Using an air tank for vacuum?

These venturis are very noisy and they take a lot of air. For soldersucking, you don't need high sustained volume. What you need is a pulse, like the trigger-actuated hand-held single-shot piston pump "Soldapullt", though perhaps a bit longer in duration. I think a small reservoir like a 16.4 oz propane bottle very near the point of use would do the job. It could also accumulate the crud because it's easily and cheaply replaced, and a 16.4 oz reservoir would hold years worth of sucked solder. You might want a larger reservoir mounted out of the way somewhere. Some restriction between that and your pulse reservoir (a point-of-use vacuum capacitor, if you will) might actually be beneficial. You get your shot, then it takes a second or two to suck back down from the larger remote reservoir which is cyclically maintained by the pump.
Teflon tube (drilled rod) works well as a sucker nozzle. You'll want a poke rod to clean it out periodically.
Braid works better for surfacemount, but a sucker really does work well for clearing out holes in thru-hole boards.
Reply to
Don Foreman
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Thanks Don. Makes perfect sense to me. I do, in fact, have a soldering/desoldering station (A.P.E. SMD2000M, equivalent to Pace 2000), however its vacuum feature leaves much to be desired.
What I am going to try to do is, get the DV-142 deep vacuum pump that I won in a military auction (have not picked it up yet, but hope that it is good), connect it to a vacuum tank, add a foot actuated air valve, and connect that to the desoldering tool. It is a nice tool with a heated tip with a hole, and a trap for solder. What this would change is that instead of a pump on the station, the air would be sucked by the air tank when the foot pedal is depressed and the valve opens.
I am pretty much set on using a propane tank as a vacuum tank. I already have a propane tank, after all, that I do not need (I have two in fact). I learned that they have 1" NPT openings, where the propane valve is screwed in, so it would be easy to change for a 1/4" npt tee with a vacuum gauge (already have one), a line to the pump, and a line to whatever would be sucked.
I will also try to find a vacuum relay of some sort, so that the pump is not running needlessly -- only when the pressure inside is higher than a set limit. Have not found one yet.
I appreciate your comments.
i
Reply to
Ignoramus2963
The usual setup when using venturi vacuum generators (Piab is on of the large mfrs -
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) for parts handling in automated machinery is to switch the air supply in order to turn the vacuum on and off. This minimizes the problems of high air consumption and noise and may make a venturi acceptable for desoldering.
It's been several years since I've had occasion to use a Piab unit, but I believe some models provide for an external surge tank that kicks in when the air supply is turned on. Details might be on Piab's site.
Ned Simmons
Reply to
Ned Simmons
I chopped a propane tank up to make my first vacuum chamber for coating telescope mirrors. Worked fine at 2x10-5 torr (a pretty good vacuum, at least good enough for my needs).
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More information on my web-site,
Take Care, James Lerch
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(My telescope construction, Testing, and Coating site)
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(My 15Kw generator project) Press on: nothing in the world can take the place of perseverance. Talent will not; nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated derelicts. Persistence and determination alone are omnipotent. Calvin Coolidge
Reply to
James Lerch
Looks nice. 2x10-5 torr is the same as "20 microns", is that right?
The pump that I will soon pick up, is supposedly able to get 25 microns. I am aware that I do not need that for solder sucking, but it may be helpful in other instances.
i
Reply to
Ignoramus19736
SWITCH I will assume you mean't, of course you can or may need to use a contactor or relay as well.
Good ol' Mcmaster has switches for vacuum situations, but they are listed under "Pressure" switches.
The most reliable are the Bourdon Tube type with a mercury bulb, but they are not cheap.
The "Snap Switch" type are best installed on something that rattles or shakes as sometimes they will stick. Nothing a good kick doesn't take care of, but if you leave the shop for a week and forget to unplug the pump, you might find it melted down when you get back (don't ask how I know).
EBAY often has bourdon tube units for around $25.
Grummy
Reply to
grumtac
A few projects ago I was looking to cast some clear resin, and was looking for a vacuum chamber. I found an old 1 gal. paint pot at an auction. I changed some fittings so as to be able to use my automotive A/C gauges and vacuum pump with it. The pot turned out to be an acceptable vacuum chamber for my project.
John Normile
Reply to
John Normile
No.
20 microns is 20 milli-torr (2x10-3 torr) 1 torr = 1mm mercury. 760mm mercury = 1 atm.
You can't measure it anyway unless you have a thermocouple vacuum gauge.
I have two welch (1400 & 1405) two stage pumps. Getting down to under 10 milli-torr with a mechanical pump is a challenge no matter what the specs are.
Rule #1. Everything leaks below 1 torr Rule #2. Everything leaks even more below 50 milli-torr
For example, I hooked up a short length of 3/8 automotive hose to the 1400 pump. It could easily get to 100 milli-torr but not much lower. Dead headed either pump will get a litle under 10 milli-torr even though the spec is closer to 1.
Getting vacuum down in the 10-5 torr range is getting pretty fancy requiring a diffusion pump (or turbo pump) and maybe even a cold trap. Now you need yet another vacuum gauge to measure levels this low.
Everything you ever wanted to know can be found with a google search for sam's laser and vacuum page.
chuck
Reply to
Chuck Sherwood
Well?
Did the air tank collapse??
We're all waiting with bated breath!
Reply to
Rex B
I use a Vac-u-vin coffee jar with a hand pump made from a rubber cork.
Works just fine for degassing PU and epoxy resins!
Reply to
Andy Dingley
I would try to use a small glass jar as a vacuum chamber. (and a steel plate with a gasket as the cover)
i
Reply to
Ignoramus19736
Thanks Chuck. It was educational and I saved your post. Practically speaking, I doubt that I would need vacuum beyond 25 microns, and for now I would be satisfied with much lower vacuum, like 20 inches HG for desoldering. I may play with making freeze dried food, and there I likely need a vacuum that is not particularly deep.
i
Reply to
Ignoramus19736
Well wrapped with tape to control the fragments if it implodes I hope, or better enclosed in a shield as well :-)
Reply to
Ian Malcolm
Thanks Grummy. Looks like I won something for $12.50 or so, I'll see if this thing fits my application. If not, I will look for these bourdon tube units.
i
Reply to
Ignoramus19736
You'll probably find a pressure switch on EBay. Failing that, you can get a 0 to 100 kPa (0 to 14.7 PSIA) sensor from DigiKey for $7.88. MPXM2102AS-ND This is an absolute pressure sensor, measuring against an internal vacuum reference so you would turn on the pump when pressure in your reservoir rises above x PSIA (0 PSIA being a total vacuum) and turn it off when it goes below x - hysteresis. You could set these pressure trip points to anything you like with fixed resistors or trimpots.
Other elements needed would be an instrumentation opamp (INA126, $2.25), a 12VDC supply, a solid-state relay or a transistor and relay, maybe an LM393 comparator (42 cents) and some resistors. Maybe a 3-terminal voltage regulator for 72 cents. The whole works shouldn't cost $15 plus the relay which you probably already have.
Reply to
Don Foreman
Thanks Don. I have some parts already, such as comparator chips and an SSR and 12 vdc supplies.
I won something on ebay that is called Barksdale Pressure Switch, D1H-H18SS, 1/4 inch SS NPT, .40 - 18.00 PSI range, 1 setting, you can see it and the datasheet at
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I appreciate the suggestion though, I will save your post for the future.
i
Reply to
Ignoramus19736
According to Ignoramus19736 :
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And you *don't* want to use the same pump for food freeze drying that you use for desoldering.
The desoldering will get at least some microscopic bits of lead into the plumbing.
Bleeding back to atmospheric after freeze drying may transport those into the food.
And I really think that using the kind of pump which you have purchased (and not yet received, I believe) for de-soldering will lead to contamination of the pump oil. I would suggest a Gast rotary vane style pump for that, It runs dry, and doesn't have oil to get contaminated.
Good Luck, DoN.
Reply to
DoN. Nichols
That's a good point, but, I think, properly placed filters and ball valves should take care of this.
i
Reply to
Ignoramus19736
Please don't. Imploding glass containers are very dangerous. If you must, put it inside a wooden box or something to contain the fragments if it explodes. If you want a cheap bell jar, fisher scientific sells some small ones for under 50 dollars.
chuck
Reply to
Chuck Sherwood
That should work. With that small differential your pump will probably cycle with each hit of the soldersucker valve.
A half-vacuum (7 PSIA) is plenty to suck solder.
Reply to
Don Foreman

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