What is PTFE?

We are often asked "just what is PTFE". PTFE is a product we are all familiar with, just not by that name. PTFE stands for PolyTetraFluoroEthylene, which is the chemical termfor the polymer (CF2)n.Polytetrafluoroethylene (PTFE), (DuPont's trademark of Teflon®) is a thermoplastic member of the fluoropolymer family of plastics. PTFE has a low coefficient of friction (it is very slick) ,has excellent insulating properties, and is chemically inert to most chemicals. It also can withstand high heat (to 500 F) applications and it is well known for its anti-stick properties.

PTFE Packing

PTFE Packing alone as a term refers to Gasketing, braided packing, even an o-ring. A packing is simply a product that is used to block the path of a leak. So when someone asks for PTFE packing our first question is "what type". Most commonly the term has become an abbreviation for PTFE Pump or valve packing.

The next question is "is this for food or potable water"… Does it need to meet FDA specifications? The reason is most PTFE packings have some sort of lubrication added to them to help prevent them from burning up on pump start up. PTFE packings are particularly vulnerable to friction on startup because they expand from heat (including heat generated by friction) at a greater rate than metal. As a result, if the packing does not break in properly (or was over tightened) it will not seal properly, and will not last. The lubrication used on most braided packing's is generally mineral oil (because it's cheap). If your packing is going to be FDA approved a food grade silicone lubricant is used in place of the mineral oil.

How is it braided?

The method of braiding will define how soft a packing feels. A looser braid like a square braid will make the packing better suited to radially expand under compression, making it a better choice for older, worn pumps. An interlaced braid is much tighter, making the packing denser with fewer leak paths through the braid. These denser packing's will seal higher pressures so they work well in new pumps and valves. We also offer various hard and expanded (soft) PTFE yarn versions.

PTFE packing is utilized in a really broad range of applications. Often, customers simply request PTFE packing. In which case our general service Ameri-Tef (style 620) will be supplied http://www.aspseal.com/ameri-tef.html . As long as the customer is not using it for FDA required applications it will likely do an excellent job.

PTFE is often combined with other materials such as graphite, to improve the lubricity and minimize the cold flow often associated with PTFE product. Our Ameri-lon packing is an excellent example of this.

Ameri-lon has superior resistance to abrasive service applications. It has become a favorite style with waste water treatment facilities for it's resistance to abrasion. PTFE is also often combined with Kevlar, for reciprocating pump applications, copper wire, to act as a scrapper while it seals in polish rod applications, and other materials http://www.aspseal.com/pumppacking.html (linzing, nomex, novaloid, etc.). For Mixer application internal rubber cords or a core of rubber are added to give the packing recovery from high run-out mixer applications. There are many different types of braided packing available in the market. The staff at American Seal & Packing will be happy to assist you with a recommendation.

Of course not all applications require a PTFE based braided packing. Vee Packing is an excellent way to seal Valves and reciprocating pumps in low to high pressure applications.

Gaskets of all shapes and sizes can be made of PTFE or PTFE based materials. Our Ameri-lon gasket materials are engineered to overcome the issues of cold flow and inconsistent tensile strength. Made with Dupont's HS10 process the Ameri-lon line is not made by skiving billets as most manufacturers do. The reason is this process causes a high tensile strength in one direction but not in the other. Our Ameri-lon has an even tensile strength. Combine that with barium Sulfate, Silica or glass sphere filler and you have a problem solving gasket material.

Expanded PTFE (EPTFE) is available in sheet, cut gaskets and rolls of Joint sealant. All excellent choices when a soft clean gasket is required. Each version has the normal 0-14 ph and wide temperature range (-450 F to +500 F) range but joint sealant is an effective way to cut waste, and make installation easy with the adhesive backing, peel and stick.

PTFE is known for its ability to reduce friction. It provides better lifetime value, return on investment and durability. PTFE is slippery which allows it to reduce friction to minimum. The tendency of PTFE makes it an energy efficient choice for industries to save power consumption in pumps and also keep heat generation under control when in operation.

The biggest advantage of using PTFE is that it has an exceptionally high resistance to chemical components. They can easily withstand even when continuously exposed to highly aggressive fluids. Users can use them conveniently in scenarios which involves, acids, and bases without the fear of breaking the seal. They can also be used with items like concentrated sulfuric acid, nitric and chlorine dioxide. When there is a requirement to transfer content that includes such acids, obviously PTFE packing is the best fit for the scenario which will ensure prompt delivery.

Regardless of your application, if you have a need for PTFE, American Seal & Packing has a solution for you.

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