Vaporizer (inhalation device)
A vaporizer or vapouriser 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.
Vapor quality 
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 149.3 °C (300.7 °F), CBD 206.3 °C (403.3 °F), and CBN 212.7 °C (414.9 °F). and because most commercial vaporizers are slow in extraction and delivery, the vapor inhaled is first aromatic, but only minimally active; as the plant material temperature rises, the vapor becomes increasingly bio-active, but minimally aromatic, because most of the aromatics have already been released.
This problem is addressed in the modular vaporization tool-based systems by use of a sequential Venturi effect for more rapid extractions via a vaporization chamber bowl and vaporization heat wand or heat gun and is addressed in some box vaporizers by way of a Venturi-inducing extraction intake prior to the hose. With the vaporization chamber bowl approach, many common pipes can be modified, enabling the delivery of broader-spectrum vapor preferred by many users and higher in concentration, consistency, 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 prevents the attainment of fuller spectrum vapor, but are less convenient to use.
Scientific study 
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
- Variety and potency of cannabis used
- Different preparations such as crude flower tops, hashish, hash oil, etc.
- Storage time of the vapor
- Proportion of THC exhaled (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.
Culinary application 
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."
See also 
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