[PSUBS-MAILIST] Foam preperation
Alan via Personal_Submersibles
personal_submersibles at psubs.org
Fri Jun 28 01:34:31 EDT 2019
Brian,
That's a different product than what you are using isn't it?
Also they are using prefabricated sheets formed in controlled conditions
that they machined, rather than a 2 part pour method that you are using.
Can you check with your products technical adviser on whether you would
loose strength on a thick pour due to the higher internal temperatures due to
chemical reactions?
Generally with plastic items there is a 4 X safety factor required where human
life is at risk. This wouldn't apply with a ROV.
You might be on to a good thing, but just being anal about safety as usual.
Someone kindly pointed out that Alan was an anagram for anal lol.
Cheers.
> On 28/06/2019, at 4:18 PM, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
> https://www.generalplastics.com/case-applications/subsea-foam-equipped-rovs-dive-deeper
>
>
>
>
> --- personal_submersibles at psubs.org wrote:
>
> From: Cliff Redus via Personal_Submersibles <personal_submersibles at psubs.org>
> To: Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] Foam preperation
> Date: Fri, 28 Jun 2019 03:16:58 +0000 (UTC)
>
> This could work. Would need the pressure gauge to confirm that water did not leak out on return to the surface. It is probably easier just to cast a sample and send it to Hank to video at depth with a ruler behind it.
>
> To get a 16 lbf/ft^3 specific volume at one atm, the foam would have to have over 70% air trapped in the foam at the surface. I just can't see how this air in not going to collapse at depth to some degree.
>
> What you need is syntactic foam which was designed for this application. If the foam shrinks during the descent, you are going to have to use your MBT to compensate.
>
> I think you would do better to make a simplified syntactic foam with off the shelf polyester resin plus 3M glass micro-spheres as a filler. Without macorospheres, I think the best specific weight you can expect is 30-40 lbf/ft^3 but at lease you would be assured that this buoyancy was depth independent because the air filled glass microspheres would be keeping the from collapsing.
>
> Best Regards
>
> Cliff
>
>
>
>
> On Thursday, June 27, 2019, 09:32:28 PM CDT, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Maybe I could pour the foam into a large diameter pipe of say 5" x 10" long, close the pipe up with a bell fitting , plumb in a high pressure check valve, but before that put in a tee with a ball valve. As the pipe descends water comes in through the check valve as the foam ( allegedly) shrinks in volume. Then, when it is brought up the check valve keeps the pressure at the max depth pressure (600' depth) . When the pipe is at the surface it would still have the pressure of say 300psi. Then you could open the ball valve into a container and measure the amount of seawater that was drawn in . Maybe put a pressure gauge on there too.
>
> Brian
>
>
>
> --- personal_submersibles at psubs.org wrote:
>
> From: Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org>
> To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] Foam preperation
> Date: Thu, 27 Jun 2019 18:23:42 -0700
>
> Cliff, There is probably a way I can determine if it shrinks or not at depth. I'm sure some clever person on this list could devise such a way .
>
> Brian
>
>
>
> --- personal_submersibles at psubs.org wrote:
>
> From: Cliff Redus via Personal_Submersibles <personal_submersibles at psubs.org>
> To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] Foam preperation
> Date: Thu, 27 Jun 2019 18:17:45 -0500
>
> Brian this would only be a good test if you had a camera on it with a ruler. I believe it would compress significantly then expand when you took back to surface. Without microspheres and or macro spheres, there is just nothing to keep the entrained air from shrinking . The pressure rating you need is what pressure you can take without any change in volume.
>
>
>
> Cliff
>
> Sent from my iPhone
>
> On Jun 27, 2019, at 5:01 PM, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
> I think what I might just do is just go out in my sailboat , off Pt. Magu, and drop a test plug down to 600' , bring it back up and check it out. Need to go out for a sail anyway !
>
> Brian
>
>
>
> --- personal_submersibles at psubs.org wrote:
>
> From: Alan via Personal_Submersibles <personal_submersibles at psubs.org>
> To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] Foam preperation
> Date: Fri, 28 Jun 2019 08:41:55 +1200
>
> Brian,
> If I had $3million spare I wouldn't spend it on syntactic foam.
> The danger is that if you were descending you might not know that you
> were becoming negatively buoyant until you tried to stop. Then when
> you tried to counter by filling the ballast tanks with air; because of the compression
> of the air at depth this might be a slow process.
> Bottom line is not to dive the sub in depths that are beyond your maximum
> dive depth till you are confident the foam isn't compressing.
> Alan
>
>
>
> On 28/06/2019, at 7:41 AM, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
> Alan, I don't have 3 million dollars. In any event I only need it to go to 300 psi, theoretically , I also have about 1000 cu ft of air on board and could easily fill my ballast many times over even if the foam were to shrink. I don't think the foam has an elastic property to it.
>
>
> Brian
>
>
>
> --- personal_submersibles at psubs.org wrote:
>
> From: Alan via Personal_Submersibles <personal_submersibles at psubs.org>
> To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] Foam preperation
> Date: Fri, 28 Jun 2019 07:33:33 +1200
>
> Brian,
> as Cliff says it may have a volumetric change under pressure that leaves
> you negatively buoyant. I am not sure how you would test this in a
> pressure chamber.
> As an example, a soccer ball could take a lot of pressure & look perfectly
> fine after a pressure test even though it might have been reduced to a
> fraction of its original size in the process.
> I was told that Alvin's syntactic foam & testing process cost $3 million.
> They put it together in segments after testing each individual segment.
> It might be perfectly OK though...
> Alan
>
> On 28/06/2019, at 7:03 AM, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
> I have a pressure gauge guy who does oil industry work that I think has a small chamber where I could test a plug of foam.
>
> Brian
>
>
>
> --- personal_submersibles at psubs.org wrote:
>
> From: Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org>
> To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] Foam preperation
> Date: Thu, 27 Jun 2019 11:37:26 -0700
>
> Cliff,
> It's rated for 580 psi.
>
> Brian
>
> --- personal_submersibles at psubs.org wrote:
>
> From: Cliff Redus via Personal_Submersibles <personal_submersibles at psubs.org>
> To: Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] Foam preperation
> Date: Thu, 27 Jun 2019 15:55:01 +0000 (UTC)
>
> Brian, this is not syntactic foam. It's made for marine service but not for deep submergence. It is really for surface buoyancy. I would not use this if you are relying on it for buoyancy at depth. It is the macro-spheres and microspheres in syntactic foam that prevent it compression at depth. I don't think this foam has either.
>
> Best Regards
>
> Cliff
>
>
> On Thursday, June 27, 2019, 10:45:29 AM CDT, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Clifff, Here is the foam, it's the most dense foam , the 16lbs / cu ft
>
> http://www.uscomposites.com/foam.html
>
>
> suppose to be good to 580 psi
>
> Brian
>
>
>
> --- personal_submersibles at psubs.org wrote:
>
> From: Cliff Redus via Personal_Submersibles <personal_submersibles at psubs.org>
> To: Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] Foam preperation
> Date: Thu, 27 Jun 2019 14:29:12 +0000 (UTC)
>
> Brian, I have been tied up and have not had a chance to follow this thread but I wanted to make sure you understand that unless this pour-able 2 part foam has a filler like 3-M's glass micro-spheres or some kind of incompressible macrosphere, then while the foam may appear rigid, it would compress when subjected to deep water and thus your buoyancy would be reduced. I don't think this is a replacement for syntactic foam if that is what you are doing. Can you send a link to the foam you are using?
>
> Best Regards
>
> On Wednesday, June 26, 2019, 10:30:48 PM CDT, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Hi everybody,
> I poured a small test piece of that 16 lb foam, man that stuff gets as hard as a rock ! very dense , and very light. This pouring of the foam is not going to be as straight forward as I thought, The barrier to contain the foam is working out good, I'm just using wood and thin 1/8" luan , then I'm covering that with 4 mil flexible plastic ( heavy garbage type bag) so the foam won't stick to it. But I'm worried that any little gaps I have and the liquid foam might run out the bottom of those areas before it starts foaming, so I'm cramming big blankets ( cheap moving blankets from harbor freight) in tight to contain any foam. That way I can get the cavity that I'm trying to fill completely maxed out. Waiting for an 80 + degree day .
>
> Brian
>
>
>
> --- personal_submersibles at psubs.org wrote:
>
> From: Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org>
> To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] Foam preperation
> Date: Mon, 24 Jun 2019 16:12:46 -0700
>
> My first batch of foam cam today ! yay ! two five gallon pails, A and B, should be interesting !
>
> Brian
>
>
>
> --- personal_submersibles at psubs.org wrote:
>
> From: hank pronk via Personal_Submersibles <personal_submersibles at psubs.org>
> To: Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] Foam preperation
> Date: Fri, 21 Jun 2019 17:47:56 +0000 (UTC)
>
> Brian,
> Did you find foam to fill the void?
> Hank
>
> On Thursday, June 20, 2019, 8:30:55 PM MDT, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Kind of unnerving drilling holes in my boat !
>
>
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