A vaporizer is a technological marvel. The introduction of vaporizers into the cannabis sector precipitated a change in the way that we use cannabis.
Since time immemorial, cannabis was smoked. It wasn’t until we understood the biological consequences of smoking that we began postulating alternative ways to ingest cannabis.
As the saying goes, necessity is the mother of invention, and the invention of the vaporizer was borne out of our need for alternative modes of ingestion other than smoking. Initially, this pertained to tobacco products, but now that society is more permissive, it applies to cannabis as well.
Cannabis presented unique challenges to the design of the vaporizer. The function of the vaporizer needed to accommodate consumer demand for dry herb or cannabis flower, tinctures, waxes, butters, resin, kief, hashish, and oils.
The point at which cannabis flower, and extracts, vaporize and decarboxylate varies. They have different densities and physical properties that require certain conditions to achieve decarboxylation and the enthalpy of vaporization.
Consequently, manufacturers of vaporizers needed to innovate their products well beyond what was introduced to the consumer market years ago.
What we see today is a mastery of applied science.
Vaporizers leverage basic principles of thermodynamics and electromagnetism. Particularly, the transference of thermal energy and the flow of electricity within a circuit.
The application of these scientific principles in vaporizer technology are perhaps best exemplified in the context, and discussion, of a sub-ohm vaporizer.
Before we can discuss how the properties of electromagnetism and thermodynamics operate within a vaporizer, it is imperative that we understand what they are, and how they operate in theory.
Don’t worry, this isn’t a science lesson.
Voltage, Amperage, Wattage, and Ohm’s
What voltage, amperage, wattage, and ohm’s all have in common is that they are units of measurement. We use these units of measurement to quantify electric pressure, electric current, energy conversion, and electrical resistance, respectively.
Moreover, the terms voltage, amperage, wattage, and ohms are used to help us understand and describe what is occurring within an electrical circuit.
Understanding what is occurring within an electrical circuit is rather simple. Hereafter, we will be explaining how voltage, amperage, wattage, and ohms relate to one another by way of analogy.
Think of a garden hose with two ends, with one end attached to a running faucet, while the other is unencumbered. Water is freely flowing from the faucet, through the hose, and into the garden bed.
The faucet is the source of the water, and responsible for the flow of water through the hose. As the water flows through the hose, it exerts pressure on the hose itself, until reaching the open-end and spilling water on to the dirt.
In this analogy, the faucet would represent a battery, insofar as it is the source for water in the hose in the same way that a battery would be the source of electricity in a circuit.
The volume of water that flows through the hose represents electric current (amperage), while the resultant pressure exerted by the water on the hose is representative of electric pressure (voltage).
As water spills from the hose it undergoes an energy transfer which dissipates into the garden. In the context of electricity, this energy transfer (wattage) can be used to power anything that is plugged into the circuit.
To further clarify how voltage, amperage, wattage, and ohms relate to one another, here is the formulaic expression of what we discussed previously.
We determine electric current (amps) in a circuit by dividing the electric pressure (volts) by the electrical resistance (ohm’s) of the circuit.
I (amps) = V (volts) / R (ohms)
We determine the energy transfer (watts) by multiplying the electric pressure (volts) by the electric current (amps).
W (watts) = V (volts) * I (amps)
Electrical Resistance (Ohm’s)
You may be wondering, what about electrical resistance? Well, the problem is that electrical resistance cannot be adequately represented in the analogy. This is because electrical resistance is inversely proportional to electric current. Think opposite. If one increases the other decreases, if one decreases the other increases. This type of relationship cannot be expressed in our garden hose analogy.
This is unfortunate because the concept of electrical resistance is elemental if you are to understand what is occurring within an electric circuit, and by extension, a vaporizer.
A resistor is an electrical component of a circuit that impedes the flow of electricity by releasing some of its energy in the form of heat.
In a vaporizer, the resistor in the circuit is the atomizer or heating coil.
Now that we understand how the forces of electromagnetism operate in theory, we are able to discuss how they operate within standard vaporizers and vape mods that are used for “sub-ohming” or “cloud-chasing”.
The circuitry within a typical vaporizer consists of a battery, conductive wire, a switch (that either connects or disconnects the circuit) and a resistor in the form of an atomizer or heating coil. When a vaporizer is turned on, the switch is engaged, meaning the circuit is complete and electricity can travel freely.
As the electricity passes through the resistor (atomizer), some of the energy is released in the form of heat (energy conversion). This released energy is measured in watts and determines the output power of the vape device.
The heat generated by the atomizer is used to vaporize your product.
The circuitry within a sub-ohm vaporizer is comprised of the same components as a typical vaporizer, albeit with one exception. The resistor (atomizer) has an electrical resistance that is less than one ohm.
The significance of having an atomizer with an electrical resistance that is less than one ohm is that it increases the electric current (amperage). If we remember our analogy, this means that the volume of water flowing through the hose has increased.
The consequence of increased amperage is that the wattage proportionally increases. We know from our understanding of how a vaporizer works that an increase in watts means an increase in the heat released by the atomizer or heating coil.
You may be wondering, what is the point of manipulating ohms, wouldn’t increasing voltage have the same result? The answer is yes, increasing the voltage would have the same result, but it would also require a larger, more powerful, battery. Decreasing electrical resistance is the only way to increase the wattage in a device with a fixed voltage.
This is why manufacturers will offer after-market modifications for existing vape devices that allows people to “sub-ohm” or “cloud chase” without having to purchase a more powerful device.
Transference of Thermal Energy
The transference of energy as heat occurs in three processes, conduction, convection, and electromagnetic radiation. For the purposes of this post, we will only be focusing on conduction and convection as they pertain to the function of a vaporizer.
In conductive transference of energy, molecules, atoms, and electrons collide with one another. Think of a spoon with one end resting in a hot pan on the stove. Over time, and if the pan is kept at consistent heat, the spoon will reach the same temperature as the pan. This is because the hot pan transfers its kinetic energy to the spoon.
In convective transference of energy, the substance that contains the thermal energy is in motion. Think of a pot of water on a hot stove. As water at the bottom of the pot increases in temperature it rises to the top of the pot.
In so doing, colder water takes its place and settles to the bottom of the pot. This circulation of water is due to the difference in density between the cooler and warmer water. Together they form a current. This process is representative of the convective transference of energy.
Thermodynamic Processes in a Vaporizer
In a vaporizer, heat is applied to your product through convection, conduction, or a combination of both. The important distinction here is that the application of heat is not necessarily consistent with the process by which your product is vaporized.
The role of thermal conduction in a vaporizer is very simple, the atomizer gets hot and transfers its kinetic energy to your product. However, the amount of thermal energy required for the enthalpy of vaporization is contentious.
Particularly when the product is cannabis flower. This is because the compounds within cannabis flower will vaporize at a different temperature than the plant matter itself. This means that you cannot be sure if your cannabis is being wholly vaporized, or if it is partially vaporized and partially combusted.
While it is theoretically possible for a solid to change its state of matter to a gas, the likelihood that your “dry herb vaporizer” is sublimating your cannabis flower is unlikely. Manufacturers will often circumvent this point by saying that the vaporization is sufficient enough for the cannabinoid compounds, but not sufficient to vaporize or burn the plant matter itself.
On this point I will say that from my own experience in using a “dry herb vaporizer”, that the residue in the chamber after vaping appeared singed and dried out. I was using the Pax 3 Dry Herb Vaporizer.
The salient point remains, conduction heating poses an increased risk for burning, especially when vaping cannabis flower.
The role of thermal convection in a vaporizer is slightly more confusing. Again, there is an ambiguity as to what role thermal convection plays in the vaporization process.
If we are dealing with strictly liquid or viscous extracts, then thermal convection would be the process by which those substances internal temperature increased and changed their state of matter from a liquid to a gas.
However, if we are referring to a “dry herb vaporizer”, the role of thermal convection changes entirely. As stated previously, thermal convection requires that the substance with thermal energy be in motion. Think of our example of a pot of water on a hot stove.
The buoyancy forces at work in the pot create a current that distributes heat from an area of high concentration to an area of low concentration. This cannot take place in a solid. So, how is thermal convection taking place in a dry herb vaporizer?
The answer is, through the passage of hot air through the device. This is what I mean when I say that the application of heat is not always consistent with the process of vaporization. A “dry herb vaporizer” is basically a tiny oven that is baking or roasting your cannabis.
Thermodynamics in a Sub-Ohm Vaporizer
The purpose of sub-ohm mods is to increase the temperature output of a vaporizer beyond the limitations of its fixed-voltage battery. This is because vaping at higher temperatures creates bigger vapor clouds.
This is usually achieved with e-liquid mixtures due to the fact that users can adjust the amount of propylene glycol or vegetable glycerin for max effect, but also because liquids or viscous mixtures heat more consistently and allow for greater measure of control.