Rate of Filtration Calculation

Filtration Rate & Flux Calculator

Liters (L) Milliliters (mL) Cubic Meters (m³)

Square Meters (m²) Square Centimeters (cm²) Square Feet (ft²)

Minutes Hours Seconds

Calculation Results

Volumetric Flow Rate 0 Liters/Hour

Filtration Flux (J) 0 LMH (L/m²/h)

---

Understanding the Rate of Filtration

Filtration is a critical physical process used in laboratories, industrial manufacturing, and water treatment to separate solids from fluids. Calculating the rate of filtration is essential for sizing equipment, predicting processing times, and ensuring efficiency in chemical engineering and pharmaceutical production.

The Core Formulas

There are two primary ways to measure filtration efficiency:

1. Volumetric Flow Rate (Q): This measures the volume of fluid passing through the filter per unit of time.
   Formula: Q = V / t
2. Filtration Flux (J): This is the flow rate per unit of filter area. Flux is the standard metric for comparing the efficiency of different membrane systems.
   Formula: J = V / (A × t)

Factors Affecting Filtration Speed

• Pressure Differential: Higher pressure typically increases the filtration rate, though it may compress the filter cake, eventually slowing the process.
• Viscosity: Thick, viscous liquids filter much more slowly than thin liquids like water.
• Filter Media Resistance: The pore size and thickness of the filter material determine how much resistance the fluid encounters.
• Cake Build-up: As solids accumulate on the filter, they create an additional layer (the "cake") that usually slows down the rate of filtration over time.

Practical Example

Imagine a pharmaceutical lab filtering 1,000 Liters of a solution through a membrane with a surface area of 5 Square Meters. If the process takes 2 Hours:

• Volumetric Rate: 1,000 L / 2 h = 500 L/hr.
• Filtration Flux: 500 L/hr / 5 m² = 100 L/m²/h (LMH).

Using these metrics, engineers can determine if the pump is correctly sized or if a larger filter area is required to meet production deadlines.

function calculateFiltration() { var volume = parseFloat(document.getElementById("filtrateVolume").value); var volUnit = parseFloat(document.getElementById("volumeUnit").value); var area = parseFloat(document.getElementById("filterArea").value); var areaUnit = parseFloat(document.getElementById("areaUnit").value); var time = parseFloat(document.getElementById("filtrationTime").value); var timeUnit = parseFloat(document.getElementById("timeUnit").value); if (isNaN(volume) || isNaN(area) || isNaN(time) || volume <= 0 || area <= 0 || time <= 0) { alert("Please enter valid positive numbers for all fields."); return; } // Convert everything to standard units: Liters, Square Meters, Hours var volumeInLiters = volume * volUnit; var areaInM2 = area * areaUnit; var timeInHours = (time * timeUnit) / 3600; // Calculations var flowRate = volumeInLiters / timeInHours; // L/h var flux = flowRate / areaInM2; // L/m2/h (LMH) // Display Results document.getElementById("volRateDisplay").innerText = flowRate.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById("fluxRateDisplay").innerText = flux.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById("resultsArea").style.display = "block"; // Scroll to results document.getElementById("resultsArea").scrollIntoView({behavior: 'smooth'}); }