PTFE (polytetrafluoroethylene) is a problem solver. When the application parameters are outside the limits allowed by other types of pipes, Unigasket with its PTFE pipes offers the right solution. The chemical compatibility of PTFE, combined with its unique physical characteristics, makes it the most suitable plastic material for the most diverse applications.
The benefits are to be considered;
1. Resistant and flexible: reinforced with steel braids, the PTFE Unigasket tubes can work in conditions where high pressures, continuous bending and vibrations make this type of application a particular challenge. Properly applied and installed, braided PTFE hoses can withstand hundreds of thousands of cycles without fatigue or breakage.
2. Inertia and chemical resistance: Unigasket PTFE pipes are able to handle an infinite variety of fluids at external pressures and temperatures. They are the best-known tubes in the world.
3. Wide temperature range: PTFE hoses can withstand temperatures from -70 ° C to 260 ° C in all kinds of conditions and can be handled safely even in cold water / steam cycles.
4. Non-stick and low friction: almost no substance can adhere to the PTFE. This property ensures the purity of any fluid that is transferred with these types of tubes. It also allows reuse and alternate use for different fluids. With a coefficient of friction of 0.05 there can be no deposits and the flow rates are high during the life of the hose.
5. Resistance to humidity: PTFE is naturally not familiar to humidity. In fact, absorption is less than 0.01%. No smell, flavour or colour passes to the fluids transferred from the PTFE, making it an approved material for contact with food under FDA and EC regulations.
Effusion or permeation is the process of migration of one substance into another, usually the movement of a gas through a tube material. Permeation is specific to the substance, temperature, pressure and permeation material. (See also question 8).
The effusion can take place with different types of material and with different types of pipe material. In any case, some questions must be asked:
1. What is the degree of effusion? Is it constant or intermittent?
2. How dangerous is the transported material? Is it harmful? Is it toxic? Is it flammable? Is it explosive? It is corrosive
3. What is the external environmental condition? Will the product be exposed to the sun? In the open air? To an enclosed space? Near a heat source or ignition? Near a source of drinking water or where it can create other health risks?
The wall thickness can vary some properties of the tube, for example it can increase the radius of curvature, reduce flexibility and increase the strength of the rim. As it should already be known, the thickness of the wall does not change the permeation rate or the effusive characteristics of the PTFE. Permeation is a function related to the porosity of PTFE which does not essentially vary with changes in thickness, characteristics of the material being transferred, pressure or other related factors.
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.
An application for Unigasket PTFE pipes can be found in almost all industries: from aggressive chemical transfers, to high food purity, to pharmaceutical processes; from aerospace and automotive to petrochemical processes .. Here are some of the benefits: 1. Reduction of maintenance costs: The life of Unigasket PTFE hoses is much longer than rubber or elastomer hoses. 2. Less production loss: The real cost of a failed tube is often loss of production or product deterioration. The properties of Unigasket PTFE tubes make the assembly more durable than other types of tubes. 3. Large margin of safety: Unigasket PTFE hoses can safely handle even the most dangerous fluids vapors, acids, caustics, harmful gases and even flammable liquids. Built with safety features, they have been designed not only for the application but also for the operator.
The taped corrugated tubes are produced through the progressive overlapping of spiralled and sintered material one after the other helically. The result is a very flexible PTFE tube that can be produced with very large lengths and diameters (up to 4”).
Unigasket is one of the few companies in the world to produce it. For specifics, see the products section or contact the Unigasket sales office.
It is best to classify applications based on the answers to the previous questions. There are usually categories in this regard and they are: 1. Materials that are not corrosive or noxious but can transfer to healthy air in an enclosed space and therefore cause danger to personnel.
2. Materials that turn into vapor if a certain temperature is reached, i.e. fluids boiling at 52 ° C at atmospheric pressure. Some substances can form chemicals with exposure to air. These chemicals can be corrosive and / or cause damage to personnel or in any case create danger. For example, liquid chlorine can spread as a gas and form hydrochloric acid in the atmosphere.
3. Corrosive, noxious or dangerous materials, which are already gases at atmospheric pressure and room temperature, known for effusion through PTFE