Across International

[Gray Wolf]

"For electrical in vacuum chambers, I've usually just potted the wires in a pipe bushing with epoxy, but for this application we are concerned about the out gassing components, so are taking a different ploy."

"but for this application we are concerned about the out gassing components,"

Which "outgassing components" are being referenced? Bringing the wiring in through a nipple and sealing the gap with epoxy or silicone sealant would seam just fine to me. And if you needed more finesse, surely there must be commercial air tight through the wall connectors if one were willing to dig deep enough, what's Cascade TEK and now AI using?

Epoxy components. Check the MSDS and note that some say:

Chronic effects Contains material that can cause target organ damage.

Carcinogenicity Contains material which may cause cancer, based on animal data. Risk of cancer depends on duration and level of exposure.

That leads me to be cautious in introducing them into a pharmaceutical system without further research on specific resins.

Cascade TEK pots their own. I'll ask Catherine if they will share.

 

[SkyHighLer]

^ My thought is the epoxy once cured shouldn't be releasing anything of much significance.

In case of failure it would be beneficial to have each heater and sensor connected inside with it's own connector for easy replacement. Most standard panel connectors should be able to be sealed with a liberal glob of epoxy or silicone sealant on the entry side. Don't ask me to do the research, but both Mouser and Digi-key are great with small electronics orders.

 

[Gray Wolf]

^ My thought is the epoxy once cured shouldn't be releasing anything of much significance.

In case of failure it would be beneficial to have each heater and sensor connected inside with it's own connector for easy replacement. Most standard panel connectors should be able to be sealed with a liberal glob of epoxy or silicone sealant on the entry side. Don't ask me to do the research, but both Mouser and Digi-key are great with small electronics orders.

They still out gas enough that NASA has to have any of it going into space vacuum baked until it stops out gassing. Out gassing in space, is propulsion.

The threaded brass rod pass through has washers, nuts, and connectors on both ends.

 

[GratefulOne]

Epoxy components. Check the MSDS and note that some say:

Chronic effects Contains material that can cause target organ damage.

Carcinogenicity Contains material which may cause cancer, based on animal data. Risk of cancer depends on duration and level of exposure.

That leads me to be cautious in introducing them into a pharmaceutical system without further research on specific resins.

Cascade TEK pots their own. I'll ask Catherine if they will share.

There are about as many ways to formulate epoxies as there are stars in the sky. Most formulations do have a things you don't want to make it into your final product. There are food grade products made. Even these products need a full cure before being ready for food contact. With the proper formulation and proper cure there are epoxies safe for this use. It may not be practical for most people though if they have no access to small quantities.

 

[SkyHighLer]

Time for me to go get stoned, we're arguing whether at the most one or two square inches of exposed 'solid as a rock' epoxy is going to offgas under vacuum significant amounts of harmful chemicals...

peace

 

[GratefulOne]

Time for me to go get stoned, we're arguing whether at the most one or two square inches of exposed 'solid as a rock' epoxy is going to offgas under vacuum significant amounts of harmful chemicals...

peace

I'll join you!!!!

We are not arguing. We are helping each other to reach new knowledge! Thermoplastics were my old profession so it and fire marshal are about the only topics I really know anything about

Where did my bowl go?

 

[Gray Wolf]

There are about as many ways to formulate epoxies as there are stars in the sky. Most formulations do have a things you don't want to make it into your final product. There are food grade products made. Even these products need a full cure before being ready for food contact. With the proper formulation and proper cure there are epoxies safe for this use. It may not be practical for most people though if they have no access to small quantities.

Thanks GO! Do you have a food grade that you suggest?

 

[Gray Wolf]

Time for me to go get stoned, we're arguing whether at the most one or two square inches of exposed 'solid as a rock' epoxy is going to offgas under vacuum significant amounts of harmful chemicals...

peace

I thought we were still at the discussing point, at worst in preparation for a debate, so I must already be stoned to miss the arguing part.

Good idea on joining those of us with an earlier start!

What is the permissible exposure limit to something identified as a carcinogen, mutagen, or teratogen?

Cancer is the bete noir of my family, taking more than all other causes together, so my personal policy is to not use them if there are alternatives without the same baggage.

One alternative is to use what you please and out gas it by vacuum baking before using.

Depending on what it is, it might also be a good thang to scrub out the oven afterwards and before using for pharma or medibles.

 

[montroller]

They make vacuum epoxy that is designed to not outgas...

Loctite for example should be able to be used

http://www.idealvac.com/files/brochures/Loctite1CHysol_TechSheet.pdf

Outgassing Properties:
Total Mass Loss, % 0.81
Collected Volatile Condensable Material, % 0.02

That is an extremely negligible amount especially if you use it sparingly.

Also Torr seal claims they have no outgassing up to 10-9 torr... which we would never come close to reaching in our application.

http://www.idealvac.com/files/brochures/Torr_Seal2.pdf

 

[GratefulOne]

Thanks GO! Do you have a food grade that you suggest?

Nothing off the top of my head. Coatings and structural resins were the area I dealt with mostly. Since potting is not a structural issue you really only need a resin that likes to form complete long chains quickly (epoxies are most likely the best choice in this case). I have seen many resins that would likely work.

This is promising link that came up when I googled food grade epoxy: http://www.masterbond.com/properties/food-safe-adhesives-sealants-coatings-encapsulation-compounds

It looks like more companies are offering thermoset resins in small quantities. 15 years ago it was really hard to find. The one caution I would put out there is to make sure of the production date of the resin. If the company does not have a ton of volume it might take too long to rotate stock.

One other subject this epoxy is food grade and designed to coat the inside of tanks. It is highly chemical resistant. This is the first one I have looked at but shows there are good resins for coating the insides of the butane tanks to prevent rust.
http://www.resoltech.com/IMG/pdf/DS_-_4070AL.pdf

 

[montroller]

Looks like NASA did a pretty extensive study on outgassing you can check out there results here

http://outgassing.nasa.gov/index.cgi

The search function is pretty terrible so just click on low outgassing then select adhesives and click "execute section C"

 

[Gray Wolf]

Nothing off the top of my head. Coatings and structural resins were the area I dealt with mostly. Since potting is not a structural issue you really only need a resin that likes to form complete long chains quickly (epoxies are most likely the best choice in this case). I have seen many resins that would likely work.

This is promising link that came up when I googled food grade epoxy: http://www.masterbond.com/properties/food-safe-adhesives-sealants-coatings-encapsulation-compounds

It looks like more companies are offering thermoset resins in small quantities. 15 years ago it was really hard to find. The one caution I would put out there is to make sure of the production date of the resin. If the company does not have a ton of volume it might take too long to rotate stock.

One other subject this epoxy is food grade and designed to coat the inside of tanks. It is highly chemical resistant. This is the first one I have looked at but shows there are good resins for coating the insides of the butane tanks to prevent rust.
http://www.resoltech.com/IMG/pdf/DS_-_4070AL.pdf

Thanks, I'll check them out!

We successfully used three part epoxy to coat 316SS nitric/HF chemical cleaning tanks, but this application is to cast a thick plug, with conductors running through it, so rigidity and structural strength are required, in addition to chemical resistance and components that don't raise your eyebrows in food/pharma applications.

 

[KONY]

Sorry if this has been mentioned already, couldn't find it;

Do ambient room temps much affect the usage of the 1.9 across ovens? Got a slab of marble in there that it sits on, so I want to say no or very minimal but not really sure if it would be better to have the oven in a heated room this time of year. It was about 10 degrees F out last night and Id guess 30 ambient in the room the oven is in (unheated garage.)

 

[GratefulOne]

Thanks, I'll check them out!

We successfully used three part epoxy to coat 316SS nitric/HF chemical cleaning tanks, but this application is to cast a thick plug, with conductors running through it, so rigidity and structural strength are required, in addition to chemical resistance and components that don't raise your eyebrows in food/pharma applications.

When I say structural strength is not needed I was comparing it to laminates where real strength is required. For a potting compound the only strength needed is: hold everything still, prevent leaks and not break over time. Nearly any resin will have enough strength to do that. My point was to note that the strength of the resin can be dropped out of the equation.

You would need to make sure the resin can handle cast style pours. Some very active resins will generate too much heat and crack if poured thicker than they are designed.

 

[Powder2Burn]

New question

but how long do you keep the vacuum pump running on the oven? do you just pull the vacuum down to 29hg and close the vacuum valve to hold it? OR do you let the pump run all the time pulling the vacuum as the oven heats over night?

sorry for a dumb question

 

[SkyHighLer]

New question

but how long do you keep the vacuum pump running on the oven? do you just pull the vacuum down to 29hg and close the vacuum valve to hold it? OR do you let the pump run all the time pulling the vacuum as the oven heats over night?

sorry for a dumb question

You can do either if your setup holds vac well, up to you, but think about this, do you know how much deeper a vac you're pulling after the dial gauge stops moving? I keep plugging getting an electronic micron meter like my Yellow Jacket 69075 and learning first hand what's actually going on for yourself. Here's a quick eye opener, place a never been opened one gallon ziplock style bag in your chamber and take it down without heat while watching the dial gauge. The bag should fully open, almost taunt, but it may take several minutes after your dial gauge maxes out. If it doesn't even partially open you've got a leak that should be checked out.

 

[Powder2Burn]

we did try both way with pump on and pump off.. with the pump on we pull until we got a big mushroom bubble the dropped the vac to zero and did it again.. 3 times .. then let set in oven with pump on for 8 hours.. we have really know ID what we are doing or what we are looking for. our oven is .9 cf running at 110 deg with a clay shelf / rack. seams to be working.. but it seams to me if we leave the pump on we will get a deeper vacuum is that correct?

 

[SkyHighLer]

Go to your local supermarket and buy a box of their cheapest generic one gallon ziplock bags, place one without ever opening it in your chamber and take the vacuum down without turning the heat on, don't turn the pump off, watch.

Here's pictures of a quart bag and a gallon bag expanded under vacuum.
https://www.icmag.com/ic/showpost.php?p=6647368&postcount=2

 

[NorPene Solutions]

AI, 1.9 or AI 3.2, which is better

AI, 1.9 or AI 3.2, which is better

I am having a hard time deciding between buying two of AI's, 1.9 ovens using stone shelves or one of their 3.2 ovens with individual temp controlled alum shelves. They each have their own options. The newer 1.9's seems to be designed for our purpose but i like the thought of individual temp control so as to be able to work with different products and their individual temp requirements at the same time. How many of you are using the inert gas inlet port system? Does it make that much difference to the end product? Any thoughts between the 2 different ovens would be greatly appreciated.

AI just cranked up the price on the 1.9 another hundred bucks because of all the demand for the product from our industry as of the first of the year. They only raised the price of the highly sot after 1.9's not the 3.2 or bigger. Sure seems like a cash grab.

 

[Dab Strudel]

Think of how much product you take out each time you open your collection tank. Will it cover 224 sq in better or 324 sq in? Figure how thin you like it, I prefer .6 to .75 g per sq in to get a nice purge, some may be ok with more. By my numbers, at most your putting 168g on the 1.9 stones or 243g on the 3.2 aluminum shelves. 700g~ purging at any given time with the 3.2. Even if you use half the shelf at a time I prefer and will be buying the 3.2 for the (3) individually heated shelves. With the shelves ability to block heat between shelves id be ok spending 5k on properly heated shelves with being able to know how hot they are at all times. The fun part will be to see how much the heat from all the shelves effect each other. Anyone who has one, can you speak on that?