Vaporizer (inhalation device)
A vaporizer or vaporiser is a device used to extract for inhalation the active ingredients of plant material, commonly cannabis, tobacco, or other herbs or blends. However, they can be used with pure chemicals when mixed with plant material (e.g. nicotine-free tobacco).
Vaporizers contain various forms of extraction chambers including straight bore, venturi, or sequential venturi, and are made of materials such as metal or glass. The extracted vapor may be collected in a jar or inflatable bag, or inhaled directly through a hose or pipe. With little to no smoke produced and cooler temperatures, less material is required to achieve a given level of effect. Hence, the irritating and harmful effects of smoking are reduced, as is secondhand smoke.
E-cigarette or Electronic Cigarette is used to designate a subcategory of vaporizers designed to replace cigarettes. E-cigarettes make use of E-Liquid: flavoring and nicotine dissolved in a solution of vegetable glycerine and/or propylene glycol. Using E-cigarettes, as opposed to lit cigarettes, is considered to overall be a safer experience for both users  and those nearby.
E-Liquid can be safely vaporized at 125-150C, the ideal vaporization range for tobacco. Some E-cigarettes have been found by researchers to vaporize (reach coil temperatures) above this temperature, releasing acrolein (the byproduct of heating the e-liquid media at high temperatures). This information presents safety concerns and was accompanied with suggestions for safety certification, but most e-cigarettes are successfully engineered to never exceed more than 150C. As well, the carcinogens produced were 8x less than found in regular cigarettes. 
Because of the benefits of vaporization over smoking, e-cigarettes are often regarded among the medical community as both as a valuable harm reducing alternative to lit cigarettes and as an effective smoking cessation aid.
Many of the cannabanoids in cannabis buds vaporize at above 180 C; THC, the principle psychoactive ingredient in Cannabis, vaporizes at 157 C. However, most e-cigarettes vaporize at or near 125 C, for power efficiency and so as to not affect flavorings designed for the typical e-liquid temperature range. Because of this, most retail e-cigarette devices are of no or limited use in vaporizing cannabis.
Vaporizers used for Cannabis are often vaporizers that have been specifically designed for dried, ground Cannabis. Some advantages of this are some vaporizers allow for vaporizing the full spectrum of cannabanoids, and dry vaporizers avoid having to leech the cannabis chemicals into E-liquid.
Few vaporizer studies or reviews have really addressed the quality of the vapor extracted and delivered; instead, focus has generally been on the mode of usage of the vaporizer. There are 483 identifiable chemical constituents known to exist in the cannabis plant, and at least 85 different cannabinoids have been isolated from the plant. The aromatic terpenoids begin to vaporize at 126.0 °C (258.8 °F), but the more bio-active tetrahydrocannabinol (THC), cannabidiol (CBD) and cannabinol (CBN) do not vaporize until near their respective boiling points: THC 157 °C (315 °F), CBD 160-180°C (320°F-356°F), and CBN 185 °C (365 °F) As typical consumer vaporizers start with a small quantity of plant material at room temperature, extraction and delivery of the bio-active vapor is initially slow as the plant material must first pass through the temperature range that produces the aromatics before reaching the target extraction temperature; as the plant material temperature rises, the vapor becomes increasingly bio-active, but minimally aromatic, as most of the aromatics will have already been released.
Vapor preferred by many users is higher in concentration and aromatic density due to the increased rate of extraction and smaller sample size. Bag capture vaporizers tend to be slower in extraction rate, which allows the attainment of fuller spectrum vapor, but are less convenient to use.
Studies have shown that vaporizing cannabis exposes the user to lower levels of harmful substances than smoking cannabis. Substantial reductions were also found for the M1-volatizer.
A study published in the Journal of Psychopharmacology in May 2008 investigated the acceptability and usefulness of intrapulmonary THC administration using a vaporizer and pure THC instead of cannabis. Rising doses of THC (2, 4, 6 and 8 mg) were administered with 90 minutes intervals to twelve healthy males. Very low between-subject variability was observed in THC plasma concentrations, characterizing the vaporizer as a suitable method for the administration of THC.
In 2007 a study by University of California, San Francisco published in the Journal of the American Academy of Neurology examined the efficacy of a vaporizer that heats cannabis to a temperature between 180 °C (356 °F) and 200 °C (392 °F) degrees and found:
Using CO as an indicator, there was virtually no exposure to harmful combustion products using the vaporizing device. Since it replicates smoking's efficiency at producing the desired THC effect using smaller amounts of the active ingredient as opposed to pill forms, this device has great potential for improving the therapeutic utility of THC.
Our results show that a safe and effective cannabinoid delivery system seems to be available to patients. The final pulmonal uptake of THC is comparable to the smoking of cannabis, while avoiding the respiratory disadvantages of smoking.
When using plant material (crude flower tops), besides THC, several other cannabinoids and a range of other plant components including terpenoids were detected in the plant material. However, using pure THC in the vaporizer, no degradation products (D8-THC, CBN, or unknown compounds) were detected by HPLC analysis. Also, a substantially larger fraction of the THC was delivered to the vapor by using pure THC.
Analysis of the vapor from the vaporizer found that using multiple passes it delivered 36%–61% of the THC in the sample. A study using pure cannabinoid preparations achieved a maximum of 54%. Studies of cannabis cigarettes smoked via a smoking machine under varying conditions of puff duration and air speed found very similar efficiencies of 34% to 61%. Consequently, users can achieve the desired effect with a similar amount of material as when smoking.
In a 2001 study, researchers found that "it is possible to vaporize medically active THC by heating marijuana to a temperature short of the point of combustion, thereby eliminating or substantially reducing harmful smoke toxins that are normally present in marijuana smoke." The unit produced THC at a temperature of 185 °C (365 °F), while eliminating three measured combustion products, benzene, toluene and naphthalene. Carbon monoxide and smoke tars were also reduced, but not quantified.
A 1996 MAPS study tested two simple vaporizer models, a commercially-available electric hotplate vaporizer and a homemade hot air gun vaporizer, against water pipes and filtered and unfiltered cannabis cigarettes (joints). The smoke produced by each was analyzed for solid particulates (tars) and three major cannabinoids. The various ingestion methods were then rated based on their cannabinoid-to-tar ratio. The two tested vaporizers performed up to 25% better than unfiltered cannabis cigarettes (second cleanest) in terms of tar delivery. Both vaporizers produced more than ten times more tars than cannabinoids, though the NIDA-supplied marijuana used had a relatively low THC potency of 2.3%; the authors noted that using higher-quality marijuana or hash oil would have improved the cannabinoid/tar ratio. The same study found that water pipes (bongs) and filtered cigarettes performed 30% worse than regular, unfiltered joints. The reason was that waterpipes and filters filter out psychoactive THC with the tars, thereby requiring users to smoke more to reach their desired effect.
Vaporizers do not completely eliminate respiratory irritation. A large puff of potent, vaporized cannabis will often cause severe coughing. Vaporization systems that utilize water and/or ice for cooling and moisture conditioning by running the vapor through a water pipe or "vaporization water tool" with ice attempt to address the temperature and moisture factor of the delivered vapor to enable larger inhalations without the respiratory irritation that still results from dry-vapor delivery.
- Specimen density
- Weight, content of water and essential oils
- Consistency of material in the filling chamber
- Storage time of the vapor
- Inhalation method (breathing technique)
Not all those have been scientifically tested. Research using the vaporizer found the delivery efficiency highest at around 226 °C (439 °F), falling to about half efficiency at 150 °C (302 °F) to 180 °C (356 °F) degrees depending on material. The purest preparations produced the highest efficiencies, about 56% for pure THC versus 29% for plant material (female flower tops) with 12% THCA content. Besides THC, several other cannabinoids as well as a range of other plant components including terpenoids were detected in the plant material. Using pure THC in the vaporizer, no degradation products (delta-8-THC (D8-THC), cannabinol (CBN), or unknown compounds) were detected by HPLC analysis. The longer vapor is stored, the more THC is lost as it condenses on the surface of the vaporizer or the balloon. This loss may be negligible over a few minutes but may exceed 50% after 90 minutes. The Leiden University study found that as much as 30%–40% of inhaled THC was not absorbed by the lungs but simply exhaled. However, they did not find large individual differences in the amounts exhaled.
Vaporizers are sometimes used by chefs as a method of applying controlled heat to herbs and spices to release flavors that are otherwise difficult to titrate or apply, or that might be spoiled by overheating during cooking. Grant Achatz, chef-proprietor of Alinea in Chicago, "uses the aroma-filled bags as place-mats, punctured when plates are placed in front of the customer."
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