Typical pumping loop . π www . valve-world . net Valve World June 2024
Recent regulations in the US and Europe address Per and Polyfluoro Alkyl Substances
( PFAS ). While some PFAS pose health risks , safe options like fluoropolymers and elastomers are crucial in various sealing devices . This paper discusses their significance and potential industrial implications amidst evolving regulations .
By Phil Mahoney , Director of Engineering Services , Stationary Equipment , A . W . Chesterton , and Fluid Sealing Association , Chair of Government Affairs and PFAS Task
Force ; and Michael Wachinger , Senior Regional Manager ANZ / SEA ,
A . W . Chesterton Company
PFAS stands for Per and Poly FluoroAlkyl Substances . There are many contradictory definitions for this ; however , the most common in use is “ a synthetic chemical compound group with at least one fully fluorinated carbon atom .” Depending on the definition , the number of chemicals under the PFAS umbrella can be between 4,700 and 10,000 + chemicals . According to some industry experts , 10 % of those are in commercial products internationally in various forms . The carbon-fluorine bond used in PFAS is one of the strongest in chemistry , resulting in incredibly useful and unique properties . This molecular structure also means they do not readily break down in nature ; hence , the term sometimes used is “ forever chemicals ”. There are two categories of PFAS material : non-polymers and polymers . Non-polymer PFAS generally fall into two classes :
• Per : Fluorine atoms are replacing all hydrogen atoms that are linked to all carbon atoms in a chain ( other than those associated with a functional group ).
• Poly : Fluorine atoms are replacing all hydrogen atoms linked to at least one carbon atom in a chain ( other than those associated with a functional group ).
Sealing
PFAS : why are they critical to sealing devices ?
PFAS risk
Extensive research has identified potential health risks from long-term exposure to certain nonpolymeric PFAS materials , such as PFOS and PFOA , currently categorised as persistent organic pollutants ( POPs ) in the EU . These substances have been detected in various environmental sources . However , further investigation is required to establish exposure ’ s precise causes and effects and differentiate hazardous from non-hazardous PFAS materials . PFOA has not been commercially utilised by major producers for nearly a decade in the USA . PFOS is commonly found in firefighting foams , but it is not a typical component in USA-manufactured sealing devices . Note that not ALL PFAS are considered hazardous . Polytetrafluoroethylene ( PTFE ) and fluoroelastomers fall within the polymer category of PFAS , characterised by their high molecular weight , non-bioavailability , and non-toxic nature . They
Polymers classed as Fluoropolymers have fluorines attached directly to the carbon-only backbone , Perfluoropolyether have additional oxygen atoms , and side-chain fluorinated polymers have a variety of fluorinated side chains .
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