Recent content by spiri

We have a small (15 X 25mm), thin membrane (0.03mm thick) that we currently inspect for pinholes and small cracks manually by backlighting and inspecting under magnification, one at a time. Does anyone know of an instrument that can do this inspection for us, with a high degree of accuracy?

Does anyone have any experience with creating a hermetic seal on metal housings that are sandwiching a thin metal membrane? Specifically with the fluid leak path between the metal and the plastic.

Hello, I'm having a hard time stamping and annealing grade 2 Ti foils (0.0125mm thickness). The ductility appears to decrease significantly after I vacuum anneal the Ti foil after stamping. I'm running them at a vacuum of 10-6, 700 deg C for 2 hrs and I seem to be making them worse than if I...

Thank you so much! That's what I was hoping happens. Would I use the ideal gas law across the inside and outside of the balloon to prove that mathematically? The changes in pressure would be less than a couple of psi.

That's correct!

Yes, the juice box is sealed around the straw, but the juice box is not rigid. There is no air in the juice box when exposed to vacuum. I'm interested in determining whether ambient pressure changes would affect flow from an IV bag. The IV bag gets pressurized by gravity (in my example) and...

It could pretty much be in any orientation. It will be worn by a person and they can stand up, lie down, lean sideways, etc.

Physics Forum: Can someone show me how to model, mathematically, what happens if you place a drink box with a straw sticking out of it, in a vacuum chamber and apply a vacuum?

Thanks, great idea. The problem is I can't rely on gravity since the device orientation can change.

Folks, I have an application that will require an air inlet port to occasionally be exposed to water (splashing mostly), a simple splash guard will likely not work. Are there any off-the-shelf or simple solutions that anyone can think of that can be used for keeping the water from entering...

I'm looking to create a very small expandable package to be filled with a very small amount of a volatile material at a low temperature. I'm looking to fill this package somewhere around 0.2mL of this material (propane, butane, etc) so that when exposed to room temperature, the package expands...

Thanks so much Chet! That's what I was thinking. I was thinking of treating the system as a thin-walled pressure vessel to calculate the stress on the wall at the inflated pressure. Knowing the internal pressure and assuming a thickness, that will give me a stress that I can look up to see...

Thanks Chet. It's a very complex problem. I'm hoping to get an approximation so that I can build some prototypes and then test it and optimize. Any ideas? John

Hello PF, Can anyone recommend a set of governing equations for the design of a simple elastomeric balloon that will expand to a "hotdog" shape when inflated to a certain pressure? I have the stress-strain curve for the material, I know what pressure I need to inflate it to, I just can't...

No, the increased volume comes from the expansion of the propellant inside a "capsule" made out of an elastomer. The chemicals can be from the following list at 37C:diethyl ether 1-fluorobutane 2-fluorobutane 1,2-difluoroethane What I'm looking for is a material that will expand and contain...