The Top 4 Considerations When Evaluating Portable Air Scrubbers

Airflow ratings can be very misleading: The cheapest units are often the most costly

When purchasing portable air scrubbers for use on restoration and/or mold remediation projects, there are many factors that should be considered in selecting the proper piece of equipment. Too many times airflow (or claimed airflow) and price are the only issues considered before a purchase.  All too often the contractor finds that the equipment does not meet their expectations or needs when it arrives. 

1. Ease of transport

This is one of the most important, yet most overlooked, aspects of portable air scrubbers. Scrubbers must constantly be moved from job to job and from location to location during a project. Some units are designed for one-person operation; others may require two people to move. Weight is very important, but so is weight distribution. Scrubbers that include a transport system for easy movement by one operator are safer and more cost-effective to operate. A stair climber is also a valuable feature when stairs are a factor. Size and weight should also be considered when thinking about transport and vehicle requirements.

2. Air scrubber filtration system

The filtration system is the heart of a portable air scrubber. Poorly designed filtration can add hundreds or even thousands of dollars in annual operating costs. Filters must provide a substantial dirt-holding capacity and long filter life without significant airflow loss. A well-designed filtration system requires three stages of filters to progressively filter all particle sizes. If odors and particulates are to be removed simultaneously, a fourth stage of gas/odor filtration may also be needed.

Easy “no tools” access is important when inspecting and replacing dirty filters. The filter module should not have to be removed to change or inspect filters. This is time consuming and can also cause debris to be spilled onto the HEPA and the surrounding area.

HEPA filters must be individually tested by the filter manufacturer and certified to a minimum efficiency of 99.97% at 0.3 microns. It is not enough to simply assemble a filter using HEPA media. A true HEPA filter must be constructed to the exact manufacturing practices necessary to ensure that the finished filter does not leak through the filter media or around the frame or seams. If debris can bypass the HEPA media, the filter will not pass DOP testing required in many abatement specifications. Insist that the HEPA filter itself be certified to HEPA standards, with a certification label affixed to the frame of the HEPA filter.

3. Blower type

Air scrubbers are required to trap large quantities of debris. Debris buildup on the filters hinders the airflow and causes what is technically known as static resistance. Specific blowers are much better suited than others for overcoming this resistance. There are many types of air moving blowers available, each with specific characteristics for certain applications. 

For example, forward-inclined “squirrel cage” blowers are designed to move large volumes of relatively clean air and low static resistance. These inexpensive blowers may be suitable for applications such as use in a furnace or even in an asbestos negative air machine; they are not, however, a very good selection for use in an air scrubber.

Backward-inclined or airfoil type blowers are a much better choice since they are engineered with the capacity to overcome the pressure drop of dirty filters. The use of this type of blower will not only increase filter life but will also produce higher airflow as the filters begin to accumulate debris. This generally means significantly better performance (airflow) over the life of the filters and much lower replacement filter expenses than a scrubber or negative air machine that is equipped with a forward inclined blower with a comparable peak airflow rating.

4. Materials and construction methods

Most negative air machines position the blower at the outlet of the cabinet, and pull air through the cabinet. This keeps the entire cabinet – including the section downstream from the HEPA filter - under lower (negative) pressure compared to the air in the surrounding area. With this design, the machine must be perfectly sealed to prevent contaminated air from being sucked into the cabinet and exhausted without ever passing through the HEPA.

This is a big concern when the unit is used as a negative air machine and exhausts air into another part of the facility, especially if that area is occupied. Any such leaks will negate the effectiveness of the HEPA filter and will more than likely cause contamination of the area and failure of any air testing required by the job specification. This should be an important liability concern of any mold abatement contractor.

Generally, the use of  gaskets and solid rivets produce the most leak free cabinets. Beware of any cabinet that uses fasteners such as hollow pop rivets, or threaded fasteners such as sheet metal screws or nuts and bolts. These devices do not afford the airtight seal necessary to keep small particles from infiltrating a negative pressure cabinet.

Fun fact: It has been found that sub-micron particles can actually travel along the threads of a screw or bolt!

Lastly, make certain that any hardware, instruments, or transport system components that penetrate into the cabinet are sealed in such a way as to prevent any leakage or bypass. For more information on evaluating portable air scrubbers contact us!

7 FAQ’s About Asbestos Abatement Equipment

7 FAQ's About Asbestos Abatement Equipment

Frequently asked questions about HEPA-AIRE® Negative Air Machines for asbestos abatement.

Does the machine actually produce the airflow you think you’re getting?

One of the most confusing, inaccurate and potentially misleading methods of testing this is ‘free air’, which is nothing more than the test bench rating of the blower. The airflow produced by the device will be up to 60% lower when the blower is enclosed in a cabinet and must pull air through the resistance of the filters.

The airflow comparison chart shows that the true airflow of negative air machines can vary substantially from brand-to-brand because different suppliers use different rating methods and components. Click here to view the chart.

Does the HEPA filter truly provide 99.97% HEPA filtration?

A filter made with HEPA media may or may not provide true HEPA efficiency. Serious leakage can go undetected if filters are not individually tested and certified at the end of the manufacturing process in accordance with IEST-RP-CC001.3 guidelines for Type A HEPA filters. Even the tiniest pinhole leaks in the media or breach of the seal between the media pack and the filter frame can cause the filter to fail efficiency requirements. If this happens, contaminated air can pass through the filter and be exhausted into ‘clean’ areas of the facility.

HEPA testing requires very specific procedures using a thermally generated mono-dispersed aerosol and a laser particle counter. Test results, including test airflow, percent penetration, date of manufacture and other detailed information must be included on a label affixed to the filter. Testing should be conducted at the rated airflow of the machine. A filter designed for and tested at 1,000 cfm or 1,100 cfm may provide significantly lower efficiency at 2,000 cfm. If the filter label simply states “99.97% HEPA Filter” or “2,000 CFM HEPA Filter”, but does not include all of the detailed testing information, it’s probable that the filter has not been individually tested.

Is the machine designed to prevent bypass leakage around the HEPA filter?

Even the best HEPA filter can’t prevent contamination problems if the machine is not designed to prevent contaminated air from bypassing the filter. Look for important contaminated air bypass prevention features such as:

• Flat, rigid HEPA sealing frames with no welds or other surface irregularities that can disrupt the seal

• Seamless poured closed-cell neoprene gaskets or silicone gel seals as opposed to gaskets with seams or made from open cell foam

• Solid rivet fasteners versus weaker and potentially leaky hollow pop-rivets or metal screws.

• Sealed control panels

Is the machine safe?

Why take the chance on an untested and potentially unsafe machine? OSHA (U.S.) and CSA (Canada) require electrical safety testing and certification by an approved Nationally Recognized Testing Laboratory (NRTL), such as UL, CSA or ETL. This overall testing is required even if the individual electrical components are all NRTL listed.

Contractors may be surprised to learn that the HEPA-AIRE® Negative Air Machines manufactured by Abatement Technologies® are currently one of the few brands that meets these requirements. All Abatement Technologies negative air machine models are certified by a Nationally Recognized Testing Laboratory (NRTL)., and carry their ETL/ETLC mark for safe operation on 115V/15A electrical supplies.

What makes HEPA filters so efficient?

The ultra-fine, glass-fiber medium captures microscopic particles that can easily pass through other filters by a combination of diffusion, interception and inertial impaction. To qualify as a Type A HEPA filter, the filter must capture at least 99.97% of particles 0.3 microns in size–about 300 times smaller than the diameter of a human hair, and 25 to 50 times smaller than we can see.  To a HEPA filter, catching a one-micron particle is like stopping a cotton ball with a door screen.

Why is the testing done with a 0.3-micron particle size test aerosol?

Filter efficiency studies have shown that 0.3-microns is the "Most Penetrating Particle Size (MPPS)" for HEPA filter media. Efficiency is typically greater than 99.97% against larger or smaller particle sizes. Particles larger than 0.3 microns are typically more easily trapped, or intercepted, by the media. Smaller particles often lack sufficient mass to penetrate the media.

Does HEPA efficiency decrease as the filter gets dirty?

No. The dirtier a HEPA filter gets, the more efficient it typically becomes.

Have another question? Contact us

The Best Ways to Enhance Whole-Home Air Purification

Learn about the best ways to enhance whole-home air purification

Clean purified air is desired more than ever, especially in our homes. Harmful particles and pathogens can pose a risk on our short and long term health. There is advanced purification technology that exists and is created with the intention of trying to improve whole-home air quality. Allergists and other medical professionals widely promote allergen avoidance as a way to improve health of sensitive individuals with respiratory diseases.

 

The premise is simple, reduce exposure to pollutants. Central Air Purification (CAP®) units from Abatement Technologies incorporate one or more effective and targeted air purification technologies for this purpose.

 

Mechanical particle filtration

 

Filters are assigned a minimum efficiency reporting value (MERV) rating between 1-16, the higher the rating the better the filter is at removing small particulates. A standard low-efficiency throwaway furnace filter rated at MERV1 or MERV2 is only effective for large particles.

 

CAP®100, CAP®600 and CAP®1200 series HEPA Air Purification Systems are equipped with MERV 4 first stage pre filters designed primarily to capture large, visible dirt and dust particles that are too large and heavy to be respirable, but can become a housekeeping issue when they accumulate on surfaces. The second stage pleated particle filters in these CAP® models capture smaller, visible particles that can easily pass through most throwaway furnace filters. The high-capacity 5” deep CAP®100 series second stage filter, MERV 13 is especially effective. 

 

Activated carbon filtration

 

The VAPOR-LOCK® activated carbon filters utilized in CAP®600 Series and CAP®1200 Series models capture airborne gasses, volatile organic compounds off-gassed from carpets, composite wood furniture and other materials in the home, and odors caused by pets, cooking or smoking. VAPOR-LOCK® filters utilize a process known as adsorption, in which the gas-phase molecules of the contaminants are attracted to and chemically bond to the surface of the carbon. 

Combining UV Germicidal Irradiation and Photolysis Technologies

Over time our homes endure different issues like persistent molds and fungal odor problems usually found in areas with high moisture or humidity levels like the damp, dark and dirty recesses of an HVAC system where organisms can thrive and multiply.

CAP® systems are equipped with our advanced, dual frequency UV plus lamp. Frequency one creates germicidal UV energy to irradiate and break down molds and fungi. The second frequency creates a controlled amount of trivalent oxygen for enhanced odor-neutralizing capability

CAP®100, CAP®500, CAP®600 and CAP®1200 Series Whole-Home Central Air Purifiers are equipped with germicidal UV lamp technology. Microorganisms are irradiated to high levels of UVGI energy each time they pass by the lamp as the air cycles through the central HVAC system of your home. All CAP® germicidal UV lamps are ozone-free. 

HEPA Filtration

The beauty of a HEPA filter is that its efficiency starts at 99.97% and actually improves as the filter loads. Because of the exceptional small-particle capture performance of CAP®600 Series and CAP®1200 Series models, these units are the most widely recommended for homes with family members who are asthmatic or have the highest sensitivity to respiratory allergens. 

To learn more about whole-home air purification and best practices, contact our knowledgeable sales consultants here.

Things To Consider Before Comparing Airflow Ratings

 

Things to Consider Before Comparing Airflow Ratings

Why airflow ratings can be very misleading and the cheapest units are often the most costly.

No industry-standard airflow rating method

There is no standardized method that manufacturers use to rate the airflow of their air filtration devices. Different methods can produce widely varying and often misleading results, and make direct comparisons between brands difficult if not impossible.

Compare ‘Apples & Oranges’

The most overstated and inaccurate method used bases device airflow ratings on the AMCA “free air” blower rating, which is a test bench measurement of the airflow the blower can produce at various motor horsepower levels with no static resistance. Since actual peak airflow with the cabinet and filters in place is typically 50% to 80% lower, free air is essentially meaningless when it comes to rating the device itself.

Inlet or outlet readings with an air-straightening duct attached to reduce turbulence are far more accurate. This testing is generally done using a computing vane anemometer or pitot tube traverse to determine the average velocity (in feet per minute) and airflow (in cubic feet per minute) flowing through the air straightening duct. Attempting to measure airflow at non-laminar inlet and outlet openings is not recommended.

Peak airflow is only part of the story

Even when accurate, peak airflows can be misleading because they provide only a small part of the performance picture. It's often a mistake to automatically conclude that the performances of two devices are equal just because their peak airflows are similar. The airflow of all filtration devices drop off as resistance to airflow increases due to filter loading, external collars or flex duct. The magnitude and frequency of these losses; and therefore how frequently filters must be replaced to restore acceptable airflow levels can vary greatly.

Peak static capacity of the blower and filter dirt holding capacity are the main factors that determine 'real life' airflow and filter life. As a rule, a backward curved blower can move more air than a cheaper but less efficient squirrel-cage blower, due largely to its ability to operate at much higher 'tip speeds' and therefore overcome higher levels of resistance. This higher capacity, in turn, extends the useful life of the filters and can make a higher price but more efficient system far less costly to operate.

Build in a sufficient margin of safety

To compensate for airflow losses, users should build in a safety margin when estimating how many units are required to provide a given number of ACH (air changes per hour). If the objective is 6 ACH, designing for 8 or 9 ACH at peak airflow should be more than adequate to ensure sufficient airflow throughout the filter loading cycle provided that the peak airflow rating is reasonably accurate.

See which, and how many units you would need for the appropriate amount of air changes per hour based on your room size with our Air Change Calculator

Contact us for more information!

 

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