How does it differ from a thicker protective case?

A: The vent path. Extra thickness lowers deflection but the whole shell still takes the pressure, and the gasket opens first. A true explosion proof case gives up one designated face so the body survives. Check, on the sample, whether the vent is separate and its direction controlled.

May the vent face a walkway?

A: No. Point it outward, upward or into an empty area, away from doors and standing positions, and keep stacked cases and straps off it. An explosion proof case whose vent opens into a crowd works like a closed wall that cost money to install at all.

Can a plastic case serve as a containment shell?

A: Rarely on its own. Rotomolded polyethylene carries handling loads better than pressure, so it usually takes the relief route, with metal reinforcement where needed. A containment claim belongs to the structure of the relevant level, not to wall thickness, and to the report behind it.

Why does fastener spacing matter?

A: Fasteners clamp the gasket and break the joint into short spans. Too wide and the lid lifts between them, unloading the seal in the middle. An explosion proof case spaces them 200 to 300 mm, tightening beside the vent rather than adding more of them. ---

What an Explosion Proof Case Is: Relief, Containment, Strength

Quick answer: An explosion proof case is a rotomolded shell arranged around pressure from inside, not a sealed box with a heavier lid. Three routes exist: relief, which lets overpressure out through a designated face; containment, which carries the load in thick walls and narrow joints; intrinsic safety, which limits energy before it reaches the shell. Four details carry the design: wall and ribs, vent direction, joint form, fastener spacing. All four can be measured at goods-in.

Definition: a direction first, an outline second
Three routes: the load lands in different places
Four details: wall, vent face, joint, fasteners
Inspection: four moves at the goods-in desk
Order of judgement: from duty back to dimensions
FAQ

1. Definition: a direction first, an outline second

An explosion proof case starts from a direction, not an outline. Three answers come first: which face may vent, where it points, and what sits in that path. Wall, joint and fastener layout follow; the shell shape is only their result.

Open case, thick twin wall and vertical ribs

Two cases can share an outline and share nothing else. Look for the vent path: a separate panel, an opening disc, a band of controlled thin wall. An explosion proof case without that path is a thick protective box wearing the name.

Route	What carries the load	Shell-side focus	Where it fits
Relief	one face opens first	vent area, direction, fasteners	brief pressure, controlled position
Containment	shell and joints take all of it	wall, joint length and gap, bolts	flame stays inside
Intrinsic safety	the shell carries nothing	isolation, marking, bonding	energy limited upstream

2. Three routes: the load lands in different places

Relief gives the load to one face that opens near a set value. Containment keeps pressure inside and cools what escapes through narrow joints. Intrinsic safety limits energy upstream, so the shell only isolates. Routes can stack, but they never cancel.

A rotomolded case sits mostly on the first route. Twin polyethylene walls take handling loads well and pressure poorly, so the vent must be hardware, not a drawing note. Block it with a divider and the explosion proof case loses its only exit.

3. Four details: wall, vent face, joint, fasteners

In an explosion proof case, wall and rib set deflection. A twin wall runs 6 to 10 mm, plus a millimetre at rim and base. Ribs stand 15 to 25 mm at 150 to 200 mm centres, roots radiused at 8 mm, because a square root starts the crack.

Vent disc and stainless draw latch on the side

The rest is placement. The vent faces outward or upward, clear of walkways and strap rails, at 15 to 25 percent of the side. Joints are stepped tongue-and-groove, gasket compressed 25 to 35 percent, fasteners every 200 to 300 mm.

4. Inspection: four moves at the goods-in desk

Four checks at goods-in: wall at rim and rib root, fastener spacing, joint gap with the lid shut, vent travel by hand. A wall a millimetre under drawing or a 0.3 mm feeler in the joint sends the explosion proof case back.

Two cases side by side in a storage room

Treat the vent as its own item. It must be separate and never covered by a divider, strap or nameplate. Where a rating matters, the explosion proof case is built to the structure of the relevant level, and the third-party report is the evidence.

5. Order of judgement: from duty back to dimensions

Selection runs backwards. Fix the highest pressure the contents could raise, size the vent from it, place fasteners, then set wall and rib for handling and stacking. Reverse it and the vent faces a wall or sits under another case.

For dust and rain alone, a protective case is lighter and cheaper. Where a short fault can raise pressure and the position is uncontrolled, the explosion proof case needs a relief route. Three tests decide: source, direction, records.

Conclusion

For an explosion proof case, read it in one order: find the vent path, measure wall and fastener spacing, then confirm nothing covers the vent. The order cannot be shuffled. Without a path, thickness is only weight; with the path blocked, tighter spacing has nowhere to push. Leave the rating to the report, and check that the route stays clear. Drawing against sample is the comparison you own.

This article covers container-side specifications and design implications only, not the handling, loading or use of the contents.