Conventionally lined Teflon (PTFE) valves in DuPont Dow Elastomers' Pontchartrain plant, La Place, La., were prone to failure when 18°C liquid chloroprene permeated the Teflon lining and made it swell. But new butterfly valves made with Teflon NXT resist absorption of chloroprene and a whole host of other caustic chemicals and extend valve service life by nearly eightfold.
Teflon NXT is said to have higher creep resistance and stiffness than conventional PTFE as well as a smoother surface. In addition, the inherent lubricity of the NXT material lets the valve operate smoothly unlike metal valves which often see their lubricants washed away by chloroprene and other harsh fluids.
Information for this article was provided by DuPont Fluoroproducts, Wilmington, Del.
|Typical properties for Teflon NXT and conventional PTFE|
|Tensile strength, (psi)|
|Elongation at break, %|
|DEFORMATION UNDER LOAD (CREEP), 73°F, %|
|Comparative permeation rates for Teflon NXT versus conventional PTFE|