Wikipedia
PharMed is a polypropylene-based material combined with a plasticizer which is opaque beige in color. It remains flexible and stable at temperatures between -30 and 135 °C, and meets the requirements of the U.S. Food and Drug Administration (FDA) food quality United States Pharmacopeia class VI (the most stringent class). It has low gas permeability, can withstand repeated sterilization in an autoclave, and is considered to have a long service life (much higher than an otherwise comparable material, silicone). It is frequently used in medical/ pharmaceutical applications (particularly peristaltic pumps), hence its name. It is manufactured by Saint-Gobain Performance Plastics of Akron, Ohio which also manufactures Tygon tubing. Its Bates number is 521536942.
PharMed tubing is considered suitable for water analysis as it will not contaminate samples. It is also considered to be biocompatible, though it is not intended for use as a medical implant material.