Technical info

PTFE tubes are made conductive by adding a small percentage of carbon. The amount used and the way it is introduced into the PTFE resin produces sufficient conductivity without contaminating or colouring the material. Most Unigasket tubes are available in conductive and non-conductive form. The conductive line is required when there is the possibility of electrostatic discharge. Most applications do not require conductive pipes, but in conditions where there is the accumulation of static electricity (usually produced by high speed), conductive pipes should be used to prevent hazards. This condition exists or is created when two different materials are in contact with each other and the electrons of one material are associated with the other by aligning themselves with it. If both materials are good conductors of electricity the electron flow will remain balanced. If one or both are insulators the flow will not occur, but a charge will build up in one of the materials (separation step). When this charge exceeds the dielectric strength of the material, a dielectric discharge occurs.
In the applications of PTFE pipes, considerations must be made on fluids and gases that are not very conductive and their flow velocity must also be considered. To be considered non-conductive of electricity, a liquid or gas must satisfy one or both of the following:
1. The fluid is not polar; there is an imbalance between protons and electrons.
2. The fluid contains an immiscible component or a suspended solid; i.e. kerosene water.
When a liquid of this kind is brought into a non-conductive PTFE tube, the separation phase occurs and an electric charge is accumulated. Accumulation becomes a function of the flow rate. When the resistance of the PTFE is exceeded, a sudden discharge occurs through the pipe wall. What occurs is an external discharge, through the pipe wall, to a ground point, usually the braid. The wall of the pipe is mechanically and thermally damaged leaving a hole of more or less small dimensions.
In the hydraulic field, high pressure often accompanies high speed. In many applications, fluids are filtered out of the system. Filter elements made of paper or glass fibers tend to charge the filtered fluids.
The petrochemical sector is very important. These are usually non-conductive, having an electrical resistance of 108 ohms. We are talking, for example, of petrol, white spirit, hydrazine, benzene, diesel oil, etc. Generally, these fluids are transferred at low speeds but there remains the possibility of an electrostatic discharge due to external environmental factors such as humidity and sometimes even temperature. These factors remain to be considered even in cases where the fluid speed is less than 1 meter per second.
NOTE: The information provided here does not cover all possible dangerous electrostatic discharge situations. In all applications where they are used: gasoline, steam or other fluids belonging to this category, it is recommended to contact Unigasket for a specific evaluation and advice. As a rule, all applications where non-conductive fluids are not used and for any of the conditions mentioned above, conductive inner tubes are recommended.