The folder for the body opens with the ATP certificate: stamped, still inside its validity, nothing wrong with it on its own. What is usually missing on a two-compartment body is the second sheet that the certificate's own footnote asks for, the declaration of conformity, and on a truck running frozen in the morning and chilled in the afternoon the driver tends to find out at a roadside check that the file is complete only with both.
The ATP text itself asks for that sheet. Footnote 4, hung on the heading of the certificate model in Annex 1, Appendix 3 section A of ATP 2024, defines multi-temperature equipment and requires a declaration of conformity to travel alongside the ATP certificate, so the moment the box in the heading is ticked the file becomes a two-part file.
The box at the top and the calculation section use different words
Across the head of the model form sit the boxes INSULATED, REFRIGERATED, MECHANICALLY REFRIGERATED, HEATED and MECHANICALLY REFRIGERATED AND HEATED, and beside them a separate MULTI-TEMPERATURE box. Footnote 4 attached to that box describes multi-temperature equipment as insulated equipment with two or more compartments, each of them held at its own temperature.
The same body travels under another name where the arithmetic lives. Paragraph 7.1 (a) of Appendix 2 defines multi-compartment equipment as equipment having two or more insulated compartments, each kept at a different temperature. One word separates the two definitions: footnote 4 insulates the body, 7.1 (a) insulates the compartments themselves. The box on the certificate is ticked on multi-temperature grounds while the measuring and the sums are done on multi-compartment grounds, which is why the paperwork for such a body never stays in one piece.
What the second sheet actually says. The block headed "Conformity declaration" in section 7.3 of Appendix 2 states that the declaration is an additional document to the certificate of compliance issued by the competent authority of the country of manufacture, that it rests on the manufacturer's data and that it is drawn up on the Model No. 14 form. If nothing like it sits in your folder, ask the bodybuilder who sold you the unit or ask your supplier; for the Isotec equipment we bring in, we obtain the paperwork from GEBHARDT and pass it on to you ourselves.
Two items are named as the minimum content: a drawing showing how the compartments are really laid out and where the evaporators sit, and calculated proof that the multi-compartment equipment meets the ATP conditions for the freedom in temperatures and compartment sizes the user wants. That drawing is the description of the very body the declaration speaks about.
The same block also fixes when the calculation counts as finished. Every bulkhead position is treated as covered only if the positions from the smallest compartment up to the largest have been checked iteratively, in steps where the area changes by no more than 20%.
That lands on the run directly. Put the bulkhead somewhere outside the swept positions and the sheet in your hand stops describing the body you are driving. On a second-hand unit with no declaration at all, nobody can say in how many bulkhead positions and under which temperature splits the vehicle was ever proved against ATP; the certificate alone does not carry that information.
Both the paperwork and the test change once a second compartment appears, so our multi-temperature distribution page gathers how the regimes get shared out inside one vehicle.
The mark on the body repeats the same drawing
Appendix 4 says that road equipment divided into two compartments carries a mark built from the marks of both compartments, giving FRC-FRA as the example, and the compartment at the front or on the left is written first. Anyone reading the mark has therefore also read which end of the body belongs to which class.
Once there are more than two compartments the writing changes. Only the mark of the highest ATP class is taken, meaning the class that allows the largest difference between outside and inside temperature, and the letter M is added to it, which is how FRC-M comes about. This marking has been compulsory for all equipment manufactured from 1 October 2020.
The paperwork mirrors the body here as well. Under footnote 7, the "Is approved as" line of the model certificate is filled in with one or several of the descriptions from Appendix 4 together with the corresponding mark or marks; the plural is written into the form itself. A single class code on that line, on a certificate for a two-compartment body, is something worth asking about.
| What we look for | Where it is written | What it says about the run |
|---|---|---|
| MULTI-TEMPERATURE box | Appendix 3 section A, certificate model heading and footnote 4 | The body counts as multi-temperature, so a declaration of conformity travels with the certificate |
| Compartment and evaporator drawing | Appendix 2, "Conformity declaration" block (7.3.6) | Build the bulkhead differently from the drawing and the declaration no longer describes that layout |
| Step size of the calculation | The same block | Positions swept from the smallest compartment to the largest in steps where the area changes by no more than 20% |
| "Is approved as" line | Appendix 3 section A, footnote 7 | The line carries one or several descriptions from Appendix 4 with their matching marks |
| Composite mark | Appendix 4 | In FRC-FRA the compartment at the front or on the left is written first |
The periodic test measures the compartments at the same time. The "Multi-compartment equipment" (iii) block in section 6.2 of Appendix 2 requires the test prescribed in (i) to be carried out for all compartments simultaneously. Where the bulkheads move, compartment volumes are set so that they correspond to the highest demand for cold, and the measurement runs until the warmer of the two sensors placed inside each compartment comes down to the class temperature.
Nothing is softened on the timing either. The body passes only if every compartment reaches its class temperature within the time read from the table in (i), and that time is chosen using the lowest, meaning the coldest, of the two mean outside temperatures recorded by the two external sensors. Taking the colder reading builds the test on the harder of the two figures.
For bodies whose compartment temperatures can be changed, the same block adds a reversal test. The settings are chosen so that neighbouring compartments sit on different regimes as far as possible: some are brought down to the class temperature of -20 °C, others are held at 0 °C, and then the settings swap places.
What is being watched is the regulation itself. Compartments that have moved to 0 °C are required to hold 0 °C ± 3 °C properly for at least 10 minutes while their neighbours stay at -20 °C; the settings are then reversed once more and the same check is repeated.
Here the two builds part company. On a body with a heating function the test begins after the efficiency test at -20 °C and runs with the doors kept shut and no limit on time. On a body without heating, the compartment doors may be opened to bring the temperature up faster, so the same procedure plays out in two ways depending on the equipment.
The same section 7 also describes a compartment with no cooling of its own. Paragraph 7.1 (d) defines an "unconditioned compartment" as one that, for the purposes of dimensioning calculations and certification, is considered to have no evaporator or an evaporator that is not running, and in the sums it enters at +20 °C: the block "Determination of the refrigerating demand of chilled evaporators" (7.3.3) applies +20 °C to unconditioned compartments, while the neighbouring block "Determination of the refrigerating demand of frozen compartments" (7.3.4) applies the same +20 °C to insulated compartments. The reading that follows is ours: in ATP arithmetic a compartment like that counts as no second cold zone, it presses on the other side of the bulkhead as a +20 °C load. The second regime there has to be built by whatever you load into it and evidenced by that equipment's own data, whereas a second evaporator in the body ties you for good to the bulkhead positions and temperature splits already calculated in the declaration of conformity.
