Overview
Endpoint testing — also called puff count testing or depletion testing — is the process of drawing standardized puffs from a vapor product until it no longer produces aerosol. The total number of puffs delivered before depletion is the product's puff count under those specific conditions.
This measurement matters for several reasons. For cannabis producers and vape brands, puff count is a direct consumer-facing claim. When a product label says "300 puffs," that number should be grounded in standardized, reproducible testing — not estimated from fill volume and a rough per-puff consumption rate. The UVM provides the instrument-generated data to back up that claim, or to reveal that it needs to be revised.
Puff count testing is also essential for quality control across production batches. If batch A delivers 280 puffs and batch B delivers 210 puffs under identical conditions, something changed — the fill volume, oil viscosity, wick material, or coil resistance. The UVM quantifies that variation so you can track it and respond before defective products ship.
For hardware comparison, puff count is one of the clearest performance differentiators. Two cartridges filled with the same oil, tested at the same power and puff profile, may deliver significantly different puff counts depending on wick design, coil geometry, and airflow. Running them side by side on the multi-channel UVM gives you a direct, objective comparison.
From a regulatory perspective, puff count data is becoming a requirement rather than an option. Canadian cannabis regulators expect standardized puff count information as part of product characterization. U.S. state regulators are moving in the same direction. Having instrument-generated, protocol-documented results puts manufacturers ahead of the compliance curve.
How It Works
The UVM uses infrared (IR) vapor density sensors positioned in the flow path downstream of the vapor product. On each puff, air is drawn through the product at a controlled flow rate and volume. If the product is producing aerosol, the IR sensor detects the suspended particles in the airstream and records a vapor density reading for that puff.
As the product depletes — oil level drops, the wick dries out, or the heating element can no longer vaporize liquid effectively — the vapor density reading on each puff begins to decline. Eventually, the reading drops below a user-defined threshold, indicating that the product is no longer producing meaningful aerosol output. At that point, the system flags the product as depleted and logs the total puff count.
The entire process runs unattended. Once configured and started, the UVM executes puffs at the defined interval until depletion is detected. An audible alarm signals completion so the operator can retrieve the product and export the data.
Setup Protocol
The following steps walk through a complete endpoint test from parameter definition to data export.
1. Define Puff Parameters
Set the puff volume, flow rate, and rest interval that define each standardized puff. For CORESTA-aligned protocols, a typical starting point is 55 mL puff volume at a flow rate that produces a 3-second puff duration, with a 30-second rest interval between puffs. These parameters can be adjusted to match specific regulatory protocols, mimic consumer behavior, or stress-test the product under aggressive conditions.
If using the UVM's integrated 510 power supply to fire the cartridge, set the target wattage and any preheat time. Preheat (typically 0.5 to 1 second before airflow begins) ensures the coil is at operating temperature when the puff starts, producing more consistent vapor density readings — especially on the first puff after a long rest.
2. Connect the Vapor Product
The connection method depends on the device type:
- 510-thread cartridges: Connect via the UVM's 510 power cable. This bypasses the consumer battery entirely, delivering precise, software-controlled wattage directly to the coil.
- Button-activated devices: Use the UVM's button pusher accessory, which physically actuates the device's fire button in sync with each puff.
- Puff-activated (draw-activated) devices: Connect via mouthpiece adapter. The airflow generated by the UVM's puff engine triggers the device's internal pressure or flow sensor, activating the heating element automatically.
3. Attach Inline Filter (Optional)
If you want to capture the emitted aerosol for gravimetric analysis or chemical profiling, attach an inline PTFE filter cartridge downstream of the vapor product. The filter captures particulate matter while allowing air to pass through. This step is optional for puff count testing alone, but allows you to combine endpoint detection with emissions capture in a single run.
4. Configure Endpoint Detection in Software
In the UVM control software, select the endpoint detection mode. Set the vapor density threshold — the minimum reading that counts as "vapor present." A typical threshold is 5-10% of the product's peak vapor density output. The software will terminate the test when consecutive puffs fall below this threshold, filtering out occasional low readings caused by air bubbles or momentary wick dry spots.
5. Start the Test
Press start. The system runs unattended, executing puffs at the defined interval. Depending on the product's fill volume, power level, and puff parameters, a full depletion test can take anywhere from two hours to over twelve hours. There is no operator intervention required during the run.
6. Completion and Data Retrieval
When the vapor density drops below the threshold for the configured number of consecutive puffs, the system stops puffing and sounds an audible alarm. The final puff count is displayed on screen. The full dataset — per-puff vapor density, timestamps, puff parameters, and final count — is available for export.
Interpreting Results
A typical depletion curve — vapor density plotted against puff number — follows a characteristic pattern. For most cartridge-style products, the vapor density starts high and remains relatively stable through the majority of the product's life. There is often a slight upward trend in the early puffs as the coil and wick reach thermal equilibrium, followed by a long plateau.
As the oil level drops and the wick begins to dry out, vapor density enters a gradual decline phase. The duration of this decline varies: some products transition sharply from full output to zero, while others taper off over dozens of puffs. Finally, there is a sharp dropoff where the product is essentially depleted and the readings fall to near zero.
Several factors influence the total puff count and the shape of the depletion curve:
- Power level: Higher wattage vaporizes more oil per puff, reducing total puff count but often increasing per-puff vapor density.
- Puff volume: Larger puff volumes draw more air through the product per puff. Depending on the product's design, this may increase oil consumption per puff and reduce total count.
- Puff speed (flow rate): Higher flow rates can affect wicking behavior and coil temperature, influencing both vapor density and total puff count.
- Oil viscosity: Thicker oils wick more slowly. At aggressive puff rates, a viscous oil may produce intermittent dry hits and an irregular depletion curve, even if the cartridge is not truly depleted.
- Wick design: Ceramic wicks, cotton wicks, and mesh coils all have different wicking rates and thermal characteristics. These directly affect how evenly the product depletes and how sharply the endpoint occurs.
Understanding these factors is essential for interpreting puff count data correctly. A product that delivers 300 puffs at 3.0W and 55 mL may deliver only 200 puffs at 4.0W and 70 mL. The puff count is not an intrinsic property of the product — it is a function of the product and the test conditions together. This is why standardized, documented puff parameters are critical for any puff count claim.
Multi-Channel Comparison
The 4-channel UVM runs up to four products simultaneously under identical puff conditions — same volume, flow rate, rest interval, and power level on every channel. This capability transforms puff count testing from a single-product measurement into a comparative or statistical tool.
For batch QC, load four units from the same production batch and run them to depletion. The resulting four puff counts — along with per-puff vapor density profiles — give you a measure of batch consistency. Tight clustering indicates a well-controlled manufacturing process. Wide spread indicates variability in fill volume, coil resistance, or wick quality that warrants investigation.
For head-to-head product comparison, load four different products — different cartridge hardware, different formulations, or different brands — and test them under the same conditions. The data directly answers questions like: which cartridge delivers the most puffs with our oil? Which formulation depletes more evenly? Which hardware produces the most consistent vapor output from first puff to last?
Because all four channels share the same puff engine timing, the test conditions are genuinely identical — not "similar" or "approximately matched," but synchronized to the same puff clock. This eliminates a common source of inter-test variability and makes the comparison data defensible.
Data Output
The UVM logs a complete record for every puff in the test. The exported dataset includes:
- Puff number: Sequential count from the first puff to the last.
- Vapor density reading: The IR sensor measurement for each puff, providing a relative measure of aerosol output.
- Timestamp: The exact time each puff was executed, allowing calculation of actual rest intervals and total test duration.
- Puff parameters: Volume, flow rate, duration, and power level as configured for the test.
- Final puff count: The total number of puffs delivered before the endpoint threshold was reached.
Data is exported as Excel (.xlsx) or CSV files, ready for import into statistical software, LIMS systems, or internal QC databases. For multi-channel tests, data from all channels is exported in a single file with channel identifiers, enabling direct comparison in a spreadsheet or charting tool.