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I live in Maine. Mosquitos also live in Maine. Many, many of them. Mosquitos also really like me. I must use up plenty of oxygen and exhale a great deal of carbon dioxide because that's what attracts mosquitos. Strangely, their bites don't irritate my skin much -- rather, the buzzing around my ears and eyes drives me insane.
The device to combat these tiny terrorists is the "Mosquito Magnet", The device uses a bare trickle of LP (Liquified Petroleum) gas from a 20 pound cylinder -- your basic grill propane tank -- to emit a small but constant amount of Carbon Dioxide into the air. It is roughly the equivalent of of a small animal breathing. A 20 pound cylinder lasts about a month. The device also uses a chemical scent to attract the little bugs most of the time (in some states, a kind of mosquito avoids that smell so they don't use it there). By operating all the time, day and night, the device really does attract a huge number of the little things from the area and captures them by simply using a fan to suck them in when they get close enough to the source of the CO2 and the attractant.
If used early enough in the season, they claim it can capture enough of them to interrupt the breeding cycle in your little area and give you a lovely mosquito free zone. And it actually works. When it works.
Here's the problem. This device is extremely sensitive to any contamination in the fuel by regular air. The smallest amount of regular air in the tank will cause the Mosquito Magnet to shut down with its flashing little red light indicating a problem. The manufacturer insists that you have your cylinders "purged" when you buy them (essentially filled and emptied in a way that LP gas displaces any regular air) and that you never ever use cylinder exchange services like Blue Rhino.
To me, this is utter bullshit. Services like this allow you to replace your empty cylinders by swapping them for a full one and paying for the fuel. This beats waiting for the fuel company or local U-Haul dealer or whatever to be open and having a qualified technician available to fill your own tank and charge you for the fuel you add. It's not much more expensive if you assume that your own tank is truly empty. Of course, it usually isn't. I suspect a good portion of the profit Blue Rhino makes comes from not having to fill them all from empty each time. That's fine with me, it's a good business model. Of course, it's very unlikely that Blue Rhino would purge every tank every time --that would waste thousands of dollars of fuel every day and would be very bad for the environment on top of being generally unnecessary. A little air in the tank doesn't cause your grill a problem, as the flame just burns it off.
Needless to say, my Mosquito Magnet has been temperamental and unreliable. Just when you think its working, you swap bottles and it stops again.
Last night I came up with what I hope is a simple, elegant, and brilliant fix. Through my hazmat training, I know that LP Gas has a specific gravity of 1.5 -- it's about half again as heavy as air. If it leaks, it will tend to pool at ground level making quite a dangerous situation. The LP fuel in one of these tanks is liquified by being under pressure. As you open the valve and release some of the gas, the pressure drops and some of the liquid fuel boils (literally) back into gas. There will always be a pool of liquified petroleum and a gas vapor area on top. I've actually seen this in seminars where they use a glass bottle to hold the LP so you can see the bubbles boiling off.
What I've decided to try is simple. Attach the LP cylinder that was too contaminated to use on the Mosquito Magnet, to the gas grill. Let it settle for a few hours. This should cause the heavier LP Gas to settle into a lower layer with the lighter regular air floating at the top of the tank. Slowly open the value and light the grill. Using the grill at it's lowest setting that will stay lit, cook something. A few minutes use should be enough. The air contamination won't bother the grill any -- the volume used is higher and air will just burn off. I suggest using the grill at it's lowest setting, as that will boil off the LP Gas more slowly and should produce less convection in the cylinder so that the air at the top doesn't mix back in so much.
If my theory holds true, I expect two things:
1. The partially used tank on my grill should power the Mosquito Magnet perfectly. So far, that has proved correct.
2. The contaminated tank, once used on the grill, should also provide excellent fuel for the Mosquito Magnet when the current tank runs dry.
We'll have to wait a few weeks for the results.
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LP is heavier than air, and the valve is at the top, wouldn't the easiest
solution be to simply mount the cylinder upside-down, so that all the
uncontaminated LP is nearest the valve, and the air is trapped at the bottom
(now top) of the tank?
Or am I just demonstrating a profound ignorance of hardware hacking here?