Reefer semi-trailers and refrigerated bodies at a glance: body types, insulation and K value, ATP classes FNA to FRC, certificate validity, refrigeration units and buying used.
A reefer semi-trailer carries whatever needs temperature control: fresh produce, deep-frozen food, meat, pharmaceuticals. Its value is determined not by payload but by the insulation, the refrigeration unit and one piece of paper: the ATP certificate. Which body types exist, what the class letters mean, which units are fitted and what to look for when buying and selling.
The reefer semi-trailer is a semi-trailer with a thermally insulated box body and a permanently installed refrigeration unit on the front wall. The body is made of sandwich panels: two skins with a foamed core in between. On the S.KO COOL, Schmitz Cargobull uses self-supporting Ferroplast panels; on the Cool Liner, Krone uses a thermal-bridge-free construction with a steel skin on both sides and CFC-free foam.
Insulation costs space and weight. For a double-deck Cool Liner, Krone states 13,310 mm of interior length and 2,630 mm of interior height, with a gross vehicle weight of 39,000 kg and an unladen weight of around 7,840 kg – leaving roughly 31,160 kg of payload, comparable to other semi-trailer types.
The standard solution in long-distance haulage: the largest volume, the highest payload, pulled by a tractor unit. The unit works independently of the towing vehicle with its own diesel engine and tank, around 240 litres at Krone.
A fixed box body on a chassis, typical for distribution transport. Spier builds such bodies for vehicles from 3.5 to 26 t and specifies wall thicknesses of up to 100 mm on walls and roof, designed for a constant −18 °C.
Rigid truck plus refrigerated drawbar trailer, often as a jumbo combination with through-loading; Spier lists bodies for trailers and through-loading combinations in its range. More volume than with a single vehicle, but two bodies and often two refrigeration circuits.
Panel vans with an insulated liner or a box body on a van chassis. The reserves are small: a data sheet for a 3.5 t panel van states 8.6 m³ of cargo space, four Euro pallets, −20 to +30 °C, ATP class FRCX and about 725 kg of payload.
Insulation performance is described by the heat transfer coefficient, in the ATP as the K value in W/(m²·K). The ATP recognises two levels: normally insulated equipment with a maximum of 0.7 W/(m²·K) and heavily insulated equipment with a maximum of 0.4 W/(m²·K); the testing body DNV defines “normal” as the range above 0.4 up to and including 0.7. For the Cool – PurFerro quality, Kögel specifies sandwich elements with a 0.6 mm steel skin and a polyurethane core. If moisture penetrates the foam core, the K value rises and the body loses its class – which is why the ATP prescribes a periodic re-test.
The ATP is the international agreement on the carriage of perishable foodstuffs, concluded in Geneva in 1970 under the aegis of the UNECE. According to TÜV SÜD, it governs the classification into classes, the requirements for thermal insulation and refrigeration equipment, the measurement methods and the transport temperatures for each foodstuff. The current version has applied since 1 June 2022.
The first letter stands for the means of cooling: F for a built-in refrigeration unit, R for a built-in cold accumulator. The second for the insulation: N normal, R reinforced. The third is the temperature class. An X is added if the compressor is driven by the vehicle engine or the refrigeration unit is removable – which is why many refrigerated vans carry FRCX rather than FRC.
Testing is carried out at a mean outside temperature of +30 °C. For adjustable temperature, the following applies:
There are also classes with a fixed temperature: Class D holds a maximum of +2 °C, Class E a maximum of −10 °C, Class F a maximum of −20 °C. In practice FRC dominates: TÜV SÜD describes it as the most common class, with which perishable foodstuffs within the meaning of the ATP can be carried without restriction. FNA is sufficient for chilled distribution, not for deep-freeze.
The certificate applies to a specific vehicle made up of body, insulation and refrigeration unit, not to a model range. In Germany, new certificates are issued exclusively by the ATP testing station, TÜV SÜD Industrie Service. For new vehicles it is valid for six years from the date of manufacture of the thermally insulated body.
After that the re-test applies: no later than six years after entry into service, then at most every three years. Body and unit are tested together – a visual inspection of the insulation and a cooling capacity measurement in which the unit must bring the empty interior down to the class temperature within six hours. If it passes, the certificate is valid for a further three years; otherwise a downgrade is possible. The document must be carried on board, and the class is shown on the outside of the vehicle in dark blue letters on a white background.
According to an ATP workshop in Germany, the obligation applies to refrigerated vehicles registered in Germany in international transport, and to foreign vehicles carrying chilled goods to Germany.
On rigid trucks and vans the vehicle engine often drives the unit as well: with Thermo King’s V series for cargo spaces of 5 to 54 m³, the separate diesel engine is dispensed with, and outputs are correspondingly lower – 2,080 W at 0 °C for the V-100 MAX, 7,790 W for the V-800 MAX. Frigoblock uses a three-phase alternator on the vehicle engine with an inverter; on trailers, AxlePower with the BPW ePower axle stores energy from rolling and braking.
Anyone carrying fresh and frozen goods in one trip needs compartments. Krone offers the Cool Liner Multitemp with up to three controllable compartments; the bulkhead can be moved along the entire body length and is itself ATP-certified, with an additional evaporator on the rear portal. Spier specifies up to four-compartment technology.
Double-deck loading creates spaces for non-stackable goods: Krone states 33 additional Euro pallets on the second level, on 22 aluminium load beams in twelve pairs of height-adjustable guide rails; for the SR2 series, Lamberet states 33 pallets on one level and 66 on two. Krone also supplies a flexible ceiling air duct for double-deck operation and a transverse bulkhead.
Schmitz Cargobull builds the S.KO COOL and manufactures its own S.CU refrigeration units. Krone offers the Cool Liner as a standard, double-deck, Multitemp and Meathang variant for meat transport, Kögel the Cool – PurFerro quality. From France come Lamberet with the SR2 family, including SR2 Heavy Duty and SR2 Super Beef, as well as Chereau.
Without a valid ATP certificate, the vehicle may not carry perishable foodstuffs in international transport. The buyer has to have the re-test carried out – with an uncertain outcome. The insulation is tested too: if the body has absorbed moisture, it may only qualify for a lower class, and an FRC becomes a vehicle without deep-freeze approval. A freshly renewed certificate, on the other hand, is a verifiable selling point.
Reefer semi-trailers are longer-lived than their reputation suggests. BPW cites twelve years as the usual service life; in a refurbishment programme, Chereau bodies with vacuum insulation panels passed the ATP FRC test even after twelve years, and the unit was cleared for a further six years. This second phase supports the used market – on the home market as well as in the export of used commercial vehicles, where age limits and import rules play a part.
Four factors determine the price: ATP class and remaining validity, operating hours and condition of the unit, condition of panels and doors, and equipment with double-deck and multi-compartment technology. A concrete figure for your vehicle is provided by the free valuation; after that, verified dealers from 35+ countries make binding offers – sell your trailer with truckoo.
F stands for a built-in refrigeration unit, R for reinforced thermal insulation with a maximum of 0.4 W/(m²·K), C for a temperature class between +12 °C and −20 °C. TÜV SÜD lists FRC as the most common class.
For new vehicles, six years from the date of manufacture of the thermally insulated body; after that, a re-test extends the validity by at most three years each time.
Body and refrigeration system together: a visual inspection of the insulation and a cooling capacity measurement in which the unit must bring the empty interior down to the class temperature within six hours.
The reefer semi-trailer is a semi-trailer with its own diesel-powered unit. The refrigerated box body is a fixed body on a rigid truck or drawbar trailer; its unit often runs off the vehicle engine or a generator.
For the S.KO COOL, Schmitz Cargobull states 33, 36 or 41 Euro pallets depending on length; with double-deck loading at Krone, 33 spaces are added on the second level.
From the operating hours: they say more about condition than the year of manufacture, because a unit also runs while stationary at the ramp.
Gabriel Böhm is Managing Director of truckoo GmbH, the digital platform that is redefining commercial vehicle trade in Europe. With a passion for innovation and efficiency, he shapes the strategic direction and drives operational excellence to connect sellers and buyers smarter, faster and more transparently.
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