![]() I guess part of my confusion is, if these things exist, why is there even a ? the PSS they sell are 10 times more expensive, much bigger. The Style 4 is a little different, and yes is designed more for linear, although may work, this style 2 probably will work better for what i'm doing. I just pulled it out and now realize it was designed specifically for rotary motion. I actually have a style 2 (Part # 9281K71) which I bought a long time ago and actually forgot I had eheh. They are the standard for many chemical pumps intended for leak-free operation. I have also seen good reports of ceramic valves in tough industrial applications on pump shafts. ![]() One high use tap leaked because the end stop got flogged and allowed the closure to overtravel. ![]() I have never needed to replace a valve through seal wear since going to them 10 years ago. ![]() I only use ceramic valves for household taps. You could consider a rupture disc, weak point in the casing or relief valve that vents high pressure out of harms way. If you use the li-ion batteries then even the stabilised ones that A123 make will produce a nice explosion if there is an electrical fault in a sealed chamber. I would even fit a small pressure guage until I was confident. Almost impossible to get a submersible properly sealed the first time around. Not high pressure but enough above atmospheric to produce tell tale bubbles when initially immersed. One of the things to do is to pressurise the unit with air. So i'm just wondering what everyone thinks of those, they worthless or they might work? I don't even mind if they wear out after 10 hours, or 1 hour, would be better space wish then the other thing. These are dramatically cheaper then a PSS and would require tons less space,and space is getting cramped. They do say 250psi for slow rotary motion, although "slow" doesn't really mean anything, wish they would of had an rpm with that. Now honestly from the mcmaster page I can't even tell if these are meant for spinning drive shafts, or shafts that move in and out, but clearly they are meant for shafts that move. They are spring loaded and will push out on the shaft and on the inside. Now, I haven't received this seal yet (I should tommorow), but does anyone think these types of seals are any good: and search for: 13125K84 I know it's been a while since my last post here, but wanted to get some more advice/information on this subject.įor my project I went ahead with the packless shaft seal, from Now this works but i'm hoping I can come up with something that is a little more compact then this solution. My seal needs to overcome this pressure difference and not allow anything through, as you may have guessed my drive system will be electric so I don't want it shorting out the motor/electrical system. See, on the surface, I think that would work, heck I think one bearing would work, but I want to have the ability to dive, and 33 feet down will create a 14.7/1 bar differential in pressure between the outside and the inside of my device. I hope that made sense, if not i'll try to throw together a picture later. Waterproof grease would fill the interior chamber to it's utmost capacity, and of course it would be used everywhere else as usual. O-Rings would be places where they could be to seal the bearings to the axle. There would be a space inbetween them and the section in the middle would be completly sealed off as well. I want to use 2 double sealed ball bearings (for double protection) on the shaft. Here was my plan, I have no picture so i'll try to desribe it, it's not really that complex. Obviously it hooks upto a propeller before that, but inbetween there what is the standard approach for making this rotating axle not take it water? I have some double sealed bearings from mcmaster which appear to be air-tight, the RPM is within acceptable range. I wouldn't say i'm designing a boat, but i'm toying around with a water propulsion system, a handheld one, and i'm trying to figure out how to seal the drive shaft to the outside.
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