Expansion Tank – What is it in Vaping?

Definition

An Expansion Tank is a small reservoir or overflow chamber built into—or added onto—an e-cigarette atomiser or clearomiser. Its sole purpose is to catch excess e-liquid that expands when heated or displaced by coilflooding, preventing e-juice from leaking out of airflow slots or into the battery connection. In simple terms, it acts like an insurance policy against messy leaks while keeping your vape and pockets clean.

Technical Details

How It Works

The tank sits directly beneath the coil deck, separated by a one-way silicone membrane or micro-channel. When coil temperature rises, e-liquid viscosity drops and volume increases by up to 4 %. The membrane flexes, allowing surplus e-juice to flow into the sealed expansion chamber. Once the device cools, negative pressure draws the liquid back toward the wick, ready for re-vaporisation.

Specifications & Variations

• Capacity: 0.5–2.0 mL depending on atomiser size.
• Materials: Food-grade PCTG, SS316L, or borosilicate glass.
• Threading: 510-compatible or integrated into eGo style clearomisers.
• Types: Fixed (factory-built) vs. modular (screw-on “bubble” sections).

Usage & Tips

• Priming: After filling, take three dry pulls (no power) to equalise pressure and move any overflow into the expansion tank.
• Cleaning: Rinse with warm water weekly; avoid alcohol on silicone seals.
• Problem:Gurgling? Remove the mouthpiece and flick the device downward over a tissue to empty the chamber.
• Safety: Never over-tighten; cracked expansion tanks can leak nicotine-containing e-liquid onto skin.

History & Context

First seen on 2013 E-Shisha pens to counteract thin e-juice and high-temperature coils, expansion tanks became mainstream when sub-ohmvaping took off. Today, most premium sub-ohm tanks and rebuildable atomisers include them as standard, reducing returns due to leaking by up to 40 % according to Australian vape retailers.