Refill Port – What is it in Vaping?

Refill Port – Definition

A refill port is the small, sealed opening on a refillablevapetank, pod or RDTA that allows e-liquid to be added without removing or disassembling the device. It is usually covered by a rubber or silicone flap or threaded cap to prevent leaks and maintain internal pressure. Its sole purpose is to make topping up e-liquid quick, clean and convenient for Australian vapers, whether they are using a beginner pod kit or an advanced RTA.

Technical Details

Most refill ports use a self-sealing silicone membrane or spring-loaded valve that opens when the nozzle of an e-liquid bottle is inserted and snaps shut when it is removed. Standard bottle tip diameters range from 2 mm to 6 mm, while larger “unicorn” or “chubby gorilla” bottles may need a 10–12 mm port. Ports are positioned either on the top (top-fill RTAs and sub-ohm tanks) or on the side/bottom (older RDTA designs). Variations include:

• Sliding top cap: A metal sleeve slides back to expose the port.
• Threaded cap: A knurled screw-off top revealing a kidney-shaped port.
• Silicone plug: A soft flap that lifts up; common in pods and MTL tanks.

All types are designed to handle up to 50 W of internal pressure without leaking when used correctly.

Usage & Tips

Always close airflow slots before opening the refill port to minimise vacuum loss and prevent gurgling. Insert the bottle nozzle gently at a slight angle to avoid damaging the silicone seal. If e-liquid seeps out, check for:

• Trapped air bubbles—tapping the tank lightly or inverting it can release them.
• Worn or torn silicone—replace the seal or the entire pod.
• Overfilling—leave 1–2 mm of air above the port to allow for expansion in hot Australian climates.

Keep the refill port clean by wiping it with a tissue after every refill; residual juice can attract dust and affect resistance readings on rebuildable atomisers.

History & Context

The refill port evolved from the open drip wells of early RDAs. As vapers sought longer sessions without dripping, manufacturers added sealed filling holes to RTAs in 2014. The modern top-fill port, with its slide or twist mechanism, became mainstream by 2017 and is now standard on almost every refillable device sold in Australia.