (NFPA 14) - Required pump discharge pressure = nozzle pressure + supply-hose friction (NFA CQ^2L) + appliance loss + elevation (0.434 psi/ft), with a high-rise flag. SOP and incident command govern.
• Smoke Ejector / Ventilation CFM (NFPA 1500) - Required CFM for a target air-change rate, fans needed, time to one air change, and the exhaust-to-entry opening ratio for negative-pressure ventilation. SOP and incident command govern.
• Nozzle / Fire-Stream Reaction Force - Nozzle reaction force for a smooth-bore (1.57 d^2 NP) or fog (0.0505 Q sqrt(NP)) stream, with a staffing note vs. the ~60 / ~75 lb thresholds. Per IFSTA Pumping Apparatus Driver/Operator.
• Sprinkler K-Factor Solver - Solve Q = K x sqrt(P) for flow, pressure, or K-factor. Per NFPA 13; complements the sprinkler-density tile.
• Elevation Pressure Loss / Gain - Standpipe elevation pressure loss or gain shown both as the exact hydrostatic value (0.434 psi/ft) and the fire-ground 5-psi-per-floor rule of thumb, by floors or feet.
• Water-Supply Duration - Sustainable duration of an available water volume at a selected flow, with the net drawdown time and steady-state sustainable flow when a continuous resupply rate is entered.
• National Fire Academy Quick Fire-Flow - The fireground size-up quick-calc: NFF = (L x W / 3) x (percent involved / 100) x floors, plus 25% of the base per exposure. Validated only for interior/offensive attack up to ~50% involvement and ~1,000 gpm -- beyond that it under-predicts and the fight is defensive (use the ISO / required-fire-flow method). A mental scene-size-up tool, not a water-supply design.
• Iowa Rate-of-Flow (Volume Method) - The Royer-Nelson volume-method fire flow, beside the area-based NFA formula: volume = L x W x H, total water = volume / 200 (one gallon controls ~200 ft^3), rate = volume / 100 (that water in the 30-second knockdown burst). A 20 x 30 x 10 ft room is 6,000 ft^3 -> 30 gal, 60 gpm - a fraction of the NFA's 200 gpm for the same footprint, because Iowa is a brief interior knockdown burst and the NFA is sustained. A fire-behavior teaching and size-up aid, not a water-supply design.
• Relay Pumping Max Distance - Maximum distance between pumpers in a relay: budget = max discharge - intake residual - 0.434 x elevation; FL_per_100 = C x (Q/100)^2; distance = budget / FL_per_100 x 100. The next intake needs 20 psi or it cavitates, and the distance falls with the square of flow. A planning aid, not incident command.
• Drafting Maximum Lift (Altitude-Corrected) - Maximum drafting lift from a static source: theoretical = 33.9 - elevation/1000; attainable = factor x theoretical - suction losses (factor about 2/3). A real pump cannot pull a perfect vacuum, and every 1,000 ft of altitude shaves a foot -- lift is set by atmosphere pushing water up the suction, not the pump. A planning aid, not incident command.
• Vacuum Gauge to Drafting Lift Readout - Reads the compound (vacuum) gauge during a draft: suction_head = vacuum_inHg x 1.13, against the altitude-corrected attainable ceiling (factor x (33.9 - elevation/1000)) with the margin left. 10 in Hg at sea level is 11.3 ft, only half the ~22.6 ft ceiling; 18 in Hg at 3,000 ft is 98% of the ceiling - the pump about to lose prime. Turns the gauge needle into feet and a cavitation warning. Pairs with draft-lift-max (the ceiling). A readout aid, not incident command.
• Tanker (Water Shuttle) Flow Capability - Sustained rural shuttle flow: usable = nominal x fraction (ISO ~0.90); shuttle_flow = usable x tankers / cycle (fill + dump + round-trip). The fleet flow is capped by the slowest link -- usually the fill or dump site, not the tank size -- so a fourth tanker adds nothing if the fill pump cannot turn it around. A planning aid, not incident command.
• Tanker Shuttle Cycle Time - Builds the cycle time tanker-shuttle-flow needs from the four field measurements: fill = tank/fill_gpm, dump = tank/dump_gpm, travel = 2 x distance/speed (round trip), cycle = fill + dump + travel, and one tanker sustains tank/cycle. A 3,000-gal tanker filling and dumping at 1,000 gpm over a 2-mile haul at 35 mph runs a 12.9-min cycle and sustains only 233 gpm alone - which is why rural supply needs a fleet. Techs forget the dump time or count one-way travel; both oversize the flow. A planning aid, not incident command.
• Tanker Shuttle Fill-Site-Limited Fleet Size - How many tankers is enough: past some fleet the water supply stops climbing because the bottleneck is the slowest fixed site, not the truck count. bottleneck = max(tank/fill_gpm, tank/dump_gpm); fleet = ceil(cycle / bottleneck); ceiling flow = tank / bottleneck. A 3,000-gal operation at 1,000 gpm fill and dump over a 2-mile haul needs 5 tankers to reach its 1,000-gpm ceiling; a sixth just queues. Slow the fill to 500 gpm and 3 tankers cap it at 500 gpm - the fix is a faster site, not more trucks. A planning aid, not incident command.
• Foam Eductor Back-Pressure / Hose-Lay Limit - In-line eductor limit: max_back_pressure = 0.65 x inlet; max hose length = (0.65 x inlet - nozzle - 0.434 x elevation) / (C x (Q/100)^2) x 100. If the back-pressure exceeds ~65% of inlet the eductor stops drawing foam concentrate entirely (not less, none) while water keeps flowing. A planning aid, not incident command.
• Spot Smoke / Heat Detector Count (Smooth Ceiling) - Spot smoke or heat detectors on a smooth ceiling per NFPA 72: rows = ceil(length / listed spacing); columns = ceil(width / spacing); detectors = rows x columns; the first detector sits within spacing/2 of each wall. A 60 x 40 ft room at a 30 ft listed spacing takes 4 detectors (a 2 x 2 grid, 15 ft off each wall); a 100 x 80 ft open area takes 12. The 0.7-times-spacing rule confirms every point is covered; beams, high ceilings, and HVAC tighten it. Like sprinkler-head-layout, an install estimate the stamped fire-alarm plan and AHJ govern.
• Dry-Pipe / Preaction Air Compressor CFM - The compressor free-air CFM to restore a dry-pipe or preaction system's normal air pressure within the NFPA 13 time limit (30 minutes standard): free air = (system gal / 7.48) x (normal psig / 14.7) / restore minutes. A 400-gal dry system to 40 psi in 30 min needs about 4.85 CFM; a 750-gal system 9.1 CFM -- spec the next larger unit. A listed automatic air-maintenance device (not a shop compressor) is required, and a corrosion-mitigating air or nitrogen source is preferred. The system volume comes from the pipe schedule, the pressure is set to hold the clapper closed with margin, and NFPA 13 / the AHJ set the restore time. A sizing estimate; the compressor's rating at the pressure and the AHJ govern.
• Jockey (Pressure-Maintenance) Pump Sizing (NFPA 20) - The jockey pump flow and the staggered pressure-switch settings for a fire-pump system, per NFPA 20 practice: jockey flow is small (about 1% of the fire pump's rated flow, at least 1 gpm) so it makes up leakage without the fire pump starting on every drop -- a 750 gpm fire pump takes about a 7.5 gpm jockey. The switches stagger so the jockey acts first: jockey stop = fire-pump churn (shutoff) pressure + minimum static supply (170 psi for a 120 psi churn and 50 psi static); jockey start = stop - 10 (160); fire-pump start = jockey start - 5 (155). A too-large jockey masks a real flow and fails to start the fire pump on a fire. A settings guide; NFPA 20, the pressure switches, and the AHJ / stamped fire-pump design govern.
• Hydrant Rated Flow at 20 psi (NFPA 291) - Hydrant rated capacity at 20 psi residual: QR = QF (hr/hf)^0.54, hf = static - residual, hr = static - 20, with the AA/A/B/C color class. Static 70, residual 50, QF 1000 gpm -> 1640 gpm, Class AA; static 65, residual 45, QF 800 -> 1240 gpm, Class A. A field/planning estimate; the water authority's data govern.
• Required Fall-Arrest Clearance (ANSI Z359) - The clearance a personal fall-arrest system needs below the anchor so the worker does not strike the level: RFC = free-fall distance + deceleration distance + worker height (D-ring to feet) + safety margin. A 6 ft free fall, 3.5 ft deceleration (the Z359 lanyard cap), 5 ft worker, and 3 ft margin needs 17.5 ft. Enter each explicitly - free-fall depends on the anchor position; an SRL cuts both the free-fall and deceleration. Per ANSI Z359.1 / OSHA 1926 Subpart M; the equipment instructions and a competent person govern.
• Max Fire Area from Available Foam Concentrate - The inverse of the foam-concentrate tile: the largest fire area the concentrate on the apparatus can cover for the full duration, max area = concentrate / (application rate x foam percentage x duration). 100 gal at 0.10 gpm/ft^2, 3%, 15 min covers up to ~2,222 ft^2; a leaner percentage or shorter duration stretches it further. The rate and duration come from the fuel and the SOP. A planning aid; incident command governs.
• Smooth-Bore Nozzle Flow (GPM) - The flow from a smooth-bore (solid-stream) nozzle: gpm = 29.7 x tip diameter^2 x sqrt(nozzle pressure), with the companion nozzle reaction 1.57 x d^2 x NP. Standard nozzle pressure is 50 psi on a handline and 80 psi on a master stream (both editable). A discharge estimate; incident command and the pump operator govern the actual flow target.
• Smooth-Bore Tip Diameter for a Target Flow - The inverse of the smooth-bore-flow tile: the tip (bore) diameter a target flow needs at a nozzle pressure, d = sqrt( gpm / (29.7 x sqrt(NP)) ). 250 gpm at 50 psi wants a 1.09 in tip (round up to a stocked 1-1/8 in), which handles about 93 lb of reaction. Answers 'what tip for this flow' instead of the flow from a set tip. Round to a stocked size; incident command and the pump operator govern.
• Fire Pump Rated / Churn / Overload Curve Check (NFPA 20) - Whether a stationary fire pump sits inside the NFPA 20 three-point envelope: the churn (no-flow) ceiling at 140% of rated pressure, and the overload floor of 65% of rated pressure at 150% of rated flow, with a pass/fail and the margin at each end of the curve. A 500 gpm at 100 psi pump must hold under 140 psi at churn and over 65 psi at 750 gpm. A flat, high-shutoff curve fails churn and drives a pressure-relief-valve requirement; a weak curve fails the overload reserve the sprinkler demand needs. A design and acceptance-check aid, not a stamped fire-pump submittal; a qualified fire-protection engineer and the AHJ govern.
• Sprinkler System Demand and Water Supply (NFPA 13) - From the discharge density on the floor to the water supply the system is designed around: sprinkler demand = density x design area, plus the inside/outside hose-stream allowance, held for the required duration to give the stored volume. An Ordinary Hazard Group 2 space at 0.20 gpm/ft^2 over 1,500 ft^2 plus 250 gpm of hose for 90 minutes needs 550 gpm and 49,500 gallons, the numbers that size the fire pump and the tank. The area/density screening demand; the full most-remote-area hydraulic calculation is a separate analysis. A design aid, not a stamped hydraulic submittal; a qualified fire-protection engineer and the AHJ govern.
• Max Sprinkler Design Area for a Water Supply (NFPA 13) - The inverse of the sprinkler-demand tile: the largest hydraulic design area a water supply can serve at a density, once the hose allowance is taken off the top, max area = (supply - hose) / density. A 550-gpm supply with 250 gpm of hose at 0.20 gpm/ft^2 covers up to 1,500 ft^2; a lighter hazard (lower density) covers more. The area/density screen; a most-remote-area hydraulic calculation governs. A design aid; a fire-protection engineer and the AHJ govern.
• Sprinkler Head Count and Spacing (NFPA 13) - How many sprinkler heads a room needs, how far apart, and how far off the walls: the governing spacing is the smaller of the linear cap and sqrt(protection area per head), then heads per line, lines, the total head count, the achieved area per head, and the maximum wall distance (spacing / 2). For ordinary hazard the 130 ft^2 area cap forces a spacing near 11.4 ft, tighter than the 15 ft linear cap, so a 40 x 30 ft room takes 12 heads rather than a naive 15-ft-grid's 6. A rectangular-bay standard-spray estimate; obstructions, the beam rule, and minimum head spacing are separate checks. A takeoff aid, not a stamped sprinkler layout; a qualified fire-protection designer and the AHJ govern.
• Sprinkler Pressure Demand at the Base of Riser (NFPA 13) - The pressure the water supply must deliver at the base of the riser to drive the hydraulically most remote sprinkler: the K-factor start pressure at the end head (P1 = (Q/K)^2), plus the NFPA 13 Hazen-Williams friction loss p = 4.52 Q^1.85 / (C^1.85 d^4.87) carried over the governing run, plus the 0.433 psi/ft elevation head to lift the water. A 26 gpm K-5.6 head needs 21.6 psi, and 260 gpm through 150 ft of 3 in steel adds 12.1 psi of friction and 6.5 psi of lift for a 40.1 psi demand - the point that must fall under the supply curve and the fire pump's rated point. Smoother CPVC (C = 150) trims about 4 psi. One representative flowing path; a full design balances every node and grid loop. A design aid, not a stamped hydraulic submittal; a qualified fire-protection engineer and the AHJ govern.