To prevent oxygen from entering the carbon black synthesis system and the leakage of inert gases, centering insulators are used in the electrode input chamber – insulators of the input chamber.

Insulators of the input chamber are made of the following materials:
- ebonite-material of manufacture (for FSM-500 and FSM-500 VS installations);
- caprolon or fluoroplast (suitable for the entire line of installations);
- copper-is installed only on current collectors of the sample of 2013.

Ebonite insulators have the lowest expansion limit of the material, which allows them to be used at peak temperatures, without compromising the movement of the electrode.
Nylon and fluoroplast insulators are cheaper, but less resistant to high temperatures. At the time of strong heating of the input chamber, insulators of this type can stop the movement of the electrode into the combustion chamber, which will lead to a slowdown in the process of carbon black synthesis. According to the regulations for the operation of equipment of the FSM line, when using nylon or fluoroplast insulators, the electrode insertion chamber must be inspected at least 1 time every 2 weeks.