Volumetric Organic Loading Rate
Calculate the volumetric organic loading rate (OLR) of a biological reactor, OLR = BOD load ÷ volume, dividing the influent organic load (kg BOD/day) by the reactor's working volume (m³). The result, in kg BOD/(m³·day), shows how much organic matter is applied per unit volume and is central to sizing lagoons, trickling filters, UASB and activated sludge: high loads demand more biomass and oxygen, while low loads indicate an oversized reactor. Enter the daily BOD load and the reactor volume.
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Volumetric organic loading rate (VOLR)
The volumetric organic loading rate (VOLR) answers a design question: how much organic matter am I feeding into each cubic metre of reactor every day? It is VOLR = BOD load ÷ volume, with the load given in kg of BOD (biochemical oxygen demand — the measure of biodegradable organic matter) per day and the working volume of the reactor in m³, which yields kg BOD/(m³·day). It is one of the most widely used parameters for sizing stabilisation ponds, trickling filters, UASB reactors and activated sludge tanks. Every reactor type has an optimum VOLR range: loading it above that range overwhelms the biomass, drives treatment efficiency down and can cause foul odours; loading it far below the range means an oversized and needlessly expensive reactor. Together with the surface organic loading rate and the hydraulic retention time, the VOLR turns the real sewage flow and strength into an appropriate reactor volume. Enter the daily BOD load and the reactor volume.
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Warm-Up Condensate Load (Steam)
Computes the average condensate flow generated while a steam line or piece of equipment is warming up, m = M × c_p × (T_final − T_initial) ÷ (h_fg × t), that is, the sensible heat absorbed by the cold metal divided by the latent heat of the steam and by the time in which the warm-up is to be completed. This average warm-up flow, weighed against the running load, is what sizes the steam trap — take the larger of the two, with a factor of 2 to 3 on the warm-up figure, since the peak in the first minutes runs well above the average: on start-up cold pipework condenses far more steam than it does once hot, and a trap picked from the running load alone floods the line and invites water hammer. Carbon steel has a specific heat around 0.49 kJ/kg·K, and latent heat drops as pressure rises — at 170 °C (about 7 bar gauge) it is roughly 2049 kJ/kg. Enter the metal mass, the specific heat, the initial and final temperatures, the latent heat of the steam and the warm-up time.
Railcar Axle Load
Calculate a rail vehicle's axle load, P_axle = total weight ÷ number of axles, from the gross weight of the wagon or locomotive (N, tare plus load) and the number of axles. Axle load is the most important parameter for track design: it is the force each axle transmits to the track (and, per wheel, to each rail), governing stresses in the rail, sleepers, ballast and subgrade. Railways are classified by their axle-load capacity: heavy-haul railways (such as ore lines) run at 30-40 tonnes per axle and need heavy rail, concrete sleepers and reinforced ballast; passenger and light-freight lines run lower loads. Exceeding the allowable axle load causes accelerated fatigue, permanent deformation and failures — so rolling-stock and track-class compatibility is strictly controlled. Axle load also limits maximum train weight and thus transport productivity. Enter the total weight and the number of axles.
Axle Load Equivalency Factor
Computes how many passes of the standard axle are equivalent to one pass of the real axle, using the power law of pavement design: factor = (axle load ÷ standard axle load) raised to the damage exponent. This factor is what converts a traffic count into the number N of standard axle repetitions, which in Brazil is the 8.2 tf, or 80 kN, single axle with dual wheels. The exponent amplifies overload brutally: an axle 20% heavier than the standard does not consume 20% more pavement but 2.07 times as much, which is why a single overloaded truck weighs more on the life of the road than thousands of cars, whose factor is practically zero. The exponent is an input rather than fixed at 4, the AASHTO value known as the fourth power law, because rigid pavement and fatigue cracking models work with exponents between 3 and 5 and the result shifts by a whole level depending on the choice. Enter the axle load, the standard axle load and the damage exponent.
Hydraulic Retention Time (HRT)
Calculate the hydraulic retention time (HRT) of a reactor or tank, HRT = volume ÷ flow, dividing the working volume (m³) by the influent flow (m³/h). The result, in hours, is the average time the liquid stays in the unit and is decisive in designing clarifiers, anaerobic reactors, lagoons and aeration tanks: short times prevent reactions or settling from completing, while long times raise cost and footprint. Enter the working volume and the inlet flow.
Carbon/Nitrogen Ratio (C/N)
Compute the C/N ratio of an organic material by dividing the carbon content by the nitrogen content. It governs composting and decomposition: the ideal range to compost is ~25–30/1. A high ratio (straw, sawdust) breaks down slowly and immobilizes nitrogen; a low one (manure, legumes) breaks down fast and releases ammonia. Balancing 'brown' and 'green' materials starts here. Enter the carbon and nitrogen contents.
Velocity Gradient (Mixing)
Calculate the mean velocity gradient (G) in rapid-mix and flocculation chambers, G = √(P ÷ (μ × V)), from the dissipated power (W), the water dynamic viscosity (Pa·s) and the chamber volume (m³). The result, in s⁻¹, measures mixing intensity: rapid mixing needs high G (700–1000 s⁻¹) to disperse the coagulant, while flocculation uses low G (20–70 s⁻¹) to promote floc collision and growth without breaking them. Enter power, viscosity and volume.
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.