Negative or Positive – Choose The Pressure That Works For Your Filter Application

In the health care, micro-electronics, micro-chip manufacturing, optics, food processing and other environmentally sensitive applications, the need for high end air filtration or HEPA filtration is high.For example, all hospital and out-patient surgery suites require 100% HEPA filtered air all the time whenever a patient is in surgery.

However, did you know that not only does the surgery room require HEPA filtration but it must operated under a negative pressure system?

The concept of negative and positive air pressure as a means to control an enclosed environment has been around for a long time. While we don’t always notice it, we all see this working on a day-to-day basis in the everyday world.

Remember the last time you opened the door to an office building and you had to pull real hard to get the door to open. Or, just the opposite. You opened the door to a building and when it opened up it blew your hair back. The first example is negative pressure, the second positive pressure.

A building or any enclosed room or structure can become negative when the air handling (heating/cooling) system has a design flaw where more return air is being pulled to the air handler than supply air.

This can happen mechanically for a number of reasons but suffice it to say that when this in-balance of air occurs any opening, crack, or communication point in the structure will draw in air, dust, dirt and any small airborne particulate from the outside or an adjoining space.

The opposite in-balance can also occur where there is more supply air than return air creating a positive pressure environment. In this case the room or enclosure maintains a much cleaner environment since the positive pressure prevents any outside contaminants from entering the room.

For applications such as surgery rooms and micro-chip manufacturing, the rooms must not only be HEPA filtered but be under constant positive pressure.

When a patient is in surgery and the body cavity is open the possibility for infection from any airborne pathogen is extreme. Even with all the air being HEPA filtered, if the room itself was not under positive pressure the ability for small, sub-micron contaminants to enter the room is great.

Micro-chip manufacturing has a similar problem. The micro-chips are actually layers upon layers of silica and if even a tiny, sub-micron particle falls in between the layers, the chip is ruined. Again, positive pressure is required in this application.

In applications where a harmful contaminants, highly infectious bacteria and viruses or harmful gases are present, negative pressure systems are applied to keep the contaminants from leaving the room or enclosed area.

Pure Air Systems HEPA filtration units are powerful and can be used to make a room negative or positive by themselves. They can also be used in conjunction with any HVAC system to accomplish this goal. The ability to both provide HEPA filtered air and produce the desired pressure in the room for the specific application make these systems unique in the market place today.

For more information on positive and negative pressure and the overall capabilities of the HEPA systems go to:

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How A&E Firms Utilize The Unique Capabilities Of PAS HEPA Filtration Systems

Architectural and Engineering firms offer engineering and design services primarily for the commercial, industrial and institutional markets.  They may design, engineer and/or specify the types of equipment, controls and materials required to bring a project to completion.

For projects that require some form of HEPA based air filtration for sanitary processes, drug manufacturing, food processing, clean room applications and medical product and health care facilities, A&E firms often work with and incorporate Pure Air Systems HEPA based air filtration systems.

The HEPA based filtration systems offered by Pure Air Systems ( PAS), offer some of the more unique capabilities and features of any HEPA based air filtration system on the market today. First, PAS makes some of the largest and most powerful stand-alone units incorporating both a three-stage filtration system along with the Genteq (GE) ECM variable speed 120/240 volt 50/60 Hz motors.

The three main units, 600HS, 1200HS and 2000HS systems are capable of moving from 100 to 600; 100 to 1200 and 100 to 2000 cfm respectively. Because they incorporate the ECM variable speed motor they can be applied to a wide variety of applications requiring HEPA filtration where specific volumes of air are required and the electrical requirements demand 240 volt motors.

The PAS units are also relatively small and light compared to their overall capabilities. The 600HS is only 97 lbs and the 1200 and 2000HS units weigh just over 200lbs. These units are configured in two different housing styles. One version is configured like an L with the inlet at the top and the discharge at the bottom side. The L versions are comprised of two separate sections that are symmetrical so the top and bottom section can be rotated for any inlet-discharge design requirement.

The S versions, or straight through versions, have the inlet and discharge openings at the ends. These horizontal units can be mounted vertically as well as horizontally and the 1200HS and 20ooHS units each have weld nuts located on the top four corners for ease of mounting.

From an Engineers point of view, the PAS units provide a unique blend of  performance, power, control and durability not found in any other HEPA filtration system today. The fact that the PAS units come standard with a scanned 99.99% at 0.3 micron HEPA filter, carbon media filter and ring panel prefilter means that these units can be applied to almost any application where true, certified HEPA filtration is required.

PAS has been making commercial grade HEPA filtration systems since 1985 and has more HEPA systems installed in commercial applications in North America, Europe and Asia than any other HEPA filtration company. For more information on the complete line of HEPA and Carbon based systems offered by PAS go to our website:

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Time To RE-Think Your Furnace Filter System

No matter what type of forced air heating/cooling system you use, all of them require an  air filter of some kind.  While many people believe the primary purpose of the filter is to remove airborne dirt and dust particles to keep the home or office environment cleaner, the fact is the filters  are used primarily to keep the heating/cooling system clean.

All split system HVAC units have a cooling coil for AC and sets of burners for heating located in the main air handler. It is necessary to keep the cooling coils and burners clean and free of dust and dirt or they will not operate properly and become very inefficient. In addition, the air filter is needed to keep the blower wheel ( the device that moves the air) from getting dirty and out of balance. Also the furnace fan and motor are designed to move the air through the system and compensate only for the static pressure or resistance for only these components. The filter can not add much static load to the fan.

It is for these parameters that most furnace air filters are designed and that is why the majority fall under one of two categories; “crappy” and “almost useless”. Yes, they can remove enough of the larger dust and dirt particles to keep the coil and burners clean but No, they are not dense enough to remove the smaller more harmful airborne particles. Making the filters too dense adds too much static load to the HVAC motor and significantly reduces the air flow and this means you heat or cool longer to obtain the desired room air temperature.

While there are a large number of expensive electronic, hybrid electronic or other media type filters available for use with you HVAC unit, for those of you who want to continue to use a simple, inexpensive, throw-away media filter for your furnace there is a better choice.

Pure Air Systems offers a dual-layer, polyester, ring panel filter that is commercial grade and fits tightly in the filter frame, holds a large amount of dust and dirt, collects particles as small as 3 microns and adds very little resistance or static pressure to the HVAC  blower/motor assembly.  These filters are easy to change and have an unlimited shelf life.

In addition, Pure Air Systems offers a line of filters using the same ring panel design with polyester media on one side and carbon media on the other side. These filters are great for both removing airborne particulate as well as odors and gases.

For more information on these filters and the other filter systems offered by Pure Air Systems go to our website at:

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Green HEPA Filtration Systems

Everyone, everywhere is now jumping on the Green bandwagon, and for a good reason. The green environmental movement has captured the hearts and minds of the younger generation and has pushed its way into every aspect of federal, state and local politics. The new business mantra is, ” it must be green or environmentally appropriate”. Not everyone agrees with this premise, but to be sure, it has garnered world wide attention.

In the US the new requirement for building construction is that they must now meet the LEED requirements and be LEED certified to meet the new green environmental building business model. The LEED system has been used in the residential market for the past three years.

When Pure Air Systems was founded in 1985 there was very little interest in the environmental movement and the term “being Green” was mostly associated with Kermit the frog.

However, since its beginning, Pure Air System’s HEPA filtration units were designed to be environmentally friendly. We like to say that” Pure Air Systems was green when green was just a color!”  The use of all steel cabinets to house the filters and blower/motor were designed to last the life of the unit. Meaning, all the interior components could be replaced indefinitely or until the all steel housing fell apart. This meant that the largest component that used the most energy to make and materials to construct would not have to be replaced often.

In addition the blower is constructed of galvanized steel so it won’t corrode in any type of environment. And the Genteq (GE) ECM variable speed motors use up to 50% less electricity than standard induction motors and in most cases only the control end part of the motor needs to be replaced so the largest part of the motor remains with the unit.

When you look at the construction of the HEPA systems you can see that these units use sustainable materials, low energy use motors and overall a very small carbon footprint. The HEPA systems also meet many of the requirements for LEED certified buildings, structures and homes.

For more information on the PAS HEPA systems please go to our website at:

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Home Health Care

You can’t pick up a newspaper or magazine or go on-line today without reading about health care. While much of the commentary is on changes to the health care system, a lot is also pointed toward the ways we can reduce health care costs by taking better care of our bodies.

While knowing more about how to maintain a healthy lifestyle is important, it is just as critical to become better educated on how to maintain a healthy home.

Since we spend the majority of our lives inside our homes breathing the air in this enclosed, controlled environment, shouldn’t we know more about how this environment can affect us? I think we should. After all, breathing in even small quantities of airborne allergens, pathogens and gases over time can significantly affect you health.

New home construction techniques have made homes tighter and more energy efficient, they have also significantly reduced the amount of fresh air exchange while significantly increasing the concentration levels of all types of airborne contaminants. Yes, your furnace filter does remove some of the larger dust particles and yes some of the more sophisticated hybrid type electronic cleaners are more effective on smaller particles. However, both of these systems require you to run your furnace fan constantly to keep the airborne contaminants coming to the filters, and, neither of these filter systems allows for any fresh, filtered outside air.

Airborne contaminants, allergens, pathogens and gases are generated on a daily basis in all homes. Carpeting, cleaning chemicals, pets, hair spray, dust from clothing, books and outside the house and our own bodies, all contribute to this indoor air pollution.

Because the majority of these harmful particles are tiny, less than 20 microns in size ( the human eye can only detect particles about 100 microns in size) they are not visible therefore not noticed. Yet a large majority of these small particles are inhaled into our lungs and stay there. Our bodies naturally remove most of these but some can be harmful and some of the airborne allergens and pathogens can cause significant respiratory problems or severe allergic reactions that can become chronic.

Pure Air Systems has been manufacturing true, commercial and hospital grade HEPA based air filtration systems since 1985. These systems are designed to be installed as part of the HVAC system (heating/cooling unit) and filter all the air in the house up to 48  to 60 times per day. In addition, these units have the ability to introduce fresh, filtered outside air into to house.  The HEPA filter is designed to remove 99.99% of all particles 0.3 microns and larger and approaches this same level of efficiency on particles as small as .012 microns.

This unit can be used in conjunction with any type of forced air heating/cooling unit and the PAS units use the energy efficient ECM motor that can run continuously removing airborne contaminants 24/7  and operating for only pennies a day.

The cost of health care is one of the most critical issues we face today. Pure Air Systems has one solution to help you keep you home healthy and you healthy at the same time.

For  more information on the PAS HEPA systems go to.

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HEPA Filtration For Your Laboratory

With the increasing number of medical, chemical and biological laboratories now operating in the US, it is more critical than ever to ensure both the safety of the lab personnel and the quality of the tests being performed.

With the drive to develop more and better drugs, chemicals and biological agents to compete in this global market, laboratories in the Pharmaceutical, governmental, educational and military sectors are using more sophisticated equipment along with more virulent, toxic and extremely dangerous pathogens for testing and product development.

While many of the more sophisticated and well funded operations use high end HEPA and ULPA filters to protect the technicians, many of the smaller laboratory operations use minimal ventilation and often no filtration systems or filters of any kind. This can and does lead to worker health problems as well as cross-contamination and expensive loss of product .

In the past, the cost of installing HEPA filter systems or HEPA ventilation systems was costly and took up valuable space. Today, Pure Air Systems offers a complete line of self-contained, fan-powered, commercial/hospital grade certified 99.99% at 0.3 micron systems ranging from small portables that produce as little as 150 CFM to large units with capacities up to 2000 CFM.

The new HPS series portable units have a four speed motor and can move from 150 to 500 CFM in a unit that is only 13″ square and 21″ long. These new high end portables  are engineered to be used in laboratory operations and in small, confined areas. The size, weight and variable volume controls allow this unit to be used in a wide variety of applications and the cost is less than $1,200.00.

For larger areas the 600, 1200 or 2000 series Pure Air Systems units can be applied. Each of these units comes with a Genteq ECM variable speed 120/240 volt 50/60 Hz motor with digital controller for volume control from 50 CFM to 2000 CFM in 1% increments. This fine tuning of HEPA filtered air is not available from any other HEPA filter manufacturer.

For more information go to or contact Pure Air Systems directly at: 800-869-8025

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Carbon Adsorption – How Does It Work?

The use of carbon media for reduction and removal of odors and gases has been around since the turn of the century. For the most part carbon and charcoal are the same thing. Carbon used for adsorption of gases is normally expanded by using a combination of pressure and heat. This expanded carbon provides for a large surface area on each carbon granule allowing each granule to adsorb up to 100 times its weight in gases.

Carbon has a natural affinity to attract and retain a wide range ( hundreds of types) of organic and inorganic fumes and odors. As the gaseous molecule passes by the carbon it is adsorbed into the carbon media and retained until that carbon granule is saturated at which time the carbon will no longer adsorb any more ( like a sponge).

The life of the carbon (ability to adsorb) is based on a number of factors. The type of gas or odor, the molecular weight of the gas, volume of air and the concentration of the gas, usually measured in parts per million (ppm).  While all of these variables are important in designing a carbon system the most important is the concentration in and the required reduction or concentration out.

If you want to reduce a continuous air flow containing 30 ppm of styrene monomer to 4 ppm at a volume of 500 cfm and you only want to change out the carbon once every month, you may require as much as 60 to 80 lbs of carbon. Remember, once the carbon is saturated it will release any additional gases back into the air stream.

Pure Air Systems offers a wide range of carbon adsorption systems and specially treated media for unique adsorption applications. We offer a line of combination prefilter/carbon media filters that can be used in-lieu of furnace filters for residential and commercial applications.  In addition, all of our fan powered units, from our portable HPS series to our 2000 CFM units can be fitted with up to 80 lbs of carbon media and used in a wide variety of gas reduction/removal applications.

For more information on our complete line of carbon adsorption units and technology go to our website at: www.pureairsystems. com.

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H1N1 Capture

Like any airborne pathogen, the H1N1 virus is easily spread by contact from person to person in the air. While  it is always a challenge to keep from getting into contact with a carrier there are options available for reducing or removing the virus in small, enclosed areas.

The ability to remove the virus in say, a classroom or hospital ward is now possible with the use of the new commercial, hospital grade HPS series portable HEPA filtration units by Pure Air Systems.  These new high units (up to 500 cfm) can be placed anywhere in a room and provide from 3 to 10 air changes per hour. The new HPS units use a true, certified, scanned HEPA rated at 99.99% at 0.3 microns and smaller.

With the high incidence of H1N1 flu on college campuses and in the elementary schools, the use of HEPA filtration systems like the HPS series could help reduce the exposure of the flu to a number of students and individuals.

For more information on this HEPA unit and the other commercial HEPA systems offered by Pure Air Systems go to our website at:

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PAS Sees 60 % Increase In International Business

Sept 1, 2009

Indianapolis, Indiana


Pure Air Systems Ships HEPA Filtration System To Japan

Since 1985, Pure Air Systems has been designing, manufacturing and marketing its line of high end, commercial grade certified HEPA air filtration systems. Residential, commercial, institutional, military and industrial customers around the world have used the PAS systems for reduction and or removal of airborne contaminants as small as 0.012 microns in diameter. Pure Air Systems was the first air filtration company to incorporate the GE (Genteq) ECM digitally controlled variable speed motors that are rated 120/240 volt, 50/60 Hz. The addition of these global application motors gave Pure Air Systems the ability to market the complete line of HEPA based filtration systems to companies anywhere in the world.

In June of 2009 Pure Air Systems received an order from Yaw Automation in Osaka, Japan for one of its’ 2000HS series HEPA systems that produces up to 2000 CFM of HEPA filtered air. Yaw Automation is using the 2000 HS unit in one of their automated process lines that requires a close to clean room environment. The 2000HS, with its variable speed motor and digital speed controller, allow the Yaw engineers to fine tune the amount of HEPA air required for their specific application.

In addition to the Yaw Automation in Japan Pure Air Systems has recently shipped systems to Cure International for its Hospitals in Niger and Malawi Africa; Natural Products Pharmaceuticals in South Africa and Vemco, Ltd in Trinidad and Nano Diamond Products in Ireland.

For more information on the complete product line from Pure Air Systems and a list of our US and International commercial clients please go to our web site at:

IBJ Article On Pure Air Systems and International Markets

Pure Air Systems

6115 Guion Road

Indianapolis, IN 46254

800-869-8025,  317-291-4341


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Effectiveness Of HPS 500 For Formaldehyde Removal





The Department of Homeland Security, Federal Emergency Management Agency is researching the logistics and costs associated with the remediation of formaldehyde-contaminated manufactured housing and recreational vehicles. The DHS is requesting information from industry to determine its ability to remediate formaldehyde-contaminated manufactured housing and recreational vehicles.

Over the years, FEMA has procured manufactured housing and recreational vehicles which are located throughout the United States. Manufactured housing and recreational vehicles are in the form of park models with average dimensions of 14 ft x 40 ft; travel trailers averaging 8 ft x 32 ft; and mobile homes averaging 14 ft x 65 ft. FEMA has determined the manufactured housing and recreational vehicles are not suitable for residential use/habitation. FEMA is researching the logistics and cost associated with reducing the formaldehyde concentration in the manufactured housing and recreational vehicles to a level of 0.16 ppm or below, and maintaining that level indefinitely.


Established in 1985, Pure Air Systems has been manufacturing HEPA and Carbon based air filtration systems for the residential, commercial, institutional and medical markets. We have systems in operation in a number of government associated facilities such as; Lawrence Livermore National Labs, NASA’s Jet Propulsion Labs, BAE Defense Systems, U.S. House of Representatives, U.S. Navy, U.S. Army, Picatinny Arsenal and U.S. Boarder Patrol to name a few.

For applications where the reduction/removal of odors and gases are required, we remove the HEPA filter from our systems and replace it with various carbon and adsorption based compounds specifically suited for removal or reduction of specific gases.

For the purposes of this specific project we used our new portable HPS 500 unit that can move over 500 CFM of air. The HPS unit is 13” square and 21 ½” long and weighs approximately 28 lbs as used in this test phase. We installed three filters in the HPS 500 for this test phase.

The first filter is a combination 12” x 12” x 1” ring panel polyester media on inlet side and carbon media on discharge side. This first filter is designed to remove dust particulate and keep the adsorption media clean. This first filter contains 76 grams of activated carbon.

Page 2: Formaldehyde Test – Pure Air Systems

The second filter is a 12” x 12” x 2” box style pleated material that contains 294 grams of activated alumina with 5% potassium permanganate.

The third filter is a 12” x 12” x 4” box style pleated filter material that contains 374 grams of activated alumina with 5% potassium permanganate. The three filters combined have a total of 744 grams of adsorptive media.


The three adsorptive media filters were placed in the HPS 500 series unit. (see photos last page). This system uses an EBM four speed blower/motor assembly that can produce well over 500 CFM with all filters installed. For the purpose of this remediation test we ran the unit at the lowest speed of 200 CFM.

The HPS 500 was placed in an 8x8x8 plastic enclosed room that was almost air tight. (see photos last page). The test room is located in a warehouse space and the space is not cooled or heated. The tests were done from June 10th through June 24th. The average temperature in the room was 84 degrees with an average relative humidity of 50 %. This is fairly close to the conditions you would find in a mobile home or recreational vehicle that is closed up with no ventilation or operational heating/cooling system in the same seasonal time period in most parts of the U.S.

A stand was placed in the middle of the test room and a section of carpet was placed on the stand. We used a 37% solution of HCHO (Formaldehyde) (Formalin) solution reagent for the purpose of replicating as closely as possible the type of Formaldehyde used in certain building materials found in the construction of mobile homes and recreational vehicles. The HCHO was purchased from Spectrum and is listed as: CAS 50-00-0.

To accurately measure the levels of Formaldehyde in ppm, we used a Sensidyne Gastec sampling pump, model 800. (see photo last page). To measure the gas levels we used Sensidyne Precision Gas Detector Tubes, Number 171SC for Formaldehyde. Range 0.05 to 4.0 ppm. Lot No. 252019. Tubes have an expiration date of Jan 2010.


To establish a base level (in ppm) of Formaldehyde that would be representative of HCHO levels that may be present in mobile homes, travel trailers and recreational vehicles as indicated in the overview of this report. Our own experience with testing for Formaldehyde in homes and mobile homes has shown levels that range from 5 ppm. Since the Sensidyne tubes have a maximum range of 4.0 ppm we ran a number of tests to determine the amount of Formaldehyde needed in the test chamber to start with a base level of 4.0 ppm.

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TEST A: Date: June 10, 2009; Time: 10:00 AM

A piece of carpet was placed on a stand in the middle of the test chamber and the appropriate amount of Formaldehyde was placed directly on the carpet piece. The chamber was closed up for four (4) hours prior to taking the first reading. The HPS 500 did not run during the four hour saturation process.

Time: 2:00 PM

The first reading was taken (HPS not running): Base level of 4.0 ppm HCHO achieved.

Time: 2:01 PM

HPS 500 was turned on with fan running at lowest speed setting ( 200 CFM).

Date: June 11, 2009; Time 2:00 PM

Second reading taken after HPS 500 ran for 24 hours in test chamber. HCHO reading 0.3 ppm.

Date: June 12, 2009; Time 2: 00 PM

Third reading taken after HPS 500 ran for 48 hours in test chamber. HCHO reading 0.05 ppm.

TEST B: Date: June 15, 2009; Time 9:00 AM

Dispersion Test. The same protocol was used for this test as used for the HPS 500 carbon reduction/removal test. The purpose of this test is to determine if, over time, the levels of Formaldehyde will decrease or remain the same if no active reduction/removal process is used. The same amount of Formaldehyde was introduced by applying it to a piece carpet located on a stand in the center of the test chamber.

Time: 1:00 PM

The first reading was taken: Base level of 4.0 ppm HCHO achieved.

Date: June 16, 2009; Time 1:00 PM

The second reading was taken after 24 hours: HCHO reading 4.0 ppm.

Date: June 17, 2009; Time 1:00 PM

The third reading was taken after 48 hours: HCHO reading 4.0 ppm.

Page 4: Formaldehyde Test – Pure Air Systems


While this test was concluded in a test chamber rather than an actual mobile home, trailer or recreational vehicle, the environmental conditions and levels of Formaldehyde used in the test chamber mimic, in many ways, the actual conditions we have found in homes and mobile homes in actual in-situ testing.

We only ran the tests over a 48 hour time frame since we only used a small amount of Formaldehyde. This represents, more or less, an equivalent amount of Formaldehyde that would be representative of an entire unit where much of the construction materials would contain some Formaldehyde and the overall concentration, dispersion and out-gasing would last for a much longer period of time. The dispersion test verified that there is little or no decrease in the HCHO level without any active reduction/removal process. Based on these tests in can be concluded that the HPS 500 with the adsorptive media as tested would maintain the levels of < 0.05 ppm indefinitely.


The next test for the HPS 500 would be in an actual DHS formaldehyde – contaminated mobile home, travel trailer or recreational vehicle as indicated in the original solicitation. With the positive results of the Formaldehyde reduction/removal testing as shown in our test report Pure Air Systems believes the use of the HPS 500 would be a much better and much less expensive than removing and replacing all the wall and floor construction materials.

Page 5: Formaldehyde Test – Pure Air Systems.

HPS 500

Pure Air Systems Test Chamber

Sensidyne Test Tubes

Page 6: Formaldehyde Test – Pure Air Systems

Carbon Media and Alumina Media With 5% Potassium Permangenate

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