DIY Canister Light Depth Testing

[MrSpock]

So I almost finished my project:
- 4 x Cree R2 LED Serial with reflectors and lenses
- Buck 1000 mA driver
- DIY 14.8 Li-Ion battery
- 3 inch schedule 80 pipe canister
- Modded 3D Mag-light head
- Mod a Mag heat sink

All works fine on my desk. Now, the question is: how to properly depth test it? I'd like to have piece of mind on at least my max depth plus 10-15% - 150 ft at least.

Some ways I thought about:
- Go diving: easy, but can't test it enough. Only the operating depth.
- Tide it to a 150 ft rope and lower from the boat: good idea, but I don't have a boat.

Any other options? How people usually test their lights?

 

[nwbrewer]

I brew beer, so for my initial depth test I threw it in a Corny keg and hooked up the gas to 50psi. After that I've dove to to around 130 with no issues. Some people have made more sophisticated pressure pots from old condemned Al80s and 1" plexi.

 

[heffay]

My canister is just BARELY too big to fit in my Corny keg :(

 

[H20doctor]

Building a pressure tank is very easy.. I built mine out of 4inch ABS ... Tapped it for a stainless tire valve stem, and a pressure guage.. The top uses a slip to thread coupling that I tighten with a 4 inch thread cap... Simply put your computer in the bottom, fill with water, seal , and pump her up with air... You could get bigger diameter such as 6 inch abs at any Plumbing company ...

 

[heffay]

FYI, low pressure inflator adapter to NPT fitting

http://www.divegearexpress.com/regulators/adapters.shtml

 

[MrSpock]

FYI, low pressure inflator adapter to NPT fitting

http://www.divegearexpress.com/regulators/adapters.shtml

Good find, thanks Heffay! Now I guess I need a Corny keg and some plumnbing...

Oh man, I'm afraid my wide will kick me out if I bring a Corney keg home. I don't have a garage and am doing all my work on the computer desk. I guess I can say it's a decoration of some kind ;-)

 

[heffay]

If you acquire a Corny keg, you might as well start brewing some beer too ;-)

 

[Packhorse]

I use a keg too.

But you dont have too. If its going to leak it will leak in a bucket.

If you fear it will implode. Dont.
The weakest link in the head is the lens. I used a stock mag lens to 42 meters before it went concave and smashed a MR16 halogen. It didnt leak.
I now use 4mm perspex and its been to 55meters several times. I think its would be good to 100 meters.

 

[MrSpock]

I use 3 mm glass front lens - it should be fine. But I'm worry about plastic glands (although IP68 approved), canister latch screws, and canister o-ring, since the lid surface isn't 100% polished.

 

[Packhorse]

I use 3 mm glass front lens - it should be fine. But I'm worry about plastic glands (although IP68 approved), canister latch screws, and canister o-ring, since the lid surface isn't 100% polished.

Is the glass tempered? or just standard glass?
3mm glass is probably only rated to 30 meters or so (maybe less). In saying that i used 2x 1.66 pieces of glass from DX and had it in a pressure to to 50-60 meters

I have used a variety of glands. None have leaked.
IP68 means water proof to 1 meter for 1 minute of something.
If you want to be confident in them get IP68-10 bar
I cant see the screws failing under pressure ( unless you have drilled them right through in to the can) and as for the O ring its more likely to leak in a bucket than at depth. The greater the external pressure then more the lid will be pushed closed compressing the O ring more.

I'd just go find the deeped water you can eg off a jetty, wharf etc and tie it to a bit of string with no batteries in it. If it does not leak there it will be OK.
(Its always nerve raking the 1st time)

 

[MrSpock]

I bought a 5-Gal (20 Litres) Cornelius Keg! It still smells like Pepsi! My light #2 didn't fit thru the opening - so I widened it a bit. Will be testing both lights over the weekend. Target depth: 150 Ft/46 M (82 PSIG/5.6 BAR).

 

[MrSpock]

Test succeeded! Both lights survived 3 "dives" to 150 ft, 10 minutes each. So, simple Mag mods aren't bad after all.

 

[gav6280]

Can i just mention that building your own pressure test pot is very dangerous! If there is any air space at all left in it and you over pressurise it, you basically have a bomb.

Why not just take it to your local dive shop, they will probably do it for free if you talk to them nicely and explain what your doing, they will likely been very interested. It worked for me.....

 

[MrSpock]

Dangerous indeed, as scuba diving, skiing, motorcycling, backpacking, etc.

The Cornelius Kegs are rated for 130 PSI of air, I tested lights at 82 PSI. I kept about an inch of air there just to keep my manometer working. So if it decided to go -boom- it would be a very small -boom-. More like -psssss-.

I asked my LDS, but unfortunatelly they have a very small pressure pot. They test watches and computers there. Other place I asked was a store specialising in underwater photo/video equipmnet. They asked $35 for every test - exactly the price I paid for the keg.

 

[Packhorse]

That is a good point about air spaces in test pots. But as Spock pointed out , Kegs are rated for reasonably high pressure.

As it is I only ever pressurise mine to about 3 bar (4 bar absolute) as this is the limit of our water pressure. I dont think you really need extreme pressures to test for leaks. You do if you want to test the strength of components though. But then you should be testing them at pressures twice what you will be exposing them too and for me that means over 10 bar. I am unsure of what my keg is rated to.