[PSUBS-MAILIST] Foam preperation

Mon Jul 8 22:05:54 EDT 2019

I would say that was good test.  It established you can not use this foam.  You just have to push on and find a syntactic foam that will work.

Cliff

Sent from my iPhone

> On Jul 8, 2019, at 8:43 PM, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Bad news,  the test piece that I dropped down to 900'  , it didn't crush , but it absorbed water.  So it lost a lot of its buoyancy.   
> 
> 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: Fri, 28 Jun 2019 16:15:09 -0700
> 
> Alan,              I've done one small test piece so far and it did give off some heat.  I'm planning on doing a larger piece that I'm going to drop in the ocean, it will be interesting to see how that goes.  I'm more inclined to pour larger amounts for a couple of reasons, first I think you get a better and more accurate mix of the A and B, and also where I'm pouring into my cavities I don't want to inadvertently seal off areas that I will not be able to get to to complete the pour.  So I'd rather error on over pouring a bit so I have foam pushing out the vent holes.  
> 
> 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: Sat, 29 Jun 2019 09:18:40 +1200
> 
> All,
> as we are talking about testing this for General Psubs use I'll elaborate
> on something I mentioned earlier.
> In the product specifications below it mentions that in the setting of this product
> the temperature is critical, & that temperatures below 75 degrees F will make a
> denser product. One would assume that temperatures above 75 F would make
> a less dense & hence weaker product. 
> With 2 part chemical reactions there is generally a heat produced & this is 
> exponentially greater the thicker the pour. I used to use casting resins for art
> & they would get very hot on thick casts.
> If this were the case then filling any large voids in one pour may cause the
> centre of the material to be a lot weaker than the outside.
> To check this we could ask the rep about thick pours, do a thick pour & cut it
> in cross section to see if it is less dense in the middle or stick a heat probe in
> the middle of the pour to check for an increased temperature.
> All expansion rates and times given are temperature critical. Temperatures below 75 degrees F will lower the expansion rate therefore requiring more foam. Ideal working temperature is 75 to 80 degrees F or above.
> Accurate measuring of these products is extremely critical.
> Alan
> 
> All expansion rates and times given are temperature critical. Temperatures below 75 degrees F will lower the expansion rate therefore requiring more foam. Ideal working temperature is 75 to 80 degrees F or above.
> Accurate measuring of these products is extremely critical.
> On 28/06/2019, at 11:04 PM, Jon Wallace via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Not my forte, but given the hardness of this product when cured is there really an expectation that it is going to deform in a visually measurable way and spring back into shape from a depth test?  Seems like it's more likely to either structurally fail or not with obvious non-elastic results such as cracks, cavities, etc, hence the weight test to see if it absorbs water.  I'm thinking the dunk test from the sailboat is a good first start.
> 
> The cost of this product seems to be on par with trawler floats from a pound to pound buoyancy perspective but it has the advantage of allowing custom shaping.  I'm interested in the results.
> 
> Should we invest in a small amount of this product and put it to some more rigorous pressure testing?
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