How much should a portable plastic carrying case hold?

Answer: Under 13 kg for hand carry, 18 kg for a sling, under 10 kg for cabin use, with shell and liner subtracted first.

Can one case serve hand and shoulder carry?

Answer: Yes, but anchors must suit the sling; under 60 mm apart, webbing presses on the saddle and rivets loosen first.

Does IP67 make a case suitable for cabin carry?

Answer: Not by itself. IP67 covers dust and short immersion only, and a unit above 115 cm goes to the hold regardless.

Is a whitened handle root still usable?

Answer: Whitening is an early stress signal; strength remains until a crack opens. Stop loaded long-distance carrying and raise the fillet next order.

What if the sum of sides is two centimetres over?

Answer: Trace the protrusion. Recessed wheels or a flush handle usually recover 20 to 25 mm without a new mould.

How is foam density decided?

Answer: From the heaviest single item. At 25 kg/m³ the liner suits manual handling; above 3 kg per item, 35 kg/m³ holds better at 0.2 kg extra.

Portable plastic carrying case: hand, shoulder or cabin carry

Quick answer: A portable plastic carrying case is judged by how it leaves the ground. Hand carry, shoulder sling and cabin carry fail at different points, so weight ceilings, envelope limits and load paths cannot be swapped between them. Fix the carry mode first and every later figure becomes comparable.

Three Carry Modes and the Clauses That Apply
Total Weight: Case, Liner and Load Margin
Outer Envelope: Sum of Sides and Cabin Limits
Handle and Shoulder Strap: Where the Load Lands
Three Field Checks and a Verification Sheet
FAQ

1. Three Carry Modes and the Clauses That Apply

Two portable plastic carrying case units can share one shell drawing yet need different structures: one is swung by hand for two hundred metres, the other pushed into an overhead bin.

Carry mode	Loaded weight	Envelope control	Clause worth reading
Hand carry	9–13 kg	Handle near centre of gravity	MIL-STD-810H Method 516.8
Shoulder sling	12–18 kg	Strap anchor height	IEC 60529 dust rating
Cabin carry	7–10 kg	Sum of sides, wheel protrusion	Airline cabin envelope

Read standards down to the method number. Method 500.5 covers low pressure at 4,572 m; Method 516.8 covers shock severity. Under IEC 60529, IP67 means one metre of water for thirty minutes, while IPX5 is only a jet spray, so gasket demands differ by a full grade. The drawing must carry the full envelope, handle, wheels and latches included.

2. Total Weight: Case, Liner and Load Margin

Weight is where a portable plastic carrying case comparison goes wrong. Rated load states what the shell holds, not how long a person carries it.

Portable plastic carrying case: light grey open case on a wooden pallet, black foam insert, folding front handle, stacked cartons behind

Element	Reference	What it changes
Empty shell	2.6 kg	Two shells of one size differ 0.7 kg in ribs
Liner	0.4 kg	25 kg/m³ foam lightens once pocketed
Equipment	0.8–2.5 kg	Pocket depth follows the heaviest item
Hardware	0.3 kg	Anchors, rivets and webbing add up

Keep the loaded total at or under 13 kg and a one-hand carry stays steady for ten minutes; above that, widen the sling webbing to 38 mm so pressure moves to the shoulder. It is a field line, not a standard, but applying it to every sample keeps a comparison honest.

When the figures do not fit a portable plastic carrying case, drop equipment first, step down a shell size second, and consider wheels last.

3. Outer Envelope: Sum of Sides and Cabin Limits

Envelope decides whether a portable plastic carrying case clears a cabin door, and measuring is where errors enter.

Sum of sides: length, width and height together at or under 115 cm;
Handle protrusion: a folded handle still stands 18 mm proud;
Wheels: exposed wheels add 22 mm in diameter, recessed ones take it from internal volume;
Latches and feet: lid latches stand 6 mm proud, four feet take 4 mm each.

Run the tape flat, press over ribs rather than bridging them, and record the largest reading.

4. Handle and Shoulder Strap: Where the Load Lands

Handles fail at the load path rather than in the material, which is why one resin cracks in one mode and survives another.

Portable plastic carrying case: grey case standing on a warehouse pallet, recessed top handle, scuffed lid, cartons and tool racks behind

On a hand-carried unit the load concentrates at the two roots of the handle saddle, where 4.5 mm of wall and an R3 fillet resist cracking. On a sling unit the load shifts to side-wall anchors, where webbing passes through a metal D-ring, with 8 mm webbing and five backstitch rows holding tension evenly. On a cabin unit the case is shoved into a bin, so the load lands on lid edges and corners, which want a double wall. Before accepting a sample, load it, walk two hundred paces, cycle the latches thirty times, and check the handle roots for whitening. Whitening marks stress concentration rather than cosmetic wear. Sling versions need a look at the anchor rivets, since a poor rivet lets webbing tear from the hole edge.

Cold sharpens the point on any portable plastic carrying case: two hours at minus 20 °C lowers toughness, and an identical load cracks the same root sooner.

5. Three Field Checks and a Verification Sheet

No instruments are needed to screen a portable plastic carrying case on site: lift it empty, walk it loaded, cycle the latches.

Check	Pass line	How to record
Empty lift	Lid flat, seam aligned	1.5 mm feeler gauge
Loaded walk	No whitening after 200 paces	Photo on file
Latch cycling	No self-release after 30 cycles	Tally sheet

One cheap extra check: press the four corners of the open lid. A creak means the panel lacks stiffness.

Conclusion

Comparing a portable plastic carrying case means fixing the carry mode, then aligning weight, envelope and load path against it. The three thresholds do not transfer. Write loaded weight, sum of sides and handle wall thickness as three measurable figures, and the decision stops depending on feel. Once the field checks are done, most samples answer for themselves.

This article discusses only the container (case body) side of specifications and design intent, and does not cover any handling, loading or use of the contents.