Pressure Equalisation Valves Explained
A pressure equalisation valve lets air move in and out of a sealed case so the internal and external pressure equalise. It solves vacuum lock — a warm case cooled quickly develops a partial vacuum that makes the lid hard to open and pulls outside air, with its dust, through the seal the moment you crack it open. It is not a waterproofing device.
Key points
- The valve addresses pressure differential, which is a different problem from liquid exclusion.
- A valve is a membrane path: it must be rated for the exposure you expect, and it is a component that can fail.
- Cases that fly, or that move between air conditioning and open sun, benefit most.
- If you never open the case in dusty or wet conditions, you may not need one.
When to specify one
| Situation | Need |
|---|---|
| Air cargo or cabin movement | Yes — pressure change is guaranteed |
| Hot vehicle to air-conditioned room | Yes — the vacuum lock is immediate |
| Depot shelving, stable temperature | Usually not |
| Marine or immersion exposure | Only with a valve rated for it; otherwise a weak point |
Applications
This matters most where the case is part of a movement chain rather than shelf packaging. In outdoor & recreation and aerospace & avionics the same shell is specified differently because the handling, the environment and the verification requirement differ.
- Outdoor & Recreation — Consumer and professional outdoor brands buy cases as a component of their product. That means c…
- Aerospace & Avionics — In aviation ground support, the case is part of the tooling chain and its mass is a direct cost.…
Customisation
Everything described above is configurable on a standard shell: interior layout (pick-and-pluck, die-cut or CNC-cut), foam grade and thickness, colour, logo method, latch and lock count, pressure-equalisation valve, cable ports, document holder and identification plate. A bespoke exterior geometry requires a new mould — 125 days, from 3,000 units per moulded component.
Procurement considerations
| Question | What to send us |
|---|---|
| Which shell fits? | Equipment L × W × H as packed, plus required clearance per axis |
| What does it cost? | Order quantity and estimated annual quantity — the two drive different answers |
| Is tooling needed? | Whether an existing shell clears the envelope with usable foam depth |
| Lead time? | Your required delivery date, not just the order date |
| Certification? | The exact standard your tender names — we will say whether we can test to it |
| Freight? | Destination and preferred terms; carton and pallet data supplied with the quotation |
Comparison and selection guide
The tables on this page exist because a protective case is chosen by comparing three things: the envelope, the environment and the handling chain. Where no table applies, the rule below is.
| Situation | What To Do |
|---|---|
| Occasional splash | A close-fitting rim without a gasket is cheaper and easier to maintain. |
| Rain and washdown | Sealed configuration, four or more latches, stainless hardware. |
| Immersion or pressure change | Sealed configuration plus a pressure-equalisation valve, and a documented test. |
- Size on internal dimensions plus clearance, never on a product name.
- Choose the carrying method before the shell: it changes the series, not just the price.
- Specify the interior last, and decide up front whether the end user will reconfigure it.
Pressure Equalisation Valves Explained relates to Waterproof & Dustproof Guide. Related families: Waterproof Cases / Outdoor Protective Cases. Related sectors: Outdoor & Recreation / Aerospace & Avionics. Continue in the Waterproof & Dustproof Guide cluster.
This page is written from our own production data. If your requirement differs, send the dimensions and we will tell you which of the 155 models fits, or whether a custom route is needed.
