PTFE hoses are widely used to transport gases like Oxygen, Argon, Hydrogen, Air, Nitrogen oxides, Carbon oxides, etc. Thus, these hoses can be used in various applications, such as welding, cryogenic cooling, and gas bottle filling.
A low permeation is a key design parameter for these hoses; this parameter indicates how many gas molecules can pass through the wall of the hose. If these molecules escape from inside the hose to the external environment, related consequences can be higher costs or hazards such as explosions or threats to life. If there is an ingress into the hose from outside, then contamination can occur; for example, water or oxygen ingress can cause bad welding joints, corrosion of other parts in the system or false readings in measurement equipment.
Some other fluoropolymers are less permeable then PTFE, but their max operating temperatures are much lower, and these polymers are more expensive or less flexible. Flexible steel hoses are almost zero permeable and offer higher temperature resistance than PTFE, but PTFE hoses show superior flex fatigue resistance, are non-corrosive and light weight. Additionally, the smooth bore of PTFE hoses induces lower, or even zero, turbulent flow of the gases—avoiding high pressure drops. Against rubber, PTFE shows significantly lower permeability.
By a secondary process of post sintering, the permeability of the PTFE liner can be decreased even further, making PTFE the ideal solution.