The Turn Screw Knob on Pelican Cases
If you’ve ever owned or seen a Pelican case (or other rugged waterproof protective hard case), you may have noticed a small screw-like knob near the main side of the case. Many people wonder: What’s this for? — It’s not a lock, and it’s not just decoration. It might look like a random piece of hardware, but it’s actually one of the most important features of the hard case when you are using it for your outdoor trip.
What It Is, Why It Matters, and How to Use It?
Let’s explore more in-depth here.
What the Turn Knob Actually Is
That little knob is not a latch or a lock—it’s a pressure equalizer valve, sometimes called a purge valve.
Pelican cases are built to be airtight and watertight, which is great for protecting your gear. But that also means air pressure inside the case can get trapped.
Why It’s Necessary
Pelican cases are designed to be airtight and watertight. While that’s excellent for protecting sensitive equipment from water, dust, and impact, it creates one problem: pressure differences.
When you take the case on an airplane, up a mountain, or anywhere the air pressure changes, the case can “suction shut.” Without the valve, it might be very hard to open.
- When you close the case at sea level and then take it to high altitude (on a plane or in the mountains), the pressure inside the case becomes greater than outside. This can make the case almost impossible to open.
- Similarly, if you seal the case in a high-altitude location and bring it down to sea level, the opposite happens—the outside pressure becomes higher, and the case can get “sucked in” tight.
Without the valve, your case could be extremely difficult to open—or worse, it could stress the seals and compromise waterproofing.
The knob solves this problem by allowing you to manually equalize air pressure without letting in water.
Why It’s Important
- Prevents stuck cases: Changes in altitude or air pressure won’t leave you fighting to open your case.
- Protects the seal: It avoids stress on the waterproof gasket, so your case stays watertight.
- Keeps it simple: You can quickly equalize pressure without compromising protection.
How to Use It
Using the knob is simple:
- Before opening the case after a flight or altitude change, twist the knob slowly counterclockwise to open the purge valve.
- You may hear a little hiss as air equalizes.
- Once the pressure stabilises (just a few seconds), twist the knob back clockwise to reseal it.
- Now you can safely open your case as usual.
A Note on Automatic Valves
Some Pelican cases have automatic purge valves that equalize pressure without needing manual adjustment.
Most protective hard case has the screw knob instead, It is simple and low cost that means it’s a manual purge valve—giving you more direct control.
Inside the knob sits a one-way membrane or vent that allows air to flow but keeps water and dust out.
Final Thoughts
That small screw knob may not look like much, but it’s a critical part of what makes Pelican cases reliable worldwide—from camera crews on mountaintops to military operations in the desert. It ensures your case stays both watertight and easy to open no matter where you travel.
So next time you spot that knob, you’ll know: it’s not just decoration—it’s the reason your gear stays safe and your case opens when you need it most.