Can an en 45545 case cover only R22 or only R23?

A: It depends on hazard level: at HL1 the exposed parts usually stand alone, while HL2 and HL3 need both sets.

Is a 32% oxygen index just a matter of adding more retardant?

A: No. Around 8% loading reaches 28%; beyond that the system changes. Pushing to 12% may give 31% but costs 8%–12% of tensile strength.

Smoke limits differ by a factor of two, so can everything be run to 300?

A: No. Internal parts are judged at 150, and data run against 300 is rejected as not applicable.

Does a 3 mm specimen represent a 4 mm wall?

A: It does, if the compound and moulding route match and the report states the thickness. If the buyer insists, one supplementary set at 4 mm settles it.

Is V-0 the same as an oxygen index?

A: No. V-0 looks at afterflame time after the small flame is removed and at whether drips ignite cotton; oxygen index is the minimum concentration that sustains burning.

EN 45545 Case: R22 vs R23

Quick answer: An en 45545 case is judged R22 for exposed parts over 0.25 m² and R23 inside; typical limits run 28%/32% oxygen index and 300/150 smoke, graded by HL.

Two Questions Decide the Requirement Set
Oxygen Index and the Four-Point Gap
Smoke Density, Peak Heat Release and Toxicity
Hazard Level Picks How Many Sets You Run
Specimens, Area and Thickness
FAQ

1. Two Questions Decide the Requirement Set

A cover panel with 0.42 m² of exposed face and the divider behind it come from one moulding family, but not from one requirement set. Under EN 45545-2 the panel is normally R22 and the divider R23. R22 addresses equipment and cases mounted outside the vehicle or on exposed faces; R23 addresses in-vehicle equipment and internal parts. Final classification follows the vehicle hazard level and the mounting position.

R22 usually covers shells, covers and door skins; R23 covers brackets, dividers, liner panels and latch seats. They are not a high and low pair: R23 is typically stricter on index, R22 looser on smoke, and a mixed report fails review.

For an early call, one number helps: 0.25 m² of exposed area. Above it a part is usually read as external and taken to R22; below it, even an outside part is read as internal. A review that fixes the outline but not the area is one meeting away from a wrong set.

Requirement set and item	Where it applies	Typical requirement	Specimens
R22 oxygen index	Parts on or outside the vehicle body	≥28%, rising at HL3	3
R22 smoke density	Parts on or outside the vehicle body	Ds max 300, tighter at HL3	3
R23 oxygen index	In-vehicle equipment, internal parts	≥32%	3
R23 smoke density	In-vehicle equipment, internal parts	Ds max 150	3
Vertical burn, both sets	All parts	V-0	3

2. Oxygen Index and the Four-Point Gap

Air sits at 21% oxygen. A typical 28% index leaves seven points of margin before a flame sustains itself; 32% leaves eleven. Those four points cannot be bought with wall thickness, and which of the two applies depends on hazard level and position.

en 45545 case samples on a workbench, an aproned worker holding a wheeled black shell beside stacked olive and orange units

A halogen-free package at around 8% lifts a base resin from 24% to roughly 28%; more of the same additive stops working, and at 12% loading the index may reach 31% while tensile strength falls 8%–12%.

Preparation moves the number as much as the additive. The same compound pressed into a plaque and cut from a production wall can differ by 1–2 points, because fibre orientation and skin thickness differ. Cut specimens from a flat section of the actual en 45545 case, or the data will look good and fail on the assembly. Judgement runs on 3 specimens, 3 readings each, the lowest no more than 1 point under the threshold.

3. Smoke Density, Peak Heat Release and Toxicity

Smoke is judged on the maximum, not the average. Three specimens give three curves, the highest point across them becomes Ds max, and it is compared against the typical 300 for R22 or 150 for R23. One specimen over the line fails the set.

Heat release is read as a 90 s peak, because what escapes in the first 90 s decides whether people can leave. Specimens are tested flat at 3 mm; at 2 mm the peak reads 10%–15% low.

Toxicity is a separate index, typically CIT ≤0.9: smoke density is about seeing the exit, toxicity about walking to it, and a part can pass one while failing the other. Conditioning is the step most often skipped too, since specimens rested 48 h at 23 ℃ and 50% RH read 20–40 lower on smoke than ones taken straight from the floor.

4. Hazard Level Picks How Many Sets You Run

Hazard level belongs to the vehicle duty cycle, not to the case, but it decides how many sets the case has to cover and how tight each one runs.

en 45545 case cartons on a shrink-wrapped pallet, green epoxy floor with yellow aisle lines and workers packing at a conveyor

Rough mapping: metro and short commuter stock at HL1, mainline coaches and underground at HL2, sleeping cars and long tunnel sections at HL3. Sell one design to two operators and you run the stricter set, or keep two report packs.

Hazard level	Vehicle example	Sets run	Typical oxygen index	Typical smoke
HL1	Metro, short commuter	R22 mainly	≥28%	Ds max ≤300
HL2	Mainline coach, underground	R22 and R23	28% / 32%	≤300 / ≤150
HL3	Sleeping car, long tunnel	Both, stricter side	≥32%	≤150

All figures are typical requirements; a signed vehicle specification may add or relax one step and governs.

Higher levels add specimens and report pages, not necessarily a new shell; at HL3 the liner usually moves to a flame-retardant grade, adding 15%–20% to cost.

5. Specimens, Area and Thickness

Exposed area is projected area including folds and ribs, excluding shielded faces. A 600 mm × 400 mm cover projects 0.24 m², which looks under the line until the 40 mm return flange is counted, and then it clears 0.25 m² and moves to R22.

Cut specimens at least 50 mm from the gate and 30 mm from a weld line. Weld lines read 1–2 points low on oxygen index, so a specimen taken there reads low or scatters.

Specimen	Thickness	Exposed area	Requirement set
Lid outer panel	3 mm	0.42 m²	R22
Side wall panel	3 mm	0.36 m²	R22
Internal divider	3 mm	0.18 m²	R23
Latch and hinge seat	3 mm	0.05 m²	R23

All specimens are 3 mm so data stays comparable. A 4 mm production wall reads slightly higher on index and lower on smoke, but the report still carries 3 mm unless the buyer agrees to a supplementary run at actual thickness.

Conclusion

The logic for an en 45545 case compresses to one line: position first, then 0.25 m², then R22 at a typical 28% and 300 against R23 at 32% and 150, with HL3 on the strict side. Hazard level decides whether one set or two is run, and getting it wrong costs more than a pre-test.

This article covers case-side specifications only and does not address any handling, loading or use of the contents.