A bit of research on the history of the PV...
by, 04-29-2012 at 12:33 AM (407 Views)
Over on my "other" blog, (concerned with issues of men's fashion and called Dress Like A Grownup!,) I've been doing a month-long series on the history of tobacco use, culminating with the PV. In the process, I've discovered some interesting things that I think all of us would find useful in describing PVs to our politicians and lawmakers. Here're some excerpts from that blog entry, edited down to eliminate both the fashion-oriented content, as well as the basics, that we on the ECF already know. All of the links are clickable to the source material. Although some of this information is on the ECF already, much isn't, and not all in one place.
[We'll skip ahead, past the story of Lik Hon's inventions and patents, and a brief description of the PV's operation and the terminology involved.]
...Several things are immediately apparent even with this bit of information.First, this is not a cigarette in any sense of the word. It contains no tobacco, does not combust anything, and does not produce smoke. In fact, even calling it an "electronic cigarette" adds much to the confusion surrounding the technology...
...Vaporized propylene glycol is in fact the very technology that is used in fog machines; so this is not tech that is breaking any new ground -- merely its utilization, and its battery-powered miniaturized scale.
Let's look at propylene glycol for a bit -- it has an interesting history, it's at the heart of the PV, and it holds some fascinating surprises.
Also called 1,2-Propanediol or C3H8O2, propylene glycol is a very versatile substance, used as a food preservative, an additive for food colors and flavorings, a solvent for medical preparations, a moisturizer, and a carrier for perfume oils and soap bases. Its pharmacokinetics show it to be also quite safe. It is metabolized in the human body largely into pyruvic acid and converted to energy. Propylene glycol does not cause sensitization and it shows no evidence of being a carcinogen or of being genotoxic.
But that's nothing compared to a discovery made in the late 1930s, that it was also a very effective germicide!
A study at the University of Chicago by Drs. O. H. Robertson, Edward Bigg, Theodore Puck, Benjamin Miller, and Elizabeth Appell, called THE BACTERICIDAL ACTION OF PROPYLENE GLYCOL VAPOR ON MICROORGANISMS SUSPENDED IN AIR proves the germ-killing properties of propylene glycol, and is very interesting reading for the technical-minded.
Time magazine ran the story, called "Air Germicide," on Nov. 16, 1942. [The article is then excerpted.]
patent on the method of sterilization of air by vapors in November 1943. The above illustration is the method of vapor production used in the initial experiments. One can easily discern the key components of the modern PV even at this early stage: the syringe acts as the cartridge, the atomizer (as today) is the wick wrapped in an electric heating element. Air is drawn over the atomizer, mixing with the vapor, and into the test chamber.
Propylene glycol was planned to be used in large-scale air disinfection in hospitals, until it was discovered that ultraviolet light gave the same result...and it was much easier to wire up a simple light, than devise a system to pump vapor through an HVAC system. So the concept wasn't pursued, although Dr. Bigg patented an apparatus that did just that in March of 1944. Glycol and water were heated to their vaporization points together in a tank by an immersion coil, providing humidification as well as sterilization. Since water and glycols vaporize at different rates, an ingenious device using a thermoswitch automatically regulated the water to maintain the concentrations in equilibrium.
patent for an improved distribution system, which wasn't issued until 1950. In this version, the glycol is vaporized indirectly: instead of direct contact with an atomizer, glycol is fed at a controlled rate onto a series of baffles in a branch line of ductwork. The air in the branch line is electrically heated to vaporization temperature, and is drawn up past the baffles by way of a venturi in the main duct, vaporizing the glycol as it passes.
patented a method of localized vapor production that began to look like a large version of a PV. In fact, it is by very definition a "personal vaporizer." In this instance, the propylene glycol is fed from an exterior reservoir into a shallow dish, that is in contact with an incandescent light bulb and heated to vaporization temperature. Convection currents draw air over the dish and up the chimney, ostensibly into a hospital room. Apparently it worked very well; the inventor makes mention of the visible "fog" that it produces.
patented a design for a "smokeless non-tobacco cigarette," that at first blush would seem to be the progenitor of the modern PV. In fact, many people mention this patent in the same breath with PVs, which is why I'm including it here. It isn't related to the modern PV, though. Instead of the atomizer/glycol arrangement that is at the heart of a PV, this design used a long, thin incandescent bulb or vacuum tube (!), rather improbably powered by a tiny button-cell battery to merely heat the air that has passed over a saturated "flavor cartridge" filter medium. Nowhere in the patent is propylene glycol mentioned -- and the heater would be insufficient to reach vaporization temperature in any case.
All the components of the PV were thus proven and firmly in place since 1940, but the technology to make it small enough to be truly personal and portable didn't exist until now. And now you see what Mr. Hon happened upon -- not merely a nicotine replacement, but a personal, portable germ-killing air sterilizer! Could there be a better accessory for the twenty-first century? The problem is, the marketing and advertising is all wrong. The PV is the diametric opposition to cigarettes -- vaping makes you healthier! -- but the nicotine issue has regulating agencies in a quandry, since they are unable to divorce nicotine from tobacco.
In fact, e-juice requires no nicotine at all; it is perfectly possible to vape pure propylene glycol. There is no psychopharmalogic effect, no flavor -- just a cool misty vapor that, in itself, is rather refreshing...
[What follows is more sartorial stuff, a bit of direction concerning getting started in vaping, and a few good words and links directed to the ECF.]
...Do I think these PVs are a world-altering paradigm changer? You bet. But not because they are nicotine replacement therapy. That's looking through the wrong end of the telescope. Dr Oswald Robertson may not have foreseen a world in 1943 where "mankind could live...continuously in an atmosphere of glycol vapor," but that future is here, now, and we can all take a swipe at airborne respiratory diseases. If you're not a smoker, just don't use the nicotine juice. Vape all you want of the most delicious juice you can mix, and look stunning while doing it. It's the "new smoking," and it can be every bit as elegant as it was in 1940. And a whole lot healthier.