Any good tips on small indicator lamps?

Eskil

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Hi, for my canister, I'm considering a piezo pushbutton. But in that case, I'll need a small indicator light on the canister (for suit heating).
Advice on what indicator lights/3/5mm LED holders that are suitable for high pressure is very welcome!
Best regards, Eskil
 

DIWdiver

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Actually, I have used a larger version of that part. I think it fits a 12mm (maybe bigger) hole.

I had very little confidence that the o-ring would seal given the minimal pressure that can be applied with a nut with such steep threads, so I ended up changing out the o-rings for softer silicone ones. That seems to keep the rain out, but I've never put one under water.

The lens is pretty thin, and I'd be worried that it wouldn't hold up under the rigors of being on a piece of diving equipment.

I think you'd be much better off with a small diameter light pipe than a big lens like that.
 

Eskil

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Hi DIWdiver, thanks for your reply, and you many other good replies here!
I'm considering then to skip the switch on the cannister, and put it in the cable inlet under my inflation valve.

Then I stand back with two important questions:

1) Cable gland. The selection of 10bar approved glands with long metric thread, suitable for 9.6mm cable isn't large.
I bought these:
Lapp skintop MS-M-XL
https://se.lappgroup.com/fileadmin/documents/technische_doku/datenblaetter/skintop/DB53112005EN.pdf
but after getting it I notice the odd fingered plastic/rubber insert, it is not a rubber cone. The waterproofing between plastic and brass is that the plastic is pressed into a brass cone. Does that really work??

2) over pressure valve. My cannister will be hermetically sealed, and considering an over pressure valve, which could be a regulator (1st stage) over pressure valve. Do I need one, and do you have better suggestions?
 

DIWdiver

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Without seeing the actual gland parts, I can't really comment on it, but I have seen glands that have a rubber seal and a plastic part that helps the metal nut slide against the rubber as you tighten it.

I don't think LiIon cells offgas under normal operations as some other cells can, but you should make sure the canister cannot become a bomb if the cells fail catastrophically. UL requires a vent of 20 sq mm area (not 20 mm sq). I don't think a scuba OPV would meet this requirement.
 

Eskil

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IMG_3619s.jpg
IMG_3619s.jpg

Hi DIWdiver

Pictures below. Thanks for your time!

I guess the central reason for the plastic is to allow a large span of cable diameters.
https://www.dropbox.com/s/wdwql0rnjcp1wdk/IMG_3619s.jpg?dl=0
https://www.dropbox.com/s/w8o4uvtszg6g6w8/IMG_3621s.jpg?dl=0

Best regards, Eskil
 

DIWdiver

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As I suspected, the plastic piece is there to compress the rubber without chafing it. For smaller cables, you'd change the rubber part, not the plastic. Looks like that one is for the largest size that gland can take.

Nice pics, by the way.

If you want the pics to show up in the post, you have to edit the first part of the URL to https://dl.dropboxusercontent.com when you paste it in the 'insert image' box. And make sure they are no bigger than 800x800 pixels.
 

Eskil

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Thanks DIWdiver!
That insert is good all the way from 4 to 10mm cable, no wonder they prefer to stock one part instead of several.
My worry is that the connection between plastic and brass cone has to be watertight. I wonder if I should give the brass cone silicone grease, where it should tighten to the plastic?
Or buy new glands, like blueglobe
bg816ms
. Just annoying to have to pay 50USD again for minimum purchase + shipping.
Thanks for the tip on inserting pictures!
Best regards, Eskil
 

DIWdiver

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I doubt very much they are depending on a plastic to metal seal. The ones I've seen have a flange on the rubber that seals against the metal part.
 

lucca brassi

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Last edited:

Eskil

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Hi Lucca
Thanks for your help!
I also considered the polycarbonate screws. Never found out what the right glue was for bonding to PVC, so I ended skipping it in this build. Maybe in next build with a power regulator in the canister.
Thanks for you help guys, will describe my build in a separate thread now.
 

lucca brassi

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You don't need to bond.

The purpose of the sealant is to expand itself during polymerization and fill the slots in the screw helix , so it prevent of water invasion . ( you could use PTF teflon )
 

Eskil

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Thanks! Very interesting - I haven't tried sealants in critical applications. I guess I should find one with high unscrewing force - the locktite I bought for my espresso machine plumbing is ment for moderately easy disassembly. Do you recommend one?
 
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