Gene, Inline
On 10/09/2016 01:37 AM, Gene Heskett wrote: > On Sunday 09 October 2016 01:22:28 MC Cason wrote: > >> Gene, >> >> Unless you have a good air dryer, a couple of psi of compressed air >> will cause more problems than it's worth. On a rainy/humid day, >> compressed air will be wet with water. The bellows will trap the >> water, and raise the humidity level around the ballscrew, which will >> cause premature failure, due to contamination of the lubricant, and >> corrosion. >> >> A cheap water separator will get part of the water out, but nowhere >> near all of it. A coalescing air filter can get most of the water >> out, but they are expensive, the replacement ceramic filters are >> expensive, and they require fairly constant inspection. They are used >> in paint shops as a final filter before the paint gun. >> >> Why not use a passive way to allow air in and out? You will still >> have a problem with humidity, but it will be less than with compressed >> air. https://amzn.com/B003Q6CBNY >> https://amzn.com/B008OTNGXC > In terms of either passive or thru flow, I have a small filter full of color > phase changing silica gel that I use in front of my air brush when I've air > brushing a cabinet finish. I wonder how one of those would work as an inlet > air dryer? > > They aren't that expensive, and I've baked this one out in the microwave > several times after it turned pink. It takes several days of active use > feeding the air brush with just enough air ( 7 or 8 psi )to lay on a 3 part > finish similar to Sam's (Sam Maloof) Stuff except I don't use boiled linseed, > but teak oil as the 3rd part. Dry's dust free in a couple hours. > >> BTW, airplanes use air filters that look like fuel filters. Maybe a >> cheap fuel filter for a lawn mower could be tested to see how well it >> would work as a vacuum break? Attach a hose to the outlet end only, >> leave the inlet open to free air, and connect the hose to wherever you >> were planning on attaching your air hose. Depending on use, the >> lifespan would be on the order of months, but they are cheap, and easy >> to replace (Unlike an airplane). > True about cheap, good particulate stopper after the desicant treatment maybe? > > Going back to my broadcasting experience, we tended to frown on the desiccant > to make dry air. 10 years later you can tell the diff between dry air for the > 3 psi or so pressure in the transmission lines to the antenna. Dry nitrogen > is the real stuff, copper is still bright and shiny on the inside after 20 > years, but thats north of a hundred dollar bill for a t2 sized refill. > Leakage there will cost real money. But plain dry air should outlast both me > and those bellows. As for the source of the compressed air, I am inclined to > put a cig lighter compressor in, switched on by a furnace draft safety switch > running a relay big enough to run the compressor for 3 seconds an hour. Or > something along those lines. It won't run long enough or at a high enough > pressure to squeeze the water out of the air, and that dessicant cartridge > should catch 90% of that if the humidity goes to 100%. I have a humidity > monitor out there, and can't recall ever seeing it above 77% when it was pea > soup foggy outside. > > This is in a heated and air conditioned environment. I see what you want to do now, but I don't know if blowing the bellows up like a balloon, and trying to maintain a small positive pressure on it would work. If it was practical, you would see more commercial systems using it. It never hurts to check, but unless the seal is shaped to fit the ball groove in the shaft, the groove would act as a significant leak. If you have a flow meter for either Argon, C02, or mix gas, you could use that to tell how much leakage you have. Run the nut to one end of the shaft, and tightly duct tape a hose to one side of the nut, leaving a small pocket around the shaft. Slowly turn on the gas, and see if there is any measurable flow. Saying all this, Assuming that you have 2 sets of bellows, one for each side of the nut. A sealed system with a bit of tubing that goes between the ends of each set bellows, would be a much simpler system. You would simply be transferring air from one side of the nut, to the other, without worrying about forcing air through it. If you still intend to use positive pressure, an aquarium pump with a small check valve, would be a easier, cheaper, and quieter, alternative to a tire air compressor. It would also use an ordinary wall plug, instead of using more power off of your power supply. Using silica gel would work, but it goes back to maintenance. you would be maintaining it from now on. There is no guarantee on how much moisture that gets remove form the airstream. The percentage of water that gets adsorbed is dependent on how much surface area that is available to the incoming air stream, and the volume of air passed over it. The systems I'm familiar with, used large flat pans to adsorb the moisture. After it adsorbed a certain percentage of moisture, the desiccant was replaced, and recycled by heating for a couple of hours. You don't want the desiccant to become filled with moisture, because it's efficiency goes down, as the level of water adsorbed goes up. Yours turning pink when saturated, means that it is doped with cobalt chloride. This makes it easier to tell when it needs regeneration, but makes it a bit toxic to work with. I'm familiar with dry nitrogen systems, and it would be ideal, but impractical. Even with a 300CF tank, you would be replacing it every couple of weeks or so. For dry nitrogen, 4-9's, or 5-9's pure nitrogen will cost significantly more than ordinary 3-9's gas, which can still be a bit wet. I have always wondered about the possibility of hacking a medical oxygen generator to collect the nitrogen and C02 that it normally throws away. But, even that would need additional conditioning to remove the water, and increase it's purity. Before I became disabled, the last place I worked, we used 2 rail cars of compressed nitrogen weekly. Not an insignificant cost. Many years ago, when I worked in Silicon Valley, the nitrogen we used was brought into the buildings via a 6" pipe, connected to the pipeline under the street. The infrastructure used was similar to the way that natural gas is delivered. > > Thanks MC Cason. > > I guess I'll just have to try it and see how often the compressor runs to get > an idea how leaky the bearing seals are. Not knowing, I won't shoot for any > more pressure than it takes to keep it full of dry air. >> This is what a Cessna vacuum air filter looks like (NOT cheap): >> http://www.aircraftspruce.com/catalog/inpages/Inline_airfilter.php > Doesn't look that expen$ive. > >> On 10/08/2016 10:11 PM, Gene Heskett wrote: >>> Greetings all; >>> >>> Does anyone know it the end bearings that come with a C7 grade >>> Chinese ball screw are neoprene seals or just very close fitting >>> dust covers? >>> >>> I am attempting to come up with a SWAG as to how much leakage per >>> hour there might be with 1 or 2 PSIA inside the bellows. The dust >>> cover versions I expect the pressure would just drive out the lube >>> in a few days is it was high enough to stiffen the bellows >>> noticeably. And I'd expect I'd better fit a t so I could rig an oil >>> filled vinyl manometer tube off it. Something like RCA did to >>> monitor the air pressure across the anode fins of the high power >>> tubes they used in the '60's comes to mind. Anything below 14" was >>> time to clean things, blowers and filters first. >>> >>> Cheers, Gene Heskett > Thanks everybody. > > Cheers, Gene Heskett -- MC Cason Eagle3D - Created by Matthias Weißer github.com/mcason/Eagle3D ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
