Bell/Alarm for low air

[Bronze06]

Thanks for the information Herman. I'll keep you posted.

[joeym35a2]

I have a nemrod tank that makes a kinda bell type sound when low on air . Not sure how but it does it about 4 minutes before I have to flip j valve I'll see if I can post vid when I get off work

[antique diver]

I don't know if Nemrod had a valve that intentionally made noise below a certain pressure, but I have had a number of J-valves that sang to me at low pressures before opening the reserve. I assume it may have something to do with the spring vibrating as the air passes through a partially closed reserve seat.

[joeym35a2]

I don't know if Nemrod had a valve that intentionally made noise below a certain pressure, but I have had a number of J-valves that sang to me at low pressures before opening the reserve. I assume it may have something to do with the spring vibrating as the air passes through a partially closed reserve seat.

Thank you I always wondered about that but never got around to posting the question

[luis]

I assume it may have something to do with the spring vibrating as the air passes through a partially closed reserve seat.

That is correct. It is just what happens when forces are so close to equilibrium, between a spring and the pneumatic forces. You are getting natural vibrations with the spring (and probably some vortex shedding around the seat). I am fairly sure (based on several technical reasons and lack of consistency) that it was not intentionally designed to cause noise, but it is a natural side effect of the mechanism.

[joeym35a2]

I will have to take your word on the vortex thing as that flew way over my head

I do think it's accidental and not designed to do that bit it does so consistently and there is definitely a bell ring to it . So much so that I pulled the valve to try and figure out how it was doing it

I have tried for an hour straight to upload it but gave up trying in the video it is loud enough to be heard on camera over all the bubbles of multiple divers in the same area so although it wasn't designed to do it it does it and it's pretty cool that it does I wish all my j valves where so loud

Thanks again for solving that mystery for me

[captain]

The early USD and Voit J valves used a hard metal ball seat in the reserve rather than the later softer nylon seat. That may have contributed to the ringing sound.

[luis]

I do think it's accidental and not designed to do that bit it does so consistently and there is definitely a bell ring to it .

I was referring to lack of consistency from one valve to the next (of the same design). Not from one day to the next, with the same valve.

[joeym35a2]

I knew what you meant I have talked to one other person with the same valve before and they just looked at me funny when I brought up ringing

[joeym35a2]

ok somone better tell me i have a super duper rare tank and valve and that noise is not something that involves vortexs or shredding. i just spent 4 hours trying to upload this stupid video of a video becuse i have no cd rom on computer i have no wifi wich i guess you tube mobile requires wifi but i steal wifi by jailbreaking and turning my phone into a mobile hot spot only to find out i dont remmber my password to youtube and of course trying to figure out how to transfer video of video to computer from phone

well anyhow is this what "singing" sounds like?

i have 10 tanks most with j valves and have never heard any differnce even from the old us divers half inch ones or the voit ones

please tell me i didnt waste my money buying this stupid nemrod tank and plate for 10 bucks

and what ever happened to just putting in a floppy disk in computer and typing load"*",8,1 and having it do what you want it to do?

sorry for the crappy recording it sounds better and more bell like on the dvd

http://youtu.be/U1iI6HP5kRw

[joeym35a2]

Any one? I really don't know what singing would sound like I've never heard it with any tanks I own is this considered singing?

[captain]

If you are referring to the sound heard during inhalation, I am very familiar with it. Usually it occurs only with the J in the up position. It doesn't matter what the tank pressure is, it is caused by the air forcing open the reserve on each inhalation. With the reserve down it should not sound the same. Seems some types of J's do it more than others. The old USD's and Voits J60 with the top wing nut handwheel seem to do it more than the later side handwheel valves.

[Bryan]

I have several that act like Tom describes.

Sent from my SGH-T989 using Tapatalk

[joeym35a2]

Ok thanks I remembered being 12 and instructors telling me I would hear a difference between being on reserve and not if I was using a j valve and in 20 something years never heard it

I dove yesterday with that tank paying more attention and it was only on inhale and with reserve off at lower tank pressures it was very faint at high pressure and now after googling vortex shedding and the last 2 comments I now understand the how and why

[Robohips77]

I actually still have the US Divers valve. Has not been used in 30 years but still in good condition. Let me know if you need more pictures.