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armedandsafe
10-17-2012, 12:06 AM
I can find many hand pumps for pulling a vacuum in a plastic sack, vacuum seal bags or in glass jars, but nothing that looks practical for 5 gallon buckets. The larger ones look like they are going to get into the 3 digit dollar range, which is not good at this time. The buckets are full of things like grains, cloth items, light tools and such. What I want is enough vacuum to firmly seal the snap-on lid down on the gasket.

I don't have the valve figured out, yet, but I think a flap valve style thingy would be fabricated fairly easily. Or, perhaps a standard tire valve, since I don't need a full vacuum, just some reverse pressure.

Pops

macona
10-17-2012, 12:15 AM
One od the cheap harbor freight air conditioning pumps would work. Or just about any diaphragm pump.

The Artful Bodger
10-17-2012, 12:19 AM
is 17 - 20 inches of mercury enough vacuum? I think you can get that from a tap on the intake manifold of a petrol engine at idle.

Optics Curmudgeon
10-17-2012, 12:33 AM
Google "aspirator pump"

CCWKen
10-17-2012, 12:36 AM
Or just heat the contents and bucket to about 200 degrees then put the top on. When it cools, it will be under vacuum. So much so, that you'll probably have to punch a hole in the top to open it. The bucket will handle the heat but you have to watch the contents. You probably wouldn't even need to go that high of a temperature. Maybe 50% over ambient.

darryl
10-17-2012, 01:04 AM
I experimented once with surgical tubing and air pressure. Apply pressure, and at a certain point, the tubing suddenly goes from swelling slightly to a much larger diameter. If you mounted it within a cylinder that has that same inner size and shape, the first expansion will drive out all the air inside the cylinder. Then as you remove the air pressure, the tubing will collapse and draw a vacuum in the cylinder. With suitable in and out valves, and a suitable valve to control the air, you could generate a vacuum.

In practice, you would keep the size of the cylinder enclosing the section of surgical tubing to something smaller than the expanded size of the tubing. That way it would probably last quite some time, plus having a smaller final diameter it will have more 'pull' when contracting.

This is a way of getting a pretty good vacuum by using your compressed air system. Probably not super efficient, but very compact and no rings to leak, oil to fill, etc. In and out valves could be simple- the main item would be the pressure side valve to alternately pump, then release, pump, release, etc.

kd4gij
10-17-2012, 01:20 AM
A shop vac should work fine for that.

Paul Alciatore
10-17-2012, 01:25 AM
A shop vac should work fine for that.

I was wondering about that. K.I.S.S.

Forrest Addy
10-17-2012, 01:57 AM
Plastic pails with sealable lids don't do vacuum very well. The polypropylene wants to yield and will in hot weather relieving the internal vacuum to a certain extent.

Oxygen and light is the enemy for long storage items, particularly food. Why not a nitrogen purge? Set a small container of LN2 in the bottom of the pail, fill it with your goods and a dessicant bag, and place the lid (which with a brick on it to make a very low pressure check valve) without sealing it. After a time the LN2 will evaporate diffusing through the contents, sweeping up the air and O2 ahead of it. and escaping the lid. After a few hours seal the pail and you're done.

Use a food grade black pail and you will be certain of no funny smells or flavors and no light degradation. When properly sealed they are DOA certified to seal tight for food containment.

Maybe there's a link here: http://www.google.com.bz/search?hl=en-BZ&source=hp&q=food+grade+5+gallon+pails+with+lids&gbv=2&oq=food+grade+gallon+pails&gs_l=heirloom-hp.3.2.0i8j0i8i30l2j0i22l7.1422.13250.0.19859.23.2 2.0.1.1.1.625.4374.3-3j6j1.10.0...0.0...1c.1.a_pbacSaNMc

If not contact the survivalists. They may be nuts about some things but they have long term food and valuables storage pretty well worked out

vpt
10-17-2012, 07:59 AM
The pail will fold/crease/dent in on itself over time. I forget for what (I think bleeding brakes or sucking oil out of a crankcase) but I tried pulling a vacuum in a pail before, it started to work then I had a mess on the floor.

This is unless you plan a very little amount of vacuum in the pail.

Weston Bye
10-17-2012, 08:24 AM
I agree with Forest, but also would speculate a little further that vacuum packing for anything but metal cans and mason jars could be problematic.

At work we are dealing with sealing an electronics cavity in a part that lives in a wet environment with wide temperature changes. The part involves metal terminals and other components passing through glass-filled nylon overmolding. Hermetic? Not so, even though the nylon is in intimate contact with the metal parts.

I relate this only to illustrate that maintaining a pressure equilibrium between inside and outside has a better chance of preventing infiltration of undesireable substances. In preservation, removal of the oxygen and prevention of its return is the goal. Secondary but also important, is the prevention of infiltration of unwanted chemicals, bacteria or mold spores.

A sustained vacuum in all but the most impermeable container is working full time at trying to suck in air, moisture and opportunistic contaminants. The two mechanisms working to force air in (and out) are variations in temperature and barometric pressure. Not much can be done about the latter, so the the usual advise about storage in a temperature-stable environment is about the best that can be done.

Back to my problem with the water infiltration on the part I described: I have suggested a diaphragm be incorporated into the design, allowing the pressure inside the cavity to remain equal with the outside, the diaphragm flexing with the pressure variations. This would prevent the moisture from being sucked in when the hot part and the air inside the cavity is suddenly cooled by a splash of water. So far, the proposal has been rejected. Perhaps I will have to build a working proof-of-concept to convince the doubters. Or disabuse myself of the notion that it is possible...

vincemulhollon
10-17-2012, 09:36 AM
The buckets are full of things like grains, cloth items, light tools and such.

Ah I see we have some interests in common. Word to wise is you can't pull a vacuum on those things. O2 permeable. Ruins the buckling strength of the buckets so you can't stack them anymore, or even worse they collapse randomly in the future. Pitifully weak under negative pressure. Seal usually not designed to hold anyway. Also a partial vacuum will NOT prevent insect eggs and mold from growing in the grain. So you need to purge the air with pure nitrogen, or welding argon, or CO2 from dry ice. Propane or helium could technically work but are really dumb ideas.

Supposedly the best way to do it is to stick a hose to the bottom of a mylar (O2 impermeable) bag, fill with grain, wait until the "air" coming out of the bag blows out a candle, then blow a little more in, then Finally "vacuum" pack which firms up the bag, takes up less space, and makes it visually obvious there's no hole in the bag, and sucks any remaining air out. Mylar bags are NOT rodent proof, but 5 gal buckets more or less are rodent resistant. Own a cat (or let a cat own you, as seems the case with felines)

Its not entirely unusual to spend more money on mylar / O2 packs than on the grain.

Also before you store your "tools" check for oil/grease compatibility. Some cleaning solvents etc will weaken the plastic. If it cannot be shipped in bulk in a 5 gal plastic bucket, I would not apply it to "tools" and then seal them in a plastic bucket, the mfgr knows something... You can buy 5 gallons of WD-40, shipped in a STEEL container... that says something.

Never store anything but food in a food container. Mylar or no, theoretically impossible yeah blah blah, regardless of all the arguments if you store "tools" in a bucket with grains, the grain is going to eventually taste like cosmoline.

Rosco-P
10-17-2012, 09:37 AM
The buckets are full of things like grains, cloth items, light tools and such. What I want is enough vacuum to firmly seal the snap-on lid down on the gasket.

Pops

Based on what you are preserving, I'd be searching on one of the "Prepper" type forums. Long term storage of perishables is is their goal. http://americanpreppersnetwork.com/

vincemulhollon
10-17-2012, 09:46 AM
At work we are dealing with sealing an electronics cavity in a part that lives in a wet environment with wide temperature changes. The part involves metal terminals and other components passing through glass-filled nylon overmolding.

Oil immersion? A guy I know did that with wifi gear. Note that "all" electronics are distilled water/ethanol compatible because that's how the flux is washed off, but only some plastics are mineral oil compatible, not unusual for the plastic sleeve to dissolve off electrolytic caps, or the ink to literally wash off and deposit elsewhere. If you're doing RF stuff this will mess with the dielectric constant but then again it might all work anyway. If you're doing power stuff try to pick an oil that won't burn, there was this amazing polychlorinated biphenol compound but it turned out to have serious other issues.

Water will accumulate under the oil. It might take decades to fill 6 inches of slop space.

You can't keep liquid off rough environment stuff. However, you can pick the liquid and almost anything is better than water.

rowbare
10-17-2012, 10:23 AM
Look into oxygen absorbers. Put a couple in each mylar bag. For larger bags, use one of those air activated hand warmers, they do the same thing.

Another option is to take your stuff to one of the LDS canneries. They have them all over the country: http://www.utahpreppers.com/utah-bulk-food-suppliers/us-lds-cannery-locations/. You can pack your stuff into big #10 tin cans.

bob

TheAndroid
10-17-2012, 12:27 PM
One od the cheap harbor freight air conditioning pumps would work. Or just about any diaphragm pump.

Save your money. They are simple venturi vacuum generators. Find a block of metal, drill a hole through it, then drill an intersecting hole in the side at an angle (45-30 degrees). Compressed air through the main hole, vacuum (out?, in? hmmm.) from the other.

Weston Bye
10-17-2012, 01:07 PM
Oil immersion? A guy I know did that with wifi gear. Note that "all" electronics are distilled water/ethanol compatible because that's how the flux is washed off, but only some plastics are mineral oil compatible, not unusual for the plastic sleeve to dissolve off electrolytic caps, or the ink to literally wash off and deposit elsewhere. If you're doing RF stuff this will mess with the dielectric constant but then again it might all work anyway. If you're doing power stuff try to pick an oil that won't burn, there was this amazing polychlorinated biphenol compound but it turned out to have serious other issues.

Water will accumulate under the oil. It might take decades to fill 6 inches of slop space.

You can't keep liquid off rough environment stuff. However, you can pick the liquid and almost anything is better than water.

In the application I described (sorry I can't be more specific) keeping the oil in would be just as difficult as keeping the water out. Current remedies are trending toward potting, as a patch rather than a solution. Messy, difficult to manufacture, costly.

Guido
10-17-2012, 01:11 PM
http://i126.photobucket.com/albums/p86/Guido_album/Venturi_sectionJR.jpg

armedandsafe
10-17-2012, 03:39 PM
I was looking at the AC pumps, but wasn't sure they would be clean enough for food stuffs. I'll research that.

17-20 inches will be more than enough. The problem with using a petrol engine is only that I wish to use electricity. The scenario I'm looking at says that we will lose petroleum before we lose electricity, as our E-power is hydro.

The least expensive aspriator pump I see on a minimal search is $152. I'd much prefer to stay well below that.

Heating the bucket is a thought I had not had. Some contents will be sensitive to that, but it is a thought.

Surgical tubing for an ~11" diameter bucket seems quite large, for the sizes I've seen. However, a baloon would probably work.

I've thought about the shop vac and might go that route. However, I am hoping for something much smaller in size, for portability.

The buckets I'm using are white food grade buckets I get from a friend at a local drive-through for $1.00 each, including the lid. I'm in contact with a number of survivalists, as my wife's sister is in such a group. I've several ideas already from them. I am also familiar with several of the "prepper" groups, but thought I'd ask for advice about a mechanical device from people more knowledgeable in such items.

LN2 doesn't appear to be available in this little town. I've thought about using dry ice, but the termperature extreme bothers me and the availability in small quantities is iffy in this area.

The amount of vacuum I _need_ to pull is really rather small. I think 5psi or so would be enough to seal the soft lid ring enough to do the job. I have had some buckets with a lid flexible enough that leaning on it while lifting one edge will produce enough vacuum to obtain a good seal. The ones I'm getting lately hafe much harder lids and sides and I don't weigh enough to get any appreciable vacuum.

Weston, when working QC at Daytron, we would pressurize certain parts of the radios to insure against ingress of moisture. We used dry CO2 to fill the containers to about 1.5 atmosphere pressure after mounting the item in the radio and QC testing its operation. I played with a flexible diaphram to neutralize temperature/pressure changes but that was unsuccessful on the small parts.

Vince, I am well aware of the need to separate items, each type to its own container. The storage I'm working with right now is relatively short term, in the range of a year or two, so I can afford some of the problems encountered in truly long term storage. Think of storage while the dwelling is vacated for that long. We are owned by 7 cats at the moment, so rodent problems are few. ;) The "tools" I'm storing really don't need the vacuum so much, as they are immersed in oil. The ones which I do want to get a vacuum on are the electronic test instruments. I'm sealing them in double mylar, but want the vacuum as a bit of extra insurance. The food stuffs are double mylar bagged and vacuum sealed with a standard "Seal-A-Meal" processor.

Guido, I'm going to have to study that a bit. I think I understand the process, but I'm not sure, having just glanced at it. I'm thinking of a Schrader or Presta valve (poppet valve) thingy at the moment. On that note, I'm even thinking of small bicycle tubes. Filling the tube inside the bucket would drive out much of the air. Releasing the pressure in the tube after sealing the lid would then draw a vacuum. I'm not comfortable with the idea of a rubber tube in with food stuffs, however.

Thank you all for your comments and advice. When I actually get around to doing this project, I'll post a progress report.

Pops

RussZHC
10-17-2012, 04:07 PM
Bicycle tubes could pose a cleanliness/contamination issue...most I have seen are coated with something to prevent them sticking to themselves (?, really have no clue, could be anything from rice flour to chalk but given most are imported from south Asia, I would question it just on consistency of what it is, or is not. At the very least it could add a cleaning step to the process.)

armedandsafe
10-18-2012, 02:32 AM
Good point. I agree with that. I wouldn't use them on food stuffs, but might on other items.

Duffy
10-18-2012, 11:07 PM
Two points:- first you are not evacuating an EMPTY bucket-far from it. Therefore the pump does not have much work to do.
Second, if you ever noticed the gooseneck faucets in a chemistry lab, (at school?) The little spigot on the side is the suction connection of a VERY efficient little aspirator. Where I went to school, the tap water in winter was a constant 39*F. With normal city water pressure, those aspirators would pull over 27" of vacuum. In summer, with higher water temperature, not so much.
That is not an estimate, by the way; I measured it!
A plumbing supply should carry them.