Stereodude
Flashlight Enthusiast
Re: Diving with "The Moderator" - Part III added!
And, you can't forget that it shows he's offline.
Diving with "The Moderator"
- Thread starter DM51
- Start date
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Re: Diving with "The Moderator" - Part III added!
This is very sad!
This is very sad!
theamazingrando
Newly Enlightened
- Joined
- Oct 31, 2005
- Messages
- 184
Re: Diving with "The Moderator" - Part III added!
I, too, am intrigued to know what actual affect the voltage has on the problem. The galvanic reaction would occur between the two metals even if there was no current from the batteries, but I imagine the extra voltage serves as a catalyst.
I, too, am intrigued to know what actual affect the voltage has on the problem. The galvanic reaction would occur between the two metals even if there was no current from the batteries, but I imagine the extra voltage serves as a catalyst.
DM51
Flashaholic
Re: Diving with "The Moderator" - Part III added!
Part IV – my $0.02
Thanks to all for the interest shown, and for the kind expressions of sympathy for my (p)light.
In the last episode above, you will remember that reversing the battery polarity had resulted in the stainless steel tailcap rusting badly, and this had all but fused it to the Aluminium body of the light. I had decided to revert to normal battery polarity, although this would mean corrosion would resume eating away at the Al body instead.
Judging by the speed of the corrosion during the first 3 dives (total time a little over 2 hours), I doubted the Moderator would last another 2 weeks before it corroded almost completely away. I had to do something about that, if I could. Remember, I didn't know then what I know now about the chemical processes that had taken place. Nor did I know what remedy there might be, or even if there was one. I had to make a guess about what to do.
It seemed to me that the key was somehow to stop the electrolysis. Although it was a big waste of electrical energy, that was the least of the problems it caused. Far worse was the fact that it was producing sodium and chlorine ions along with the hydrogen and oxygen. I was sure these were somehow combining to form the acid that was causing the corrosion. If the electrolysis could be halted, or at least reduced, then the rate of gas and ion production would also be reduced, and in this way the corrosion might be slowed too. That was how I reasoned it, anyway.
I deduced that the electrolysis was occurring because the early stages of corrosion had formed oxides (or whatever) on the steel and Al threads, breaking the electrical contact between the two metals. Conduction had from then on been via the seawater, with its saline content completing the circuit. It was the current passing through the seawater that was causing the electrolysis.
If I could reinstate a physical metal contact between the body and tailcap, then the voltage between the tailcap and body would drop to zero, and the electrolysis should stop. What was the best way to make that contact?
There was a small gap between the tailcap and the body of the light, before the threads engaged with each other. The gap was about 1/10 inch (~2mm). The obvious thing to do would be to jam a piece of metal in there to make the required contact. I would scrape off some of the protective yellow paint to expose the bare Aluminium in that spot, and bridge the gap between that and the steel tailcap with some suitable metal object. What did I have that would make a really good electrical conductor?
Silver was the best conductor, I remembered. Looking back on it now, I think that if I had had a nice pair of silver cuff-links or some other fancy item, I would probably have willingly sacrificed them there and then to save this light. But I didn't have anything like that with me. The next best conductor after silver was copper. Maybe a piece of copper wire… but how would it be realistically possible to attach it and make it stay there?
A copper coin! That was the answer. It would need to be a small coin, to be jammed into that gap. I rummaged around in my bag. At the bottom were some coins, and among them was a British 1p piece. I tried it out. It looked as if it would fit OK, and could be hammered into place so it wouldn't fall out. I scraped away some yellow paint off the body so that the coin would be able to make a good contact with the bare Aluminium.
Reassembling the light with fully charged batteries, I pushed the coin into the gap and gave it a couple of good hard whacks with the back of my adjustable wrench to jam it in place. I tried the switch. Contact! The light came on! It worked! But what would happen during the dive? Would the copper cause an even more peculiar reaction?
I need not have worried. The dive went well – the Moderator seemed brighter than before, and although I could see a few bubbles coming off the contact areas near the coin, the effect was very much reduced from the rate I had observed before.
Here is a pic of the coin in place during that dive:
After the dive, I could see the coin had become coated with the same white material as the tailcap:
It was clear there was still a reaction going on, but on inspecting the previously pitted parts of the Al body, there had been no visible deterioration. Using the coin seemed to have helped.
Subsequent events proved the cure had worked. After each dive I removed the coin to open the light, and later, after recharging the batteries, I jammed it back in place again for the following dive. The corrosion of the Al body was brought almost to a standstill. I saw no more bubbles. The threads never jammed again. The Moderator continued to work perfectly.
Here you can see it hanging on a line from my surface marker buoy during a decompression stop at 6 meters, with one of its admirers photographing it.
By the end of the 2 weeks, the Moderator was looking a bit more battered – definitely well-used – but it was the toughest piece of equipment on that dive-boat. It had come through the test triumphantly. It is still working perfectly today.
As scottaw has said above, it was almost certainly the increased voltage and current that had led to the accelerated effect of electrolysis. With the stock low-power 4.5V bulb running on alkaline cells, this effect might only have been very slight, and possibly not noticeable at all. I rather wonder how these lights did actually perform with the British Royal Navy – did the Navy divers notice any problems with them after a while? Could that be why they were withdrawn from service and sold, with one of them ending up in my hands? It would be fascinating to know more.
Just one other thing to round off this tale: At the current rate of exchange, the 1p coin I used (UK £0.01) is almost exactly equivalent to 2 US cents.
So I can truthfully say - this story really is just my $0.02¢.
Thanks for reading it!
Part IV – my $0.02
Thanks to all for the interest shown, and for the kind expressions of sympathy for my (p)light.
In the last episode above, you will remember that reversing the battery polarity had resulted in the stainless steel tailcap rusting badly, and this had all but fused it to the Aluminium body of the light. I had decided to revert to normal battery polarity, although this would mean corrosion would resume eating away at the Al body instead.
Judging by the speed of the corrosion during the first 3 dives (total time a little over 2 hours), I doubted the Moderator would last another 2 weeks before it corroded almost completely away. I had to do something about that, if I could. Remember, I didn't know then what I know now about the chemical processes that had taken place. Nor did I know what remedy there might be, or even if there was one. I had to make a guess about what to do.
It seemed to me that the key was somehow to stop the electrolysis. Although it was a big waste of electrical energy, that was the least of the problems it caused. Far worse was the fact that it was producing sodium and chlorine ions along with the hydrogen and oxygen. I was sure these were somehow combining to form the acid that was causing the corrosion. If the electrolysis could be halted, or at least reduced, then the rate of gas and ion production would also be reduced, and in this way the corrosion might be slowed too. That was how I reasoned it, anyway.
I deduced that the electrolysis was occurring because the early stages of corrosion had formed oxides (or whatever) on the steel and Al threads, breaking the electrical contact between the two metals. Conduction had from then on been via the seawater, with its saline content completing the circuit. It was the current passing through the seawater that was causing the electrolysis.
If I could reinstate a physical metal contact between the body and tailcap, then the voltage between the tailcap and body would drop to zero, and the electrolysis should stop. What was the best way to make that contact?
There was a small gap between the tailcap and the body of the light, before the threads engaged with each other. The gap was about 1/10 inch (~2mm). The obvious thing to do would be to jam a piece of metal in there to make the required contact. I would scrape off some of the protective yellow paint to expose the bare Aluminium in that spot, and bridge the gap between that and the steel tailcap with some suitable metal object. What did I have that would make a really good electrical conductor?
Silver was the best conductor, I remembered. Looking back on it now, I think that if I had had a nice pair of silver cuff-links or some other fancy item, I would probably have willingly sacrificed them there and then to save this light. But I didn't have anything like that with me. The next best conductor after silver was copper. Maybe a piece of copper wire… but how would it be realistically possible to attach it and make it stay there?
A copper coin! That was the answer. It would need to be a small coin, to be jammed into that gap. I rummaged around in my bag. At the bottom were some coins, and among them was a British 1p piece. I tried it out. It looked as if it would fit OK, and could be hammered into place so it wouldn't fall out. I scraped away some yellow paint off the body so that the coin would be able to make a good contact with the bare Aluminium.
Reassembling the light with fully charged batteries, I pushed the coin into the gap and gave it a couple of good hard whacks with the back of my adjustable wrench to jam it in place. I tried the switch. Contact! The light came on! It worked! But what would happen during the dive? Would the copper cause an even more peculiar reaction?
I need not have worried. The dive went well – the Moderator seemed brighter than before, and although I could see a few bubbles coming off the contact areas near the coin, the effect was very much reduced from the rate I had observed before.
Here is a pic of the coin in place during that dive:
After the dive, I could see the coin had become coated with the same white material as the tailcap:
It was clear there was still a reaction going on, but on inspecting the previously pitted parts of the Al body, there had been no visible deterioration. Using the coin seemed to have helped.
Subsequent events proved the cure had worked. After each dive I removed the coin to open the light, and later, after recharging the batteries, I jammed it back in place again for the following dive. The corrosion of the Al body was brought almost to a standstill. I saw no more bubbles. The threads never jammed again. The Moderator continued to work perfectly.
Here you can see it hanging on a line from my surface marker buoy during a decompression stop at 6 meters, with one of its admirers photographing it.
By the end of the 2 weeks, the Moderator was looking a bit more battered – definitely well-used – but it was the toughest piece of equipment on that dive-boat. It had come through the test triumphantly. It is still working perfectly today.
As scottaw has said above, it was almost certainly the increased voltage and current that had led to the accelerated effect of electrolysis. With the stock low-power 4.5V bulb running on alkaline cells, this effect might only have been very slight, and possibly not noticeable at all. I rather wonder how these lights did actually perform with the British Royal Navy – did the Navy divers notice any problems with them after a while? Could that be why they were withdrawn from service and sold, with one of them ending up in my hands? It would be fascinating to know more.
Just one other thing to round off this tale: At the current rate of exchange, the 1p coin I used (UK £0.01) is almost exactly equivalent to 2 US cents.
So I can truthfully say - this story really is just my $0.02¢.
Thanks for reading it!
Stereodude
Flashlight Enthusiast
Re: Diving with "The Moderator" - Part III added!
Next week, on Days of our Flashlights, DM51 will tell the tale of his trip to Tunisia and how a brass washer and super glue saved the day.
Next week, on Days of our Flashlights, DM51 will tell the tale of his trip to Tunisia and how a brass washer and super glue saved the day.
DM51
Flashaholic
Re: Diving with "The Moderator" - Part IV added - my $0.02!
Lol, S-dude! And well spotted for noticing that the label showed I was offline.
Lol, S-dude! And well spotted for noticing that the label showed I was offline.
schiesz
Flashlight Enthusiast
Re: Diving with "The Moderator" - Part IV added - my $0.02!
I thought the red light was funny also. Mine is either green or not lit. Red is obviously reserved for mods that are out diving.
Great story, and such a cool light!
schiesz
I thought the red light was funny also. Mine is either green or not lit. Red is obviously reserved for mods that are out diving.
Great story, and such a cool light!
schiesz
theamazingrando
Newly Enlightened
- Joined
- Oct 31, 2005
- Messages
- 184
Re: Diving with "The Moderator" - Part IV added - my $0.02!
So, was the coin dissolved at all? I think 1p coins are actually mild steel these days, but if it's an older coin it would be bronze. In either case, it should not have served as a sacrificial anode (I think).
Maybe it worked by creating a better electrical path and changing the difference of potential between steel and aluminum parts.
I don't know. I'm intrigued.
So, was the coin dissolved at all? I think 1p coins are actually mild steel these days, but if it's an older coin it would be bronze. In either case, it should not have served as a sacrificial anode (I think).
Maybe it worked by creating a better electrical path and changing the difference of potential between steel and aluminum parts.
I don't know. I'm intrigued.
Illum
Flashaholic
Re: Diving with "The Moderator" - Part IV added - my $0.02!
something tells me the royal navy light you have is a clone of the real thing....and that when the light was made the seas had lower salinity...or the light was made to be a "fresh water" dive light:thinking:
something tells me the royal navy light you have is a clone of the real thing....and that when the light was made the seas had lower salinity...or the light was made to be a "fresh water" dive light:thinking:
Illum
Flashaholic
Re: Diving with "The Moderator" - Part IV added - my $0.02!
DM51, I think your experiment bears witness of empirical evidence professionally obtained to explain why most dive lights seem to be of polymer shells rather than metal...Although unbeknownst to the precipitating members here, DM51's experiment answered a few important questions in relations to underwater use of flashlights, a good read if you have the time IMO
Free :bump:
DM51, I think your experiment bears witness of empirical evidence professionally obtained to explain why most dive lights seem to be of polymer shells rather than metal...Although unbeknownst to the precipitating members here, DM51's experiment answered a few important questions in relations to underwater use of flashlights, a good read if you have the time IMO
Free :bump:
tebore
Flashlight Enthusiast
Re: Diving with "The Moderator" - Part IV added - my $0.02!
Just make sure your lights don't have exposed aluminum other mixed metals in there. Like a polish aluminum light with a SS bezel. You shouldn't have of a problem.
What is the current status of "The Moderator"? is it retired? Please fill us in DM51.
Just make sure your lights don't have exposed aluminum other mixed metals in there. Like a polish aluminum light with a SS bezel. You shouldn't have of a problem.
What is the current status of "The Moderator"? is it retired? Please fill us in DM51.
DM51
Flashaholic
Re: Diving with "The Moderator" - Part IV added - my $0.02!
The main lesson, as you say, is that mixing the wrong metals in one light is a bad idea.
It's still in working order, though I haven't dived with it since then. I've learned about galvanic corrosion (thanks to knowledgeable CPFers) and I need to do some more reading on that. The copper in the coin would probably prevent excessive damage of the sort I observed in the first few dives, but the zinc idea is something I need to read up on when I get time.
The main lesson, as you say, is that mixing the wrong metals in one light is a bad idea.
Packhorse
Flashlight Enthusiast
Re: Diving with "The Moderator" - Part IV added - my $0.02!
Yeah not mixing metals will help but also try and avoid using the body of the light in the electrical circuit.
My dive Mag lite has done 100+ salt water dives and the only corrosion showing was between the nickel plated cable gland and the tail cap. I have since rebuilt the light and now use a plastic cable gland.
Yeah not mixing metals will help but also try and avoid using the body of the light in the electrical circuit.
My dive Mag lite has done 100+ salt water dives and the only corrosion showing was between the nickel plated cable gland and the tail cap. I have since rebuilt the light and now use a plastic cable gland.
mikel81
Newly Enlightened
Whew, good read. :twothumbs
Ok this reminds me of a dive trip I went on with my dad years ago. When one of our dive lights died, we used 2 ziplocks and put a normal flashlight inside. When we hit a certain point the pressure would click the lights switch, and turn off. It was pretty funny until someone figured it out.:thinking:
Ok this reminds me of a dive trip I went on with my dad years ago. When one of our dive lights died, we used 2 ziplocks and put a normal flashlight inside. When we hit a certain point the pressure would click the lights switch, and turn off. It was pretty funny until someone figured it out.:thinking:
That was a very good story. I enjoyed it a lot.
Does the M in your name stand for MacGuyver?
Do you think it's possible that there could be one metal (copper) clip missing from the light you received?
Does the M in your name stand for MacGuyver?
Do you think it's possible that there could be one metal (copper) clip missing from the light you received?
Visible EM Wave
Enlightened
Thank you for sharing your story DM51.
From the modification to the investigation, it's a true flashaholic story.
I enjoy reading it a lot, too. Thanks.
From the modification to the investigation, it's a true flashaholic story.
I enjoy reading it a lot, too. Thanks.
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