PTFE Membrane Vs PTFE Finish – Is There a Difference?

PTFE membrane on a baghouse filter under a microscope

Sí, hay una diferencia entre ambos. La membrana de PTFE se utiliza para aumentar la eficiencia de la recolección, mientras que la terminación PTFE se usa principalmente para proteger las bolsas de filtro contra ataques químicos.

What Are PTFE Membrane Filter Bags?

PTFE membrane on a baghouse filter under a microscope

PTFE membrane is a thin layer of PTFE laminated to the surface of a filter bag. It captures dust on the surface of the filter and easily releases the dust when pulsed.

PTFE membrane is semi-porous layer of PTFE bonded to the surface of a filter. This membrane acts at a permanent dustcake, capturing incoming dust particles (i.e. particulate matter or PM 2.5) on the surface of the filter (surface filtration) as opposed to normal filters that require a thick layer of dust buildup (dustcake) to actually reach peak efficiency. This means that PTFE membrane bags can operate at peak collection efficiency from the moment they are installed, and do not need to be precoated. Overtime, the membrane also works against the dust penetrating deep into the depth of the filter fabric, which is the cause of filter blinding. For this reason, PTFE membrane bags often last considerably longer than standard filter bags and have a more consistent differential pressure over time.

PTFE Baghouse filters with PTFE membrane have the highest collection efficiency of all filters in production today. Bags using membrane technology can collect particulate matter down to 2.5 microns in size at over 99.99% efficiency. (In laboratory testing one OEM’s PTFE filters had 0.00% detectable emissions in the test rig). For this reason, in the applications with very tight emissions requirements, PTFE membrane filters are the standard.

Membrane bags are not recommended for a few limited applications, usually involving oils and hydrocarbons are these can close off the pores of the membrane and cause the filter to plug up.

What Are Filter Bags with PTFE Finish or Treatment?

A Baghouse filter with PTFE (Teflon) Membrane

PTFE membrane or PTFE finish can be applied to a baghouse filter made from any fabric, such as fiberglass, polyester, or aramid (Nomex). It can even be used with filtros plisados o cartuchos.

In this use of PTFE, rather than creating a surface layer or membrane on top of the filter, the filter fabric is coated in a bath or spray of liquid polytetrafluoroethylene (PTFE) resin. This is done to protect the filter. The treatment improves the flex life, heat and chemical resistance and dust release from the fabric. This increases the service life and efficiency of the filters. PTFE finish is commonly used in applications with corrosive chemical compounds, sticky dusts, or high moisture contents.

Would you like to learn how PTFE membrane filter bags can improve your dust collector operation and save you money? Contact us today to find out more!

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¿Puedo reutilizar las jaulas al cambiar los filtros?

Bent and rusted dust collector filter cages

The answer is that it depends…In many applications it is possible to reuse the cages once or possibly more. But in many other applications it may not be wise to reuse the cages.

Damaged Baghouse Cages From Corrosion and Mishandling

The main two types of cage damage we see are physical damage (bending, breaking, warping, etc.) and corrosion. Cages frequently get bent or broken by maintenance personnel over time by handling during changeouts and maintenance work. Other times, cages are damaged when stacked on top of each other for storage.  Additionally, fires or temperature excursions can warp cages.

Rip in a baghouse filter caused by a broken support cageCorrosion can occur from chemical attacks (e.g. acid flashes,) or upset conditions within the system. In some applications, high moisture levels can promote corrosion of the metal cages very quickly. And sometimes cages are stored outside uncovered  and left exposed to the elements.

Reusing Damaged Cages Will Cause Your Baghouse Filters To Fail Sooner!

There are three ways damaged or corroded cages cause filters to fail:

A bent baghouse cage has worn holes in the filter.

Bent or warped cages can eventually wear holes through your bags and cause massive leaks.Using damaged or corroded cages along with new baghouse filters will damage your filters and lead them to fail. This means you will experience leaks or even total filter failure much quicker than normal. Such failures can have high costs in terms of maintenance, possible system shutdowns, lost production as well as the costs of buying replacement filters sooner than normal.

  • When pulsed bent cages can cause the filters to rub against each other or against the sides of the collector causing the bags to tear open
  • Bent, twisted, or broken cages will have many sharp edges that can cut holes in the fabric very quickly when pulsed
  • Rusted or corroded cages will eat through the bag fabric and very quickly cause holes to appear.

In applications with very corrosive environment
(acid/alkali compounds, high humidity, condensation, etc.) such as foundries, dryers, chemical processing, etc., it is essential to avoid reusing cages that are damaged or corroded.

Even in applications with milder environments, the frequent handling of cages during repeated changeouts will eventually result in damage to the cages. Using cages in good condition extends filter life and improves efficiency by preventing:

  • Tearing or cutting filter on sharp edges
  • Damage from abrasion from other bags or unit
  • Corrosion eating through the fabric on the bags (Consider investing in galvanized, epoxy-coated or stainless steel cages to improve resistance to corrosion
  • Ineffective cleaning by ensuring the bags are properly fitted to the cages (Bags need to fit correctly
    across entire cage in order to get the required snap back when pulsed with air…not possible with bent cages

Reusing Damaged Cages Can Cost You Dearly

Bent and rusted dust collector filter cages

Corroded (rusted) cages will lead to early bag failure. Avoid reusing cages if they are damaged or corroded in any way.

Even minor rips, holes, and tears in the bags can lead to exceeding emissions limits. In many plants, such a problem will cause an emissions spike, becoming a “reportable event”, with possible fines and sanctions from regulators as a consequence. Additionally, any baghouse malfunction has the potential for causing plant-wide problems, that may lead to shutdowns, production losses and other costs far in excess of replacing the cages.
You can avoid all these problems and more by not using damaged or corroded cages in your baghouse. Additionally, if you keep spare cages on site at your facility make sure to store them where they are protected from corrosion and avoid stacking to many rows on top of another to prevent bending.

Baghouse Filter Cage Styles

Do you have corroded or bent cages in your baghouse? Let us give you a quote today for new cages along with your next set of replacement filters and receive a discount on both! Contact us now for a free quote.

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