light question?

[mako1]

why does every one use mag light bodies and cut them and grind them and force o-rings in them just to make them water tight? i was thinking of useing a pvc union (which has a oring in it) and pipe for the hand unit. Just put the light bulb reflector in the union. I'll get pictures and details over the weekend, but is there some other reason like heat? any help mike

 

[Diver0001]

why does every one use mag light bodies and cut them and grind them and force o-rings in them just to make them water tight? i was thinking of useing a pvc union (which has a oring in it) and pipe for the hand unit. Just put the light bulb reflector in the union. I'll get pictures and details over the weekend, but is there some other reason like heat? any help mike

I've seen lights built like that. Heat from the lamp seems to be the biggest concern. PVC melts and/or becomes quite soft at relatively low temperatures.

R..

 

[MarkH]

I've seen lights built like that. Heat from the lamp seems to be the biggest concern. PVC melts and/or becomes quite soft at relatively low temperatures.

R..

I have one like that made out of PVC. The end is one of those PVC threaded "caps" with an o-ring already in it. The lens is a piece of plexi-glass glued to the front. I use a 50w halogen bulb in it and most people in the know would say that the heat would blister or at least warp the plexi-glass, but I use mine for video and the longest I have it turned on is around 30 seconds. -So far (a year or so and maybe 40 dives with it), no problems.

 

[Gary D.]

It's not a problem no matter how long it is on or the wattage as long as the light is submerged. Out of the water it will melt.

Also remember to put the reflector tight against the lens.

Gary D.

 

[oxyhacker]

Not necessarily. Steve, while he was working on the divelight book, melted several PVC lightheads using 36 to 50w halogen bulbs, and melted some acylic lenses with 50W halogen bulbs, despite being submerged. The lamp base and socket radiate a lot of heat, and if they are too close to the PVC will start to char it water or no water.

There's a lighthead in the book built around a 1" PVC pipe union, which, with a little work, will perfectly fit an MR16 bulb, but it won't reliably handle over 20W.

Might be good for HID, though........

It's not a problem no matter how long it is on or the wattage as long as the light is submerged.
Gary D.

 

[Gary D.]

Not necessarily. Steve, while he was working on the divelight book, melted several PVC lightheads using 36 to 50w halogen bulbs, and melted some acylic lenses with 50W halogen bulbs, despite being submerged. The lamp base and socket radiate a lot of heat, and if they are too close to the PVC will start to char it water or no water.

There's a lighthead in the book built around a 1" PVC pipe union, which, with a little work, will perfectly fit an MR16 bulb, but it won't reliably handle over 20W.

Might be good for HID, though........

I've been using these for years on both video and drop cameras with no melts up to 100 watts. Even 3 hours of being on have never melted a lens or housing. 35 to 50 watts seem to work best for video.

In tests a 50 watt bulb raised the water temp in the kitchen sink from cold tap water to 80 degrees in 1 hour but has never melted a 1/2" plexiglass lens. The trick here is to have the bulb and it's reflector against the lens.

http://www.mswobbles.com/submersible/index.html

Some of the off the shelf dive lights are a lot hotter with a lot thinner lens and don't have any problems as long as they are submerged. Out of the water they will fry the lens and in some cases the body as well.

Gary D.

 

[mako1]

I've been using these for years on both video and drop cameras with no melts up to 100 watts. Even 3 hours of being on have never melted a lens or housing. 35 to 50 watts seem to work best for video.

In tests a 50 watt bulb raised the water temp in the kitchen sink from cold tap water to 80 degrees in 1 hour but has never melted a 1/2" plexiglass lens. The trick here is to have the bulb and it's reflector against the lens.

http://www.mswobbles.com/submersible/index.html

Some of the off the shelf dive lights are a lot hotter with a lot thinner lens and don't have any problems as long as they are submerged. Out of the water they will fry the lens and in some cases the body as well.

Gary D.

thanks for aii the info. i will try to finish the light head this week ( this weekend was a bust 70 degrees and sunny, i was outside all weekend) maybe it will rain one night. my plan was to use a 1.5" union with a o-ring and a glass lens, i run it in the sink and see how it does heat wise. Gary your light looks very close to my idea, i should have know somone had this idea 1st. mike