Home made water pressure/depth test

I was thinking about the low pressure water resistance tests which some people perform. This usually entails a sink, bathtub, and occasionally the deep end of a pool. This is all fine and dandy for most uses, but what about the more robust lights which should be able to handle much, much more?

So, I thought of a more extreme water resistance pressure test. But first, there is just one point I need to make clear:

**WARNING, DO NOT ATTEMPT THIS AT HOME**

Okay, now with that out of the way, this is how you attempt it at home.... :devil:


Take your average 2 liter soda bottle (preferably clear) and remove the wrapper. Turn on your light, drop it in, drop in a handful of dry ice chunks, fill it about half way full with FILTERED water (very important it's filtered), and quickly and cap it off. Set in a safe place where the impending will be safely contained.

Now, what good is this other than being extremely entertaining??

Well, as most people know, putting dry ice (frozen CO2) and water in an enclose container builds up pressure and explodes. In your typical 2 liter soda bottle, the minimum rated burst pressure is 150psi. So even though you only put a few inches of water in it, the increased pressure mimics deeper depths. Just how deep? Well, 150 psi is equivalant to 312 feet deep in salt water or 346 feet in fresh water.

Why filtered water? Well, if the light does leak, that doesn't mean it's doomed to die. Contrary to popular belief, water doesn't fry electronics, it's the minerals dissolved in water which make it dangerous to electronics. If the light does leak, you simply have to dry it out and it should work again. Filtered water minimizes the risks of permanent damage.

Couple key notes:
1) Keep in mind that the light may go flying. Might want to tie an orange lanyard onto it.
2) This is extremely dangerous and loud, plan accordingly.
3) Not responsible for any permanently damaged lights.

Maybe a hand held pump and a air tight bottle could be a more precise and safe solution?

The burst pressure of a 2 liter soda bottle is a pretty inexact measurement. Since the bottles are built to a minimum standard it could actually be higher than that. Also, I don't know that I would want to subject some of my lights to an explosion just to see if a light was waterproof to a depth that I could never go to. If you find yourself at 300 feet under water you've got bigger problems than whether your light is working. ( unless you are a professional diver, who would only use a real dive rated light made for scuba diving ) Most swimmers don't go deeper than 10 feet, most snorkelers don't go deeper than 30 feet, and most recreational divers don't go below 150 feet.

I was thinking about this the other day watching that episode of myth busters....
-Plastic mayonnaise jar
-unflavored seltzer water
-Mentos mints

Fill jar with soda water. Place light in water, turn on. Drop a mentos in and quickly cap it up. Watch the sparks fly!!

Hardly a way to accurately measure anything... You'd have to rig up a pressure gauge to the jar.

In the world of watches they test waterproffness by putting the watch in a glass of water. Then they stick it in a vacuum chamber and suck the air out. They do this to test the seals around the back, crystal, and buttons/yolks. Thus instead of water getting into a watch mechanism and messing things up any "bubbles" that you would see is a weak area that needs to be looked into and fixed.

Now a vacuum chamber can be made with a few component one can find at a science shop. Vacuum pump, bell jar, platform big engough to cover the edges of the bell jar and a small container to cover the test item in water. This would be a very safe way to test lights and not worry about the water getting into electronics.

Wouldn't it be easier to use a pressure-cooker?

piece of pvc, a pressure regulator, a cap, as well as a screw on cap. glue the cap,and thread ring on, install a air coupler fitting.

in for video..

GPB said:

.......................If you find yourself at 300 feet under water you've got bigger problems than whether your light is working. ( unless you are a professional diver, who would only use a real dive rated light made for scuba diving ) Most swimmers don't go deeper than 10 feet, most snorkelers don't go deeper than 30 feet, and most recreational divers don't go below 150 feet.

Click to expand...

Even if you do not go deeper than 5 feet you still need a light that can handle 10 times or more to be water resistant. Because as you move in water or the light hits things under water it increases water pressure dramatically.

This is why watches are rated at a much deeper depth than what most divers would even dare go.