Delta P Is Not A Fraternity

It is always interesting to see the amount of new technology being developed every day. New computing devices, new 3-D TV’s, new ways to generate energy and yet we understand so little about how these systems actually work. We just assume that when it says to push the red button the system will turn on or off or clicking on this URL will get us to internet nirvana.

This lack of interest in actually knowing “how things work” can be to our detriment. If we don’t know the how or why of a product or system we will make a buying decision based solely on looks and price. For some items this is appropriate. But in many cases some basic research on the product or system is warranted.

Take for example the term “Delta P” or sometimes it is written out using the pyramid symbol with the P following it. This term means pressure differential, pressure drop, resistance in air flow as measured in inches of water and has a lot to do with some products you buy. Specifically air filtration systems and their relationship to their performance and performance of systems they are attached to.

Air filters or any type, style or media make up all create a certain amount of resistance when placed in an enclosed device like a furnace filter in a filter frame or a filter in a fan powered air filtering (air purifying) device.

When the filter is placed on the air entering side of the fan or air moving device it will create some resistance or increase the amount of pressure the fan has to see in order for the air to move through the filtering device. This pressure drop or Delta P is important as it affects both the air flow performance of the heating/cooling system or the filtering device itself.

When you have an air moving device like the fan in the heating/cooling system, the fan/motor assembly is designed to move a certain amount of air ( measured in CFM) at a specific pressure drop or resistance ( measured in inches of water). Let’s say the fan is designed to move 1200 CFM at .5″ of water. This is with a general duty, Walmart fiberglass furnace filter( this filter has a rated pressure drop clean of  .1″).

If you want to install a better, more effective filter in the system, say a MERV 9 or 10 filter, this media has an initial resistance or Delta P of .4″ . This means the furnace fan will have to work harder to pull the air through this filter. If the motor/blower system is only designed to move 1200 CFM at .5″ or .6″ then something has to give. What happens is the furnace fan actually backs down due to the increase in pressure drop and the air flow is reduced. Depending upon the type of fan and motor being used in the HVAC unit the air flow can be reduced by as much as 100 CFM per additional .1″. So if you add .3″ of static that the fan system is not designed for, you can reduce the air flow by 300 CFM.

This air flow reduction is significant in that it now requires the system to run 30% longer to either heat or cool the house due to the additional resistance across the filter. When using filter media such as HEPA filters the initial resistance across these filters can be as high as 1.0″. So it is important to understand the relationship between air flow and Delta P.

For more information on this subject matter and information on the complete line of HEPA filtration systems offered by Pure Air Systems please go to our website at:

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I’ve Got You Under My Skin

As part of the natural repair functions our bodies go through each day, one of those  necessary functions is both good and bad. Each day the body sheds over 1,000,000 skin flakes from your body. This is a natural process that allows the old, used skin cells to flake off (so to speak) and be replaced with new skin cells.

Again, this process takes place every day for everyone of us. So, for example, if you have a family of four they will generate 4 million skin flakes a day. These skin flakes range in size from less than 1 micron to 30 or 40 microns in size. Over 30% of the dust you see in the air ( dust particles in the sunlight through the window) are skin flakes…… Oh yes they are!

Okay! So what happens to these skin flakes? Well, some of them are picked up by the vacuum and those that stay airborne may be removed through the filter in located in the return air side of your heating/cooling system. The rest are eaten. Yep, eaten by dust mites.

For all the bad press the dust mites get ( and there is a reason for that)  they are natures own trash disposal system. You see, dust mites feed off of skin flakes.  We call them dust mites since the term “skin flake mites” is too long and rather disgusting. Yet, that is exactly what they do. Munch on your dead skin!

When your body is at rest whether sleeping, or sitting on the couch, your skin cells are being shed. These flakes tend to stay in place longer and thus become the better feeding grounds for dust mites. When the dust mites eat your dead skin they produce small pellets or fecal matter. They produce up to 20 of these digested skin pellets each day. It is these pellets or “dust mite feces” that affects millions of allergy sufferers.

Dust mites themselves are relatively large so they seldom become airborne. The dust mite feces or pellets are very tiny easily become airborne.  They are aspirated into the body through the lungs and for many people these pellets can cause some severe allergic reactions for a number of individuals.

No matter how often you dust, vacuum and clean your home you will have some of these dust mites in your enclosed living environment.  Since the main allergen is the dust mite feces, the removal of these tiny pellets is essential.

Since the dust mite feces is light and can be airborne it is essential that the filter or filtering device you have in your heating/cooling system be effective on removing small, less than 10 micron sized particles. In addition, you need to keep the fan in your heating/cooling system to run all the time so setting the fan switch to “fan on” on your thermostat will keep the air moving and continuously draw the airborne particulate back to the filter.

Pure Air Systems has been making HEPA and Carbon based air filtration systems since 1985. These commercial grade HEPA units are designed to attach to any forced air, ducted heating/cooling system and can remove 99.99% of all airborne particles 0.3 microns or larger. These systems are extremely effective at removing dust mite feces and other airborne allergens.

For more information on the complete product line please go to our website at:

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First Rate HEPA Systems For Third World Countries

Health care is currently a hotly debated issue in the U.S. Our health care system is considered one of  the best in the world and leads the world in developing new drugs, surgery procedures and medical equipment. The surgery rooms are state-of-the-art and incorporate the best HEPA filtration systems to minimize the possibility of infection during surgery.

In the developing countries and third world countries, especially those in Africa, health care is not readily available to much of the population and what is available is sometimes rudimentary at best.

One of the primary killers in any U.S. hospital is infection, specifically post operative infection. This is why the surgery suites and operating rooms are kept under 100% Hepa filtered positive pressure air. This helps to keep any bacteria or airborne pathogen from getting into the operating room when the patient’s cavity area is exposed.

In most third world countries there is little money available for hospitals and high-tech surgery rooms. Even worse, there is little to no air filtration available for these facilities. Infection is one of the main challenges in these facilities.

Pure Air Systems has been designing and manufacturing commercial grade HEPA systems since 1985 and is considered one of the leaders in high volume, digitally controlled HEPA and Carbon based systems.

PAS uses the new ECM variable speed 120/240 volt, 50/60 Hz motors in all of its larger units. These motors are designed to operate anywhere in the world. Since most countries, other than the US, use 220 volt and 50 HZ electrical current the PAS line of HEPA systems are perfectly suited for these locations.

The African continent is no different. Their hospitals use  220 volt 50 HZ for their electrical power. The PAS line of HEPA systems have a air flow range from 600 CFM to 2000 CFM and with the use of the digitally controlled motors these volumes can be adjusted to any flow for any requirement.

Since the PAS units are fan powered they can be used as stand-alone systems or used in conjunction with a ducted heating/cooling system. In many of the African hospitals they are used as stand-alone units usually located inside or adjacent to the surgery room and then designed to filter all the air in the room through the HEPA system with a small amount of air introduced through the unit from outside the room to ensure the surgery suit is not only 100% filtered but also under positive pressure.

The cost of using even the largest of the PAS HEPA systems is 1/100th the cost of having to build an entire HEPA  based ventilation system for these surgery suites. More importantly, the PAS units are small enough (weighing 200 lbs) that they can be used even in remote, temporary facilities or in mobile hospitals.

For more information on the complete line of HEPA and Carbon based systems offered by Pure Air Systems and a listing of international locations where these units are used please go to our website at:

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Beam Me Up Scotty!

Space. The final frontier. These are the voyages of…….lost in space. Walk into room and can’t remember why you went there? Have that fuzzy kind of brain doesn’t seem to be working day? Maybe a senior moment…but you are only 35? Feel lethargic? Can’t concentrate? What the heck is going on?

Interesting thing about Oxygen..too much or too little can be lethal. The right balance of 21% Oxygen and 79% Nitrogen keeps us humans happy and healthy. The right balance of CO2 in the atmosphere is also critical to our happiness and well being.

Spatial Disorientation….a new frontier. This is the more common syndrome caused by a lack of fresh air or oxygen and too much CO2, or stale air. Most people experience this in schools, offices or homes where there is little or no fresh air exchange taking place. When you have room that is full of people the amount of CO2 goes up and the amount of O2 or oxygen tends to go down if there is no method of introducing outside fresh air.

The typical symptoms of this problem include, lethargy, headaches, inability to concentrate, foggy/groggy feeling and total lack of focus. This is why many of the older schools in the US that had through the wall heating/cooling units and no central systems to introduce fresh air  had so many students falling asleep or having significant problems concentrating in class by the middle of the afternoon.

The majority of the homes that have been built in the last 10 to 15 years in the US have incorporated new energy conserving building technology and materials to keep the house warmer or cooler using less energy. These “tight” homes also have little or no natural ventilation which means no way to introduce any fresh air into the living space.

While the ability to introduce outside air through “economizers” incorporated in many of the commercial HVAC systems used in commercial building is fairly common, this is not the case for the residential market. Unless requested by the home owner, fresh air dampers or mechanisms designed to introduce outside air through the HVAC unit are never installed in homes. And for good reason.

When the outside air temperature is higher or lower than the inside ambient temperature it makes little sense to introduce cold or hot humid outside air into the house since you will now have to expend more energy to heat or cool that additional outside air. Yet, with the tightness of the homes, some effort should be made to introduce small amounts of  outside, fresh conditioned air into the home.

Pure Air Systems has been making HEPA based, fan powered air filtration systems since 1985. These units are designed to either attach to an existing heating/cooling unit or as stand-alone systems. PAS HEPA units are attached to the heating/cooling units using the partial by-pass concept. In this way they pull a small portion of the total return air flow and filter it before putting it back into the supply side. These units can be used to introduce small amounts of outside air, filter it and mix it with the return air from the HVAC unit and then introduce it  back into the house…..without using more energy to heat or cool.

For more information on the complete PAS product line and their capabilities please go to our website at:

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The Answer Is Blowing In The Wind

We always dream of laying on a sunny beach somewhere watching the light, tropical breezes blow through the palm trees. For some reason the movement of air through the trees or fields of wheat or tall grass creates a sense of calm and peace. Yet strong, cold winds blowing off snow or water into our face creates shear misery.

Producing wind or air movement via the use of various types of fans has been around since the early 1900’s. With the invention of the small, electric motor fans became more popular and the preferred way to provide cooling for people, animals and machines. As the design of fan blades, motors and digital controllers improved, fans found their way into the majority of homes, offices and schools.

With the ability to control fan speed and direction, ceiling fans are now the preferred method of moving air to keep it from becoming stale or stagnant. In addition, the fans aid in moving cool and warm air through various rooms in the house in the summer and winter months. However, aside from moving air and adding some comfort, fans also create some environmental issues that should be considered.

When a ceiling fan or box fan is moving air in a room or large area is it also moving any of the airborne particulate that is suspended in the air. While sometimes this can aid in keeping the dust airborne until it is picked up by the return air ducts and then filtered in your HVAC unit, this constant dispersal of dust also keeps it up in the breathing zone.

For people with allergies due to dust, pollen, ragweed, animal dander, dust mite feces, etc, running a ceiling fan may not be in your best interest. The airborne contaminants are extremely small and light and easily picked up off the floor, furniture and other flat surfaces and then redeposited on other surfaces, including beds and sofas.

When dusting or running a vacuum it may be a good idea to turn off all the fans. No matter how good a dusting cloth or how efficient the a vacuum, the process of cleaning will always disturb some of the dust. Even with HEPA filters, good vacuums will discharge a fair amount of small, sub-micron particles into the air while cleaning the carpets and floors. Again, the fans will just put this residual dust back on the same surfaces you just cleaned.

Pure Air Systems has been making HEPA and Carbon based fan powered air filtration systems since 1985. They have a complete line of systems that can be either attached to an existing HVAC system or used as stand alone units. In addition, PAS offers a line of portable HEPA units that can be used for single room or large area applications. For more information please go to our website at:

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For Good Indoor Air Quality – Green Is More Than A Color

You can’t go anywhere or read any newspaper, magazine, billboard or internet material without the term “Green” being used. And we are not talking about the mixing of blue and yellow to get the color green….we are talking about the save the planet, save the environment, save you life (through healthy practices) green.

Whether you agree or not, green is in……WAY in. The concept of using green as a way to sell products is now being used by almost every product manufacturer in the US and overseas. There is no doubt that the use of non bio-degradable chemicals and materials has become a very large problem. Companies that produce household cleaning products, for instance, have changed the formulas to ensure that all the chemicals used in the product are non-toxic, safe and biodegradable. Even the containers have been changed to be ‘landfill safe.”

For those individuals who suffer from various allergies, asthma, chemical sensitivities and respiratory dysfunctions, going green can significantly improve your indoor air quality.

For those individuals who have certain chemical sensitivities there are products for washing floors, clothes, counter tops, bathrooms and yourself that no longer have any chemical smell and are not artificially scented. Cooking utensils, small appliances, chairs, tables, etc,  are now made of materials that don’t use petroleum as a base chemical. Bedding, pillows, curtains, covered furniture, carpeting and clothing is now made with natural fibers and are  hypo-allergetic.

For those individuals who like plants in the house but also suffer from allergies due to pollen, ragweed and certain mold spores, there are new artificial plants ( greenery) that look real, feel real and are attractive. Real plants need to be potted in dirt or special soils and require plant food. Also, they require water. While it may not seem to be a problem, there are numerous natural mold spores that live and thrive in the soil and can be an issue with certain allergy sufferers.

There are also new ways to heat, cool and reduce humidity in your home while saving energy and providing for a more comfortable, healthy environment. There are now “smart” heating/cooling systems that can more accurately and more efficiently heat and cool your home and maintain a more comfortable moisture level no matter where you live.

Some of the newer light bulbs and lighting systems are designed to provide for a softer, more indirect form of lighting to minimize the glare, eye strain and headaches caused by too much of the wrong type of light. These light bulbs and systems use up to 50% less energy than the standard lights and are fast becoming standards in many countries around the world.

Going green has been the basic mantra for Pure Air Systems since its inception in 1985. Pure Air Systems was green when green was only a color. PAS manufacturers a line of HEPA and Carbon based air filtration systems that use all metal housings, commercial grade metal framed HEPA filters, non-toxic carbon media and the ECM motors that use magnets rather than windings to both use less electricity and produce less ozone.

For more information on the complete line of air filtration products offered by PAS please go to our website at:

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Chemical Sensitivities and Your Environment

For many of us dealing with the the typical spring and fall allergy seasons is a given. We know that mother nature can be both beautiful and nasty in the spring when the flowers are blooming and the grass is growing. There are many new medications that help in minimizing the allergic reactions and even allow us to venture outdoors on days when the pollen and ragweed levels are high.

However, for people who are chemically sensitive, the physical affects are not that easily relieved. Chemical sensitivities is somewhat of a grey area. Many chemically sensitive people don’t have a challenge with pollen or ragweed but can react to common household chemicals like bleach or even scented candles. And unlike the common symptoms of pollen and ragweed sufferers, the chemically sensitive individuals may have more severe reactions that include inability to breathe, skin rashes, metal tastes in their mouth, headaches, muscle aches, blurred vision and spatial disorientation.

For people who have these chemical sensitivities their lives are literally dictated by how well they can control the environment in which they live, work and play. The elimination or reduction of items in the home is relatively easy for the chemically sensitive individual.  Trial and error is the best guide. But, once they venture outside their chemically controlled environment they are at the mercy of the outside world of chemical soup.

To the chemically sensitive individual, the term fresh outside air is a misnomer. Their outside consists of automobile and truck exhaust fumes, chemical odors from manufacturing and processing operations and the spraying of fertilizers and pesticides in residential, farming and commercial areas.

When they go to work, they are subjected to a wide variety of chemical odors and gases. Their co-workers after shave or cologne. The chemical odor from clothes that are dry cleaned. The gases given off by copiers, printers and office supplies. The list goes on and on.

Being inside any gym, or work out facility presents similar challenges as does attending indoor sporting events where even the odors and gases coming from the concession stands can be significant issues. To the chemically sensitive individual home is usually their only safe haven.

Unlike the pollen or ragweed sufferer who can take one of the many over the counter medications that minimize or eliminate the “hay fever” type symptoms, the chemically sensitive individual has no such magic bullet. They simply need to totally eliminate from their environment those chemicals to which they are sensitive.

Since 1985 Pure Air Systems has been making HEPA and Carbon based air filtration systems for the residential, commercial, institutional and industrial markets. PAS was one of the first companies to offer Carbon adsorption systems for people with chemical sensitivities. Some of these carbon products were specially treated to remove specific gaseous compounds and most we designed to be benign to the customer.

For more information on the complete line of HEPA and Carbon systems and detailed information on the removal or reduction of various airborne chemical gases please go to our website at:

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I Love My Pets But They Don’t Love Me!

Americans have a very strong love affair with their pets. We spend over 4 Billion dollars a year feeding, grooming and keeping them healthy and happy and for many of us they have become our best friends. And the types of animals we keep as pets has broadened to include snakes, turtles, iguanas and birds of all types, sizes and varieties.

We take our pets everywhere we go; on planes, trains, in the car, on our bikes, to outdoor restaurants, to parks and in some cases sporting events. We take them everywhere and they love it. Aside from the unconditional love we get from our pets they also give us animal dander and other allergens that can be significantly challenging to us humans.

It is interesting to note, that of all the allergies that people suffer from, allergies caused by animals (dogs, cats, birds, etc) are second only to ragweed and pollen. Cats, for example, produce cat dander, tiny flakes of skin that have a protein that can cause itchy eyes, skin rashes, runny nose, congestion, wheezing and sneezing. Dog dander is not as strong an allergen but some people do have similar reactions to dog dander as they do to cat dander.

Birds are another issue. Like cat and dog dander, bird dander and their feathers are very light and stay airborne for long periods of time. Keeping birds in a small enclosed area will tend to concentrate the bird dander in one area. When you are in that area you will be exposed to the higher concentrations of the dander. Allergies to bird dander are similar to those caused by cats and dogs.

Pure Air Systems has been manufacturing HEPA based air filtration systems since 1985 for the residential, commercial, industrial and institutional markets. Many of the HEPA based systems sold to homeowners are used specifically to assist in removing/reducing the concentrations of animal dander in the air.

It is interesting to note, that many of Pure Air’s customers who have cats and know that they are allergic to cats, will keep the cats knowing that the HEPA filtration system is removing a significant amount of the airborne dander.  This is also true of dog and bird owners. For the most part,  pet owners will do everything they can to keep their pets in spite of the allergy issues. Only if the pet owner is so sensitive to the specific pet that even petting them causes some allergic reaction, then and only then will they make the decision to give up their pet.

It is necessary to consider your own health issues and issues of other family members as is relates to allergies to pet dander especially if the reactions are significant and can cause severe respiratory issues. We know you love your pets, but sometimes you may have to practice some tough love and make a decision that is best for you and your family in the long run.

For more information on the complete line of HEPA and Carbon based filtration systems and allergy issues, please go to our website at:

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Hydrostatic Water Pressure

One of the reasons that fluids, like oil and water, are used as mechanisms to move large, heavy objects is that they are not compressible. That is, when placed in an enclosed vessel or tube or hose and pressure is added (usually via a pumping device) these fluids will push or move objects with tremendous force. This is why all large construction equipment is operated hydraulically.

Many of us who have a basement in our homes have experienced or know someone who has experienced water coming into their basement area either through concrete walls or sump pump area. This usually happens after a heavy rain or down pour when a lot of water is dumped from the skies in a relatively short period of time or if it rains for days at a time and saturates the ground.

As the water filters down into the ground the weight of the water increases and forces its way into the path of least resistance which can be a sump area in the house or through the more porous openings of a concrete basement wall. The longer it rains the more water, the more water the more weight and the higher the hydrostatic pressure.

While many of the newer homes have drain tiles located around the parameter of the basement, many of the older homes do not. And even with drainage tiles many new homes with basements now have sump pump(s) to keep water from coming into the basement area. Water can even come in through small cracks or openings in the basement floor.

In many cases water problems in homes can be man made. If you have a lawn sprinkling system and many of the sprinkler heads are located close to the house, you can have water soaking the area close to the foundation and create the same problem. Or, if you don’t have any downspouts on your gutter systems or the downspouts don’t drain water far enough away from the home foundation, the same problems can occur.

Water can be one of the most destructive challenges to a home. Not only can it destroy carpeting and damage equipment on the basement floor, but the higher moisture levels and wet materials provide a perfect breeding ground for mold. Once you have experienced water in the basement it is essential that all affected areas are completely dried and all standing water removed.

In basements that are unfinished, normally the heating/cooling ductwork is not completed. Typically there is only one supply vent and no return vents constructed in the duct system. The system is only completed when the basement is finished as part of the initial construction. This is important to know for two reasons.

First, with no return air grills in the basement none of the airborne dust or mold particles or humidity will be drawn back to the HVAC system. This means none of the air will be filtered (assuming there is a filter or filtration system on the HVAC unit).

Second, none of the humidity will be removed from the cooling coils or dried through the heating system. This means you will have a higher moisture content in the basement than in the first and second stories of the home. Keeping water, water vapor and humidity out of the basement is essential to eliminate the possibility of mold growth.

Pure Air Systems manufactures a line of HEPA based air filtration systems that can be used either as stand alone units or attached to existing HVAC systems. The smaller, portable units can be used to filter the air in an area such as a basement and the larger units are designed as whole-house units. For more information on our complete product line or information on reduction/removal of airborne contaminants like mold, please go to our website at:

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Help! My Job Is Making Me Sick!

While many of us have often complained about our jobs, employers and co-workers being difficult to deal with, most people don’t associate their place of employment as the root cause for making them ill or sick.

Back in the 1980’s the term “sick building syndrome” was coined and it related to the fact that the indoor air quality in many commercial, institutional and industrial buildings was so poor that many of the employees developed allergies, respiratory issues and even asthma from long term indoor exposure.

After a lot of study it was determined that some of the main causes for the poor indoor air quality were lack of ventilation and/or amount of fresh air and the chemicals that were being off gassed from the building materials and office equipment. In addition, many of the office sections that were attached to  manufacturing sections were down wind of the contaminants being produced by the manufacturing processes.

Many employees sued their employers and building owners and managers and made the building and mechanical engineers aware that this IAQ problem was significant. As a result of the employee fire storm a number of changes were made by both ASHRAE ( American Society of Heating Refrigeration and Air-Conditioning Engineers) and BOMA (Building Owners and Managers Association) for new construction of buildings. These new changes; both in building materials and HVAC modifications, made some significant headway in maintaining a healthier, safer work environment.

Some of these changes included adding more outside air through the economizers located in the HVAC air handling units, better heating/cooling comfort level controls and better ventilation for office equipment such as printers, copiers and fax machines. These changes went a long way to making significant improvements in the work environment. Then came 9/11 followed by the current economic meltdown.

While these two events did not happen simultaneously, they both have negated many of the changes that were previously made to ensure better indoor air quality. 9/11 forced many building owners to reduce or eliminate the amount of fresh outside air introduced into the buildings. They were concerned with the possibility of terrorists using chemical or radiological gases and these gases being drawn into the building.

This change did two things. First, it reduced the amount fresh air and reduced air exchange rate. Secondly, because they were not bringing in cold or hot humid outside air, they found their heating and cooling bills were substantially lower. So in one case it increased the amount of CO2 in the work environment which brought back the IAQ problem but it did save them money.

This event was shortly followed by the slowdown in the economy and the current economic meltdown. With fewer employees in the office buildings and with more companies having significant cash flow issues, there was no need to go back to the modified ventilation rates and other IAQ positive practices. In addition, with the threat of losing a job a reality for many people, nobody is going to complain or sue their employee because of some indoor air quality problem.

Today, the problems with poor indoor air quality still exist and employees are still having some of the same issues that they had in the 80’s.

Pure Air Systems has been making fan powered HEPA based air filtration systems since 1985. From the beginning these units were designed to not only filter the air in a select area but also have the ability to introduce outside, filtered fresh air into a building with minimal affect on the heating or cooling costs. For more information on how these systems work and the complete product line please go to:

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