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Green Industry and The Environment


…or plug in a Purex

The recirculating industrial fume extractor

Why use a recirculating fume extractor?

External venting systems, or vent to atmosphere extraction systems that pump dust and fumes outside, polluting the environment. The alternative is a Purex Recirculating Filter System. The Purex extractor captures dust and fumes in specialized filters and returns clean, purified air to the workplace.

Purex - The better alternative to pumping fumes outside

The Purex extractor is simply connected next to the process. If the process moves, the extractor easily moves with it.


Comparison table:



Venting to the Environment System

Recirculation System (Purex)

How long will the system take to install?

Several days on average.

In many cases just minutes.

Will there be any disruption in the workplace?

Expensive contractors and scaffold etc. may be required, disrupting work for lengthy periods.

Minor if any.

Can the system be moved?

Only by contractors with scaffold etc. meaning extra cost and disruption to work.

Yes. Simply unplug, move to new location and reconnect.

Are holes in the building required?

Yes. They need to be specially cut and sealed.


Are external emissions regulations a problem?

Company must investigate and obey local laws.

Not applicable. No problem.

Is there any energy lost e.g. heating/conditioning costs?

Energy and therefore money is wasted when heated or conditioned air is pumped outside.

No energy or heat is lost as the air is recycled.

Are there any ducting / installation costs?

Expensive - as ducting needs to be purchased and specialist installation is required.

Minimal if any, depending on process.

Are there any cleaning costs?

Specialist cleaning required to prevent risk of fire or contamination in ductwork. Again contractors, scaffold, disruption and expense.

Minimal if any.

Are there any decontamination costs?

Specialist decontamination may be required should the ducting be removed.


Can fumes be drawn back into the workplace?

Yes. Through windows or vents.

Not possible as all fumes are locked into filters.

Could there be disputes with my neighbors?

Yes. Over hazardous fumes and odors.

Not applicable. No problem.

Could temperature control of machinery (i.e. reflow oven) be affected?

Yes, fluctuations in extraction rates can be caused by external weather conditions making temperature control more difficult.


Flow control provides the correct maintainable extraction rate and temperature, reducing reject rates

Is planning permission required to install the extraction system?

Expensive, time consuming planning permission may be required.


Could the roof leak?

Possible if not sealed and installed correctly.

Not applicable. No problem.

Can negate buildings/roofing insurance


Not applicable. No problem.

May not be allowed by landlord


Not applicable. No problem.

Why choose Purex?

Purex International have years of operational knowledge pooled together between staff members, all of which is available to the customer. Qualified engineers are on hand to survey your site and put together the best solution for your individual application.


Modular design

Different applications produce different types and amounts of particulates and gases so a variety of filters and extractors is required. Purex provide the correct combination of components to be implemented to do the job correctly. These can include:

  • Cabinets and coatings
  • Blower
  • Reverse Airflow
  • Pre-filters
  • HEPA filters

Reverse airflow

As soon as air is drawn into a Purex machine, its direction of flow is diverted through 90 degrees. This throws larger particles out of the air stream and into a collection tray or pre-filter bag, thus preventing them from entering the main filter and prematurely reducing its life span.

The Reverse Airflow system has an added benefit. When vapor is present in the extract air (e.g. from lasing PVC) it will condense into a liquid inside the filters and drip downwards. In other top loading fume extractors this liquid could potentially drip onto any electrics and motors below to cause a hazard. In Purex systems any liquid is collected in a tray or absorbent pad.



Inexpensive pre-filters are used to collect larger particles over 1-3 microns to prevent them from prematurely blocking the main filters.


Several options are available for processes that produce large quantities of dust; high capacity pre-filters, various types of bag filter and Cascade boxes.

Main HEPA (High Efficiency Particle Air) filters

The filters used in Purex fume extractors have been designed to offer many unique features.


Filter Features:

  • Maximum airflow - The filter design allow the use of high pressure blowers to overcome the resistance to airflow through a filter for much longer as the filter begins to block. This means the filters last longer.
  • Guaranteed unburstable - By employing reinforcing.
  • Design - The size, design and production technique gives more filter media surface area than in many other filters, thus extending life span.
  • Maximum filtration - In independent tests, these filters remove 99.997% of all particles above 0.3 microns and 95% down to 0.01 micron.
  • Flow equalisation plates - Help to distribute the airflow over the filter media and make the whole filter more robust.
  • Precise and rigid construction - Helps ensure that no fumes are allowed to pass around the filter and escape into the workplace.

Cascade Inline Filters

Purex Cascade inline filters have been designed for applications that produce a large volume of particulates which would quickly blocked other filters.


For example, continuous engraving of rubber, wood and some plastics can rapidly clog normal extractor filters leading to excessive replacement costs. Recognizing the problem of consumable filter costs, Purex International has designed the 'Cascade', a unique multi pocket filter with an innovative concentric cone design.

The Cascade sits in its own cabinet and acts as the first stage of filtration. Large particles and other containments are captured by the Cascade, the air (free of large particles) is then routed to the Purex fume extractor where the Labyrinth pre-filter and main Hepa/Chemical filters clean the air of remaining particles and harmful gasses.

With the large particles removed by the Cascade, the filter life of the Labyrinth and Main filters are greatly extended. The Cascade dramatically reduces the life time costs of consumable filters.

The Cascade features a special media surface that allows particles to collect without sticking. When the Cascade appears to be blocked, as evidenced by an alarm, the operator simply shakes the Cascade to dislodge any particle build up and the filter can be used again.


When the Cascade is finally full the operator can quickly and easily remove, empty and re-use the filter many times over.

How Purex filters capture gas... Gas / Vapor Filtration

Purex filters capture contaminant gases from the process by using some or a mixture of the following.

  • Activated Carbon-Alkali or Acid Impregnated
  • Alumina Permanganate

A gram of activated carbon can have a surface area in excess of 500 m², with 1500 m² being readily achievable. For comparison, a tennis court is about 260 m².


Under an electron microscope, the structure of activated carbon shows there are a great number of nooks and crannies, and many areas where flat surfaces of graphite-like material run parallel to each other, separated by only a few nanometers or so. These micropores provide superb conditions for adsorption to occur, since adsorbing material can interact with many surfaces simultaneously.

Alumina Permanganate is aluminium oxide impregnated with potassium permanganate, used as an oxidizing agent when mixed with carbon for MEK applications.

For more information:

  • Call Your Purex Representative: 877-276-1084
  • Or download a Purex Fume Extraction brochure
  • Or contact us via this form