Geysering is caused by the rapid boiling of fuel in a fuel container.  The boiling causes the fuel to eject violently from the fuel tank opening when the cap is opened.    Conditions that can cause fuel to be in a geysering state include heat and elevation.   Using equipment for long periods of time in hot conditions or at higher elevations greatly increase the risk of fuel geysering.

The Soter Fueling Sytem™ DOES NOT prevent geysering, it simply provides a safer way to protect against it.

The Soter Fueling System™ provides a safer way to refuel chainsaws.  The Soter™ System uses an air-fluid exchange principle and provides a means for exchanging the air in the gas tank of your chainsaw with the fuel in your portable fuel container. When engaged, the Soter fuel tank receiver and probe (fuel tank cap) also allow pressure and hot fuel to be transferred from the fuel tank of your chainsaw into the Soter™ equipped portable fuel container and exchanged for fresh, cool fuel, thereby reducing pressure and temperature in the fuel tank of your chainsaw.

In field tests, the Soter Fueling System™ consistently filled chainsaws in 10–15 seconds. Once the chainsaw tank has reached maximum fuel level, the fuel stops flowing.