Specific Fire Load
Calculate the specific fire load of a space, q = (mass × LHV) ÷ area, dividing the total energy of the combustible materials (mass × lower heating value) by the floor area. The result, in MJ/m², is the heat that would be released per unit area if all the material burned — the parameter that classifies a building's fire risk and sets protection requirements (fire resistance, exits, sprinklers) in fire codes. The higher the fire load, the more severe the potential fire. Enter the fuel mass, the heating value and the area.
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Specific fire load
The fire load is the fundamental measure of the fuel available in a compartment — how much heat would be released if everything that can burn (furniture, paper, linings, stored goods) actually burned. The specific version normalises that by the floor area: q = (mass × NCV) ÷ area, adding up the energy of each material (its mass times the net calorific value, in MJ/kg) and dividing by the area, which yields MJ/m². This figure underpins the risk classification used in fire codes and in the technical instructions issued by fire departments: rooms with a low fire load (offices, ~300–700 MJ/m²) demand far less than high-load warehouses (record archives, stores of plastics or paper, which run past 2,000 MJ/m²). Concrete requirements follow from the fire load: the required fire resistance rating of the structure (TRRF in Brazilian practice), the need for automatic sprinklers, the number and width of exits, and compartmentation. Day to day, engineers work with the characteristic specific fire load tabulated by occupancy type (already in MJ/m²), but the direct calculation from the materials is what those tabulated values rest on. The higher the load, the more severe and longer-lasting the potential fire — and the more robust the protection has to be. Enter the fuel mass, the calorific value and the area.
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Boiler Efficiency
Calculate the thermal efficiency of a boiler by the direct method, η = (m_steam × Δh) ÷ (m_fuel × LHV) × 100%, comparing the useful heat absorbed by the water/steam (steam flow × enthalpy gain) with the energy released by burning the fuel (fuel flow × lower heating value). The result, in %, shows how much fuel energy actually reached the steam; the rest is lost in flue gases, blowdown, radiation and unburnt fuel. Well-run industrial boilers reach 80–90%. Enter the steam flow, enthalpy gain, fuel flow and LHV.
Pile Allowable Load
Calculate a pile's allowable (working) load, Q_adm = Q_ult ÷ FS, from the ultimate bearing capacity Q_ult (kN) and the global safety factor FS. The allowable load is the maximum load that can be applied to the pile in service with adequate safety — obtained by dividing the ultimate capacity (the load that would cause FAILURE of the pile-soil system) by a safety factor covering uncertainties. The pile-foundation safety factor is typically HIGH (FS = 2.0-2.5 for ultimate capacity, higher if based only on theoretical formulas without a load test), reflecting the great uncertainty in determining soil capacity (unseen, heterogeneous and poorly known) and the severity of a foundation failure (which can collapse the whole structure). Codes often require different partial factors for tip and friction (which have different uncertainties), or limit-state methods. The allowable load sets how many piles are needed for the column loads: number of piles = column load ÷ allowable load. Load tests (measuring real field capacity) allow reducing the safety factor and optimizing design. Enter the ultimate capacity and the safety factor.
Smoke Plume Mass Flow
Calculate the mass flow of a fire's smoke plume by the Heskestad correlation, ṁ = 0.071·Q̇_c^(1/3)·z^(5/3), from the convective part of the heat release rate Q̇_c (kW) and the height above the fire base z (m). The result, in kg/s, is the amount of hot gases and smoke rising and accumulating, governing the design of smoke control and exhaust systems (mechanical or natural) that keep a smoke-free layer for safe evacuation. The flow grows strongly with height. Enter the convective heat fraction and the height.
Required Fire Flow
Calculate the water flow required for a firefighting system, Q = area × application rate, multiplying the operating area (m²) by the required application density (L/min per m²). The result, in L/min, is the minimum flow the sprinkler or spray system must deliver over the most unfavourable area to control the fire. The application rate depends on the occupancy's hazard class — the higher the fire load and combustibility, the higher the density required by codes (NBR/NFPA). It is the basis of hydraulic design and water reserve. Enter the area and the application rate.
Adiabatic Flame Temperature
Estimate the adiabatic flame temperature, T_ad = T_initial + LHV ÷ (m × cp), from the lower heating value LHV (kJ/kg fuel), the mass of combustion products per kg fuel m, the average specific heat of the gases cp (kJ/kg·K) and the initial temperature. The result, in °C, is the maximum theoretical temperature the gases would reach if all the combustion energy heated the products, with no heat loss. It is an upper bound: real flames are cooler (radiation losses, dissociation, excess air). It sets the thermal severity on materials and NOx formation. Enter the LHV, the gas mass, the cp and the initial temperature.
Linear Explosive Charge
Calculate the linear loading density of a blast hole, q = (π/4) × d² × ρ, from the hole diameter d (mm) and the explosive density ρ (g/cm³). The result, in kg of explosive per meter of hole, is how much explosive fits in each meter of charged column — a central parameter of rock blast design. Multiplied by the hole charge height, it gives the charge per hole; combined with the blasted rock volume, it gives the powder factor. Larger diameters and denser explosives raise the linear charge. Enter the hole diameter and the explosive density.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.