Oxygen Transmission Rate Calculation

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Oxygen Transmission Rate (OTR) Calculator

Unit: cc · mm / (m² · day · atm)
Unit: mm (millimeter)
Unit: atm (Atmospheres). Use 0.21 for normal air.

Calculated OTR

cc / (m² · day)

Understanding Oxygen Transmission Rate (OTR)

Oxygen Transmission Rate (OTR) is a critical measurement in packaging science, representing the steady-state rate at which oxygen gas permeates through a plastic film or barrier material. This metric is vital for food manufacturers, pharmaceutical companies, and electronic component producers to ensure product shelf-life and prevent oxidation.

The Mathematical Formula

The standard calculation for OTR is derived from Fick's Law of Diffusion. The relationship between permeability, thickness, and pressure is expressed as:

OTR = (P × Δp) / L
  • OTR: Oxygen Transmission Rate [cc / (m² · day)]
  • P: Permeability Coefficient of the material
  • Δp: Partial pressure difference across the film (usually 1 atm or 0.21 atm for air)
  • L: Thickness of the material (mm)

Why OTR Matters in Packaging

In the food industry, oxygen is often the primary cause of spoilage. High OTR materials are suitable for fresh produce that needs to "breathe," while low OTR (high barrier) materials are required for fatty foods, snacks, and meats to prevent rancidity and discoloration.

Practical Example Calculation

Imagine you are using a Polyethylene (LDPE) film with a thickness of 0.05 mm. The permeability coefficient (P) for this material is approximately 150 cc·mm/(m²·day·atm). If you are packaging the product in normal air conditions (where the partial pressure of oxygen is 0.21 atm):

  1. Permeability (P) = 150
  2. Pressure (Δp) = 0.21
  3. Thickness (L) = 0.05
  4. Calculation: (150 × 0.21) / 0.05 = 630 cc / (m² · day)

This resulting OTR tells you how many cubic centimeters of oxygen will pass through every square meter of your packaging every 24 hours.

Factors Affecting OTR

  • Temperature: Permeability increases exponentially as temperature rises. Most OTR tests are standardized at 23°C.
  • Humidity: For certain materials like EVOH or Nylon, relative humidity (RH) significantly affects the oxygen barrier properties.
  • Coating: Adding metallic or ceramic layers (like Al2O3) can reduce OTR by orders of magnitude.
function calculateOTR() { var p = parseFloat(document.getElementById('permeability').value); var thickness = parseFloat(document.getElementById('thickness').value); var deltaP = parseFloat(document.getElementById('pressureDiff').value); var resultDisplay = document.getElementById('otr-result-box'); var valueDisplay = document.getElementById('otr-value'); if (isNaN(p) || isNaN(thickness) || isNaN(deltaP)) { alert("Please enter valid numerical values for all fields."); return; } if (thickness <= 0) { alert("Thickness must be greater than zero."); return; } // Calculation: OTR = (P * deltaP) / L var otr = (p * deltaP) / thickness; // Formatting result to 4 decimal places or less if not needed var finalResult = Number(otr.toFixed(4)); valueDisplay.innerHTML = finalResult.toLocaleString(); resultDisplay.style.display = 'block'; // Smooth scroll to result resultDisplay.scrollIntoView({ behavior: 'smooth', block: 'nearest' }); }

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