Refrigerated Transport (Reefer) MKT Calculator

Reefer (refrigerated transport) loads are carried to a setpoint matching the product's storage condition; door openings at multi-drop stops and defrost cycles create the warm excursions MKT assesses. The authoritative limit is whatever your product's labelled storage condition and stability data specify — read it off the marketing authorisation, the manufacturer's storage statement or the governing pharmacopoeia, and enter your real temperature history against it.

Usually not on its own — that's precisely what MKT is for. Each door-opening at a delivery stop briefly warms the load before the unit recovers; across a multi-drop route these add up, but if the MKT over the whole journey stays within the product limit, the load is compliant. Map the temperatures and durations (the reefer's own logger or a load logger) into this calculator. Watch instead for a sustained warm period (a unit breakdown, a setpoint error, or a long delay) that drives the MKT over the limit, or any product-specific hard ceiling. Pre-cooling the load and the box, and minimising door-open time, keep the MKT comfortably in range.

Because degradation is not linear with temperature — it accelerates roughly exponentially (Arrhenius). A simple average treats an hour at 30 °C the same as an hour at 20 °C either side of 25 °C, but the product is harmed far more by the hot hour. MKT weights each reading by exp(−ΔH/RT), so it reflects the true cumulative chemical stress. It is always ≥ the arithmetic mean, and it is the figure regulators expect for storage and distribution compliance.

Use a representative series with durations — typically the logger's interval readings, or summarised blocks of 'X hours at Y °C' if you only have an excursion summary. The more granular the data, the more accurate the MKT, but the result is dominated by the warm excursions, so capturing those accurately matters most. Don't average data before entering it — that defeats the point; enter the temperatures and let the calculator do the kinetic weighting.