The Science Behind Vape Cartridge Failures with N.N. Analytics

#1 Failure: Leaks 

Oil leakage into the air inlet chamber is due to a mismatch in:  

• Cartridge Feed-Hole Diameter—the aperture of the feed hole is too large, allowing liquid to flood the cartridge-wicking material too quickly.  
• Wicking Material Porosity—porosity is too high (not dense enough), leading to liquid seeping through the wicking material and leaking out of the bottom of the cartridge.  
• Rheology of Liquid is Too Thin—the viscosity is too low, the elastic modulus is non-Newtonian, the shear rate is too low, or the tensile modulus is non-Newtonian or too high. 

#2 Failure: Clogs  

Lack of wicking material saturation is due to:  

• Cartridge Feed Hole Diameter—aperture is too small for liquid rheology.  
• Wicking Material Porosity—porosity is too high (too dense), leading to liquid not sufficiently saturating the wicking material, which presents as a dry hit.   
• Rheology of liquid being too thick—viscosity is too high, elastic modulus or tensile modulus is non-Newtonian, shear rate is too high.  

Cartridge Feed Hole Diameter  

• Feed holes too large or too many—flooding of the wicking material in the atomization chamber.  
• Feed holes too small or too few—poor saturation of the wicking material in the atomization chamber, leading to dry hits, which can be harmful. 

Coil-Wicking Material Selection

Ceramic  

• Ceramic particles can be emitted if the coils are not well washed/sintered before installation, leading to nano-particulates in the vapor stream.  
• Porosity (see below)  

Rayon  

• Density (see below)  

Cotton  

• Same issues as rayon wicking.  

Coil-Wicking Material Porosity/Density   

• Porosity is too high (not dense enough)—liquid flows too easily through and saturates the atomization chamber, leading to leaks through the 510-thread or clogs through the center post.   
• Porosity is too low (too dense)—liquid does not flow easily or saturate the atomization chamber, leading to dry-hits or the emission of harmful constituents due to elevated vaping temperatures.

510-Thread Inlet Air Hole Feed Size  

• Too large—leads to leakage related to improper rheology, making liquid too thin.  
• Too small—alters the ability to generate sufficient amounts of vapor, leading to dry hits, which can be harmful.  

Center Post Diameter

• Too small of a diameter leads to clogs from non-atomized liquid and a noticeable pressure drop.

Center Post Venturi-Effect Pressure Drop and Airflow  

• Buildup of excess liquid that was not vaporized in the center post, leading to clogs.   
• Rheology is too thin, leading to leaks.  

Cartridge Reservoir Size and Head-Pressure

• Too large—can lead to too much head pressure, flooding the wicking material in the atomization chamber, and is a major cause of leaks.  
• Too small—can lead to a lack of head pressure and dry hits due to a lack of liquid feed into the coil-wicking material in the atomization chamber.  

#4 Failure: Liquid-Based Issues 

• Batch-by-batch variation of oils—when distilled in different batches, the rheology of cannabis/hemp oils can vary greatly from previous batches.   
• Batch-by-batch variation of terpenoids and flavoring components—terpene products, especially in live resin formulations, can vary greatly.   
• Measurements and mixing during liquid product assembly—a single variation in standard operating procedures can disrupt the balance between liquid rheology and hardware. 

#5 Failure: Filling and Capping Parameters and Execution 

• Flooding of the Cartridge Coil—high fill temperature, unreasonably fast fill speed, or an improper fill angle leads to fast flooding without air gaps next to the coil-wicking material.  
• Insufficient Fill Volumes—overfilling of cartridges forces solution into the coil-wicking material before negative pressure is initiated by standard vaping conditions.  
• Clogging—poor saturation of the cartridge leads to capping failures from the application of caps without correct pressure leading to air gaps in the seal at the cap.