Thinktank Revision 2.0

[3.0charlie]

Ok. I'm writing this while still at work. Some (bad) news:

1- I just can't find a freakin' Report in this Company. My Engineer remembers seeing a M&P Report about RTV157 being tested down to -95C, with success. Now, were is that Report? He's looking for it. But since RTV157 is dirt cheap (you can buy it at Canadian Tire - same stuff), I would recommend to test it using that dead-cold iso for a few cycles. Just make sure it's fully cured. And since that iso will be dead-cold, see point 2...

2- I (again) explained what you wanted to do. His question: the board will be located in an enclosure filled with that iso, right? And that PCB is made of multi-layered fiberglass, if I'm not mistaken. The fiberglass can handle the cold and the iso no problem he says, but the resin resistance to cold and iso is another story... with time, the resin will degrade to the point of cracking the fiberglass. He said that since a test of that RTV is needed to confirm its resistance down to -95C, why not test a PCB at the same time?

3- Iso should not be a problem for that RTV.

[Jack Rabbit]

Originally Posted by 3.0charlie

statement of the week: "He's freakin' nuts!"

I think it is more of a weekly statement.

[BrainEater]

Heheheh.........yea weekly statement...heh

Originally Posted by 3.0charlie

Ok. I'm writing this while still at work. Some (bad) news:

1- I just can't find a freakin' Report in this Company. My Engineer remembers seeing a M&P Report about RTV157 being tested down to -95C, with success. Now, were is that Report? He's looking for it. But since RTV157 is dirt cheap (you can buy it at Canadian Tire - same stuff)..

Ok , 'the stuff you buy at Canadian Tire' that you speak of , I assume , is GE Silicone II ?

Interesting.That's what the original tank is made from.I know for a fact it's Iso resistant.

I've actually found rtv157 locally ,but if I can confirm they are in fact the same thing ,thats good to know.I'll get some glass strips on order and do some tests.I've got silicone II in the workshop.

--------

As far as # 2 goes , Motherboards or any other PCB are generally not affected by IPA.It's one of the approved solvents for cleaning them.

I have aready done some minor tests....perhaps you remember this. hehe

Thanks again John ! , I'm quite curious about the whole silicone thing.



edit : I just checked the prices.They can't be the same thing , RTV157 is ten times the cost of GE silicone II , @ 33$ per 82 ml tube.Not that I'm complaining , thats still totally reasonable.

[Cowinacape]

You sir are a sick sick man, great work Looking forward to more updates!

[3.0charlie]

Originally Posted by BrainEater

Heheheh.........yea weekly statement...heh




Ok , 'the stuff you buy at Canadian Tire' that you speak of , I assume , is GE Silicone II ?

Interesting.That's what the original tank is made from.I know for a fact it's Iso resistant.

I've actually found rtv157 locally ,but if I can confirm they are in fact the same thing ,thats good to know.I'll get some glass strips on order and do some tests.I've got silicone II in the workshop.

--------

As far as # 2 goes , Motherboards or any other PCB are generally not affected by IPA.It's one of the approved solvents for cleaning them.

I have aready done some minor tests....perhaps you remember this. hehe

Thanks again John ! , I'm quite curious about the whole silicone thing.



edit : I just checked the prices.They can't be the same thing , RTV157 is ten times the cost of GE silicone II , @ 33$ per 82 ml tube.Not that I'm complaining , thats still totally reasonable.

Hehe... Welcome in the Aeronautical World Ross! 33$ a pop is nothing, really...! Remember that any product used on an aircraft has to meet stringent rules, test samples have to be made over and over multiple samples batches, Certificate of Compliance Reports have to be made for all batches. That adds to the cost of everything we use.

Believe it or not but GE Silicone II is of the same family as RTV157. It meets the specs of ASTM C-920, which in turn is the manufacturing regulatory equivalent of Mil-A-46106, the specification on which RTV 157 is based. If you find one spec or the other (or any silicone that is part of the RTV100 series or the Dow Corning 73x series), they are the same with minor differences.

Check out your link (GE Sealants and Adhesives - Residential GE Silicone II* Window and Door) and the specs shown at the buttom; now compare this to the RTV100 spec page: GESilicones - Master Grade.

Paste adhesive with FDA, USDA, NSF, MIL-A-46106 (Group I, Type I), MIL-S-47162, MIL-S-14112 and UL recognition.

If you scroll at the bottom, you will find the Regulatory Compliance table and the Federal Specifications; ASTM C-920 is amongst them.

Now, for #2... you did perform that test, but that was with under ambiant temps, right? I wrote:

The fiberglass can handle the cold and the iso no problem he says, but the resin resistance to cold and iso is another story... with time, the resin will degrade to the point of cracking the fiberglass.

Have you tested this?

If you want some RTV157, I can find samples at work and send them over.
John

[BrainEater]

The computer I dunked in iso and dry ice still works fine...now it was only super cold for a couple hours ,but as far as long term degradation of the PCB's , well thats something we'll test later , once this worklog is complete .

------

That's interesting about the silicone...I guess I need to setup some tests.I'm actually totally curious how silicone II will tolerate the cold.I'll pickup some glass tomorrow and set up a test.

I won't turn down free silicone.If you can find some samples I'd love em.
Thanks !!

[S_G]

I don't turn down free silicone either.

[BrainEater]

Major update time.
---------------------

I have found my pump.

A big Thank you very much to Horatio at Chinook Pumps Ltd of Calgary.

The pump I'll be ordering on monday is the FRX 75-SP from MP pumps. PDF here.

It's an all 316 Stainless steel , self priming , centifugal pump , with an explosionproof motor.Cost ~ $400

------------

So that's it.
Research complete.I am confident I have , (or will get) every major component I need.There are no more giant hurdles.

------------

All I have to do now , is build it.

[matsta31]

good news, cant wait for the build !

[3.0charlie]

That's the best news. Let the fun begin.

I'll find some RTV samples on Monday.