Where Can I Buy Burst Disks?

[JS1scuba]

Actually, my trimix instructor is doubling up the burst disks in our valves for us. I'm just following orders (which I'm happy to do):

"Rick! Get a dozen burst disks."

"Sir, yes sir!"

I'll ask him about the bolt.

Rick -- you seem to be a reasonable guy but your Trimix Instructor is committing a crime and putting more people at risk for NO reason. Double disking a cylinder is a gross violation of DOT laws PERIOD.

Who is this moron who is doing this ?

Do you know why this is dangerous ?

shaking head ..........

 

[Rick Inman]

Rick -- you seem to be a reasonable guy but your Trimix Instructor is committing a crime and putting more people at risk for NO reason. Double disking a cylinder is a gross violation of DOT laws PERIOD.

Who is this moron who is doing this ?

Do you know why this is dangerous ?

shaking head ..........

Ok... I am not 100% sure if this is his plan... I may have misunderstood. I will clarify.

 

[426Scuba]

Rick DON'T DOUBLE THEM UP! or at least admit to doing so. If the cylinders are properly filled there is no need and as pointed out breaking the law and very dangerous. I worked for a compressed gas valve manufacturer (not scuba), and I will say a few things, Burst discs are regulated under CFR 49 chapter 100. They are rated by type and pressure rating of the cylinder used on. I dont have the numbers infront of me so I will not quote them, but if I remember correctly they are usually rated from 4 to 5 thirds of the rated pressure (almost all hydro's are performed at 5/3 of rated pressure). Don't try and make one yourself there is a lot of testing in material to produce the proper failure point. The material we had made was made to within +or- .0001. Also DO NOT reuse once removed! Spend the money and do it correctly this is not an area to DIY or be cheap.

 

[captain]

I see only two instances where a burst disc will prove to be needed, one would be the case where the tank is filled by accident or intentionally beyond its hydro test pressure or the tank is involved in a fire. CFR 49 only applies to tanks in commercial use such as tank rented or sold by a business, tanks filled by a commercial business or transported for commercial reasons. Privately owned transported and filled tank do not fall under the regulations of CFR 49.

 

[pescador775]

Captain, that sounds right. I don't know where these "laws" come from as they apply to private ownership and transport. I guess this will be with us forever, the urban legends and myths. Correct me if wrong, but I hear that the Europeans don't use burst discs on their valves.

I hear that cave divers double up discs for their own reasons. Personally, I'm not particularly concerned about discs except when it is the wrong disc. Many years ago, I bought a tank with valve from a company in Chicago (Berry Dist). The steel tank was rated for 3000+. I used the tank for 10 years. One day, while the tank was in the back of my Suburban, it let go, whoosh!. On examination, there was a "gotcha" moment; the burst disc was rated 2250 psi WP! Yeesh.

 

[do it easy]

Just out of curiousity, did you have the same burst disk in there for 10 years, or was it replaced with the wrong "size" at some point during those 10 years? 3000+ psi would be near the hydro test pressure for that burst disk!

 

[COVCI]

I don't know where these "laws" come from as they apply to private ownership and transport.

"When transported by motor vehicle in conformance with this section, a material of trade is not subject to any other requirements of this subchapter besides those set forth or referenced in this section.

(a) Materials and amounts. A material of trade is limited to the following:

(2) A Division 2.1 or 2.2 material in a cylinder with a gross weight not over 100 kg (220 pounds), or a permanently mounted tank manufactured to the ASME Code of not more than 70 gallon water capacity for a non-liquefied Division 2.2 material with no subsidiary hazard."

Call your regional US DOT Hazmat Enforcement Office if you need additional clarification.

Hope this helps.

Chris
COVCI

 

[wedivebc]

Ok... I am not 100% sure if this is his plan... I may have misunderstood. I will clarify.

I assume you are following a DIR course of training. Here is a case where DIR takes stuff they learn in WKPP and try to apply it to inappropriate activities. Yeah we all know they cave fill for those long pushes in the cave and for the most part people turn a blind eye to it. Then the GUE instructors take that and make it SOP for all DIR divers for any environment and that is where I have trouble getting my head around the whole DIR thing. We are not using common sense here and you are blindly following the leader down that path. Frankly I am surprised at you Rick.

 

[Rick Inman]

We are not using common sense here and you are blindly following the leader down that path. Frankly I am surprised at you Rick.

It's not a GUE class and I'm not blindly following anyone. As you can see, I'm asking questions and learning, and I've been discussing this all with my instructor.

Thanks for caring.

 

[wedivebc]

It's not a GUE class and I'm not blindly following anyone. As you can see, I'm asking questions and learning, and I've been discussing this all with my instructor.

Thanks for caring.

I am a little touchy about this matter right now. There was a thread about a new dive charter on the Island. I think yipee! Upon reading his web page it appears you either dive DIR or don't dive with him. He even posted a list of required eqipment including doubled burst disk. I pointed out to him that it is probably illegal to do that In Canada. His reply was screw transport Canada. Others were less tolerant of his insistence on DIR or don't dive attitude and he pulled his posts.
Although it is very unlikely anyone would check if you were to be bringing doubled disc tanks into Canada you would be breaking the law. I don't know about home use but a charter operator is definately under TC juristiction. Since double discing is of little benefit if your LDS will only pump to 3600psi or so, there is not much point. Should you go to Florida you will probably rent there anyway and if you bring tanks you will have to remove valves to fly. You could double disc then. I think DD is maybe only slightly risky but the risk is to others besides the diver and do you have the right to endanger my life?