Blog Post

Graphic Explanation of How N95 Respirators Actually Work

By | Blog Post

There is a lot of misinformation about the way N95 respirators work and in fact what the designation actually means. In order to understand the  AAC/CPC method of fit testing, it is really helpful to first understand the filtration mechanisms that occur in the Filtering Facepiece Respirators such as the N95 series.

We recently found this video, which does an excellent job of explaining the physics of the N95.

In fact, we were so impressed by the very straightforward explanation of the filtering mechanisms that we asked the production company for permission to link to the YouTube video, which they graciously granted.

The video contained in this link is meant for educational purposes only and was produced by ‘MinutePhysics’ who are solely responsible for its content and messaging. You will be redirected to the MinutePhysics YouTube Channel to view this very informative piece about the physics and performance characteristics of N95 respirators.

How Long is the SARS-CoV-2 (Coronavirus) Viable Outside an Infected Individual?

By | Blog Post

One of the many important things to know about the particular strain of coronavirus which is the etiological agent of the current pandemic is the length of time the virus can remain infectious when it is in the environment.

Yesterday (March 17, 2020) an exceptionally well written and documented letter was published in the New England journal of Medicine which can be found here:
and which gives some pretty clear answers which everyone should know.

Unfortunately, on relatively inert surfaces such as plastics and stainless steel the virus is sufficiently robust to have a half-life such that it probably is infectious up to 72 hours after deposition. Copper surfaces are more active, and the viability seems to be about 4 hours. What is most concerning (at least to me) is that apparently the virus can remain viable in aerosol droplets for up to 3 hours.

This is why healthcare workers who may be exposed to infected (and infectious) individuals should seriously consider respiratory protection.

We at AccuTec-IHS want to once again stress the fact that merely wearing a respirator (such as disposable N95’s, N99’s or N100’s) isn’t enough. The respirator must have been properly fit-tested. A
quantitative fit test such as the fit test performed by the AccuFIT 9000 can truly prove that the mask fits and that the person wearing it knows how to deploy it properly.

We at Accutec-IHS are monitoring the situation constantly, and are doing all we can to keep up with demand.

Questions or comments? Let us know at

The Difference Between CNC & CNP Fit Testing

By | Blog Post

Video Transcript

I understand that respirator fit testing is becoming more important all the time. It looks like there are two methods for performing quantitative fit testing, CNC and CNP. What’s the difference? You’re right. There are essentially two methods currently in use to perform quantitative fit testing of tight fitting respirators. First, the most widely used method is the ambient aerosol method using condensation nuclei, counting CNC, which can best be described as challenging the seal of the respirator with naturally occurring ultra fine particulates which mimic gas molecules due to their extremely low mass characteristics. And secondly, the controlled negative pressure or C N P method, which pulls a slight negative pressure inside the mask and then measures the exhaust to determine how much more air must be pumped out in order to maintain that same low pressure. Both methods sound pretty reasonable. Is one better than the other? Well, let’s look at some specifics.

The way the CNP system measures the pressure inside the respirator is by using a very sensitive pressure transducer. When the pressure rises, the system runs the vacuum pump and measures the amount of air in the exhaust, which is theoretically identical to the amount of air which is leaked past the respirator seal. So far so good. Whoa. If the pressure transducer is all that sensitive and the test subject is breathing, doesn’t that change the volume and pressure in the breathing zone? Well, yes, so the test subject has to hold his or her breath while the leak rate is measured. Furthermore, the test subject cannot move at all or the pressure will change slightly and the system will interpret that change as a leak. Wait a minute. Don’t people actually move and breathe when they are wearing respirators and if a person is wearing a respirator performing his or her job, aren’t they actually challenging the seal more than they would be when they are completely immobile?

Again? Yes. That’s why the exercises in the CNC protocol actually exist to challenge the seal in a dynamic manner. Obviously if you are moving and performing a workplace task, you are challenging the seal and the control negative pressure system doesn’t do this. Nope. The measurements are only made while the test subject is completely still and not breathing. Then why does the CNP protocol include these exercises? Good question. Probably so that the test will appear to actually be testing the fit while the subject is moving, but it actually doesn’t know well, how does the ambient aerosol method work? The system measures the concentration of ultra fine particulates in the ambient atmosphere and then measures the concentration of these ultra fines, which are also frequently referred to as respirable particulates in the breathing zone of the respirator. While the test subject is actually moving and breathing. Then this system measures the ambient concentration, again, computes an average of these two values and compares that value to the concentration inside the breathing zone.

The resulting ratio is the fit factor, which is a real measure of how well the respirator actually fits. Wow, so the important thing is that the actual measurements are performed while the test subject is moving and breathing, correct? Correct. Oh, wait a minute. How do these particulates get removed from the breathing zone? That’s one of the beautiful things about using ambient aerosols as a challenge agent. They are naturally absorbed by the lungs. That’s one reason they’re called respirable particulates. If the respirator being tested is set up with a HEPA filter in the inlet in about a minute, the concentration ACE and tonically approaches zero then any new particulates observed in the breathing zone penetrated past the respirator seal. What about the time it takes to perform a fit test? Isn’t the controlled negative pressure method quicker? Back in the day it was. However, there’s a new protocol which has been approved by OSHA, which allows a CNC test to be performed in less than three minutes. Well, what about filtering face pieces like in 90 fives or in one hundreds CNC works very well for filtering face pieces. CNP doesn’t. Why not? Have you ever tried to pull a vacuum on a disposable Mask.

How to Setup the AccuFIT9000 Fit Testing Machine

By | Blog Post, Tech Support

Video Transcript

Hi, I’m Wesley with Accutec-IHS. The AccuFIT9000 is a new instrument for performing respirator fit testing which depends on measuring the fit of a tight fitting respirator by comparing the ratio of the respirable particles in the breathing zone, with the concentration of these ultra-fine particles in the ambient atmosphere. This technology is called condensation particulate counting. To learn more, watch the video condensation particulate counting on the AccuFIT9000. 

          Let’s ensure the instrument is working properly, remove the instrument from the carrying case and locate the power supply AC cord, alcohol capsule sample tubing, and HEPA filter. Plug the power supply into an electric outlet. Connect the power supply and plug the connector into the port on the back panel of the AccuFIT9000. Next, remove the alcohol wick assembly from the capsule and place it on a clean surface. Then pour reagent grade isopropyl alcohol which is supplied with the instrument into the capsule so that the level of liquid is above the bottom line and below the top line. Replace the alcohol wick into the capsule and allow the alcohol to saturate the wick. This takes about two minutes. Remove the wick assembly from the capsule and tap off any excessive alcohol. Then remove the storage cap from the AccuFIT9000 alcohol port and replace it with the saturated alcohol wick. The locating pin and camming groove on the cap will guide the wick into its proper location. Now attach the sample tube to the a AccuFIT9000 making sure that you attach the blue tube to the blue inlet and the clear tube to the silver Inlet. Attach the HEPA filter to the clear tube making sure that the arrow showing flow direction is pointing toward the tube. Now press and hold the on/off button on the AccuFIT9000 until it illuminates with a red light. Allow the instrument to complete its warm-up and internal self checks. This takes about a minute and then will automatically transition to the opening screen.  The on/off button will now illuminate green. Touch the administration icon and then select the database icon using the drop down arrow. Highlight demo and then touch the load button. A message should appear telling you that the database demo is successfully loaded into active memory. Please note that the demo database does not allow you to perform all of the functions to test the instrument. It does not allow you to add names, respirators, or protocols to memory, nor does it allow you to save any results obtained. Press exit and then the return arrow on the previous screen. This returns you to the opening screen.

          Now it is time to test the functionality of the AccuFIT9000. Touch the icon labeled validation check, remove the HEPA filter from the clear tube and press start. The AccuFIT9000 will now measure the ambient particles and produce account. The validation check will now ask you to replace the HEPA filter into the clear tube and press next. The validation check will proceed automatically to check that there are no internal leaks in the system, that the switching valve is functioning properly, and that the unit can calculate the max fit factor. You have now demonstrated that the AccuFIT9000 is performing as designed. To shut down the instrument, hold the on/off button until it flashes red and green and touch the yes box. It is very important to remove the alcohol cartridge and replace it with the storage cap. Failure to remove the alcohol cartridge can result in alcohol contamination of the optics. Replace the alcohol cartridge into the   capsule. This ensures that there will be no spillage and that the alcohol cartridge will be ready to use the next time you want to perform fit testing. If the AccuFIT9000 is to be stored in the carrying case, remove the sample tube and power connector, and place the cutouts in the protective foam insert and position the instrument appropriately.

Protect Against the Coronavirus With Respirator Fit Testing

By | Blog Post

Both CDC (Centers for Disease Control) and WHO (World Health Organization) have now recognized the 2019-nCoV coronavirus outbreak as being serious. One of the more concerning developments is the fact that 2019-nCoV has shown to be capable of human-to-human transmission. This was first documented in this country today, January 30, 2020, in Chicago where a recently returned visitor from China has infected her husband.

Because of this demonstrated ability of the new virus to effect human-to-human transmission, CDC has issued guidelines for health professionals which can be accessed at the bottom of this page:

One of the recommendations the CDC Document mentions is the use of respiratory protection. Typically, healthcare facilities use N95 Filtering Facepieces (FFP’s) or powered air-purifying respirators (PAPR’s). PAPR’s need to be cleaned and disinfected after each use, while FFP’s are discarded after each exposure to airborne pathogens, so the chances are greater that N95 FFP’s will be the respiratory protection devices of choice.

AccuTec-IHS would like to remind users that it is imperative that fit testing in accordance with 29CFR 1910.134 be performed for each user of the tight-fitting respirators (in this case N95 FFP’s). From personal experience we can state that even though the techniques of donning, testing, and wearing an N95 FFP appear to be logical and straightforward, in reality if the user has not been adequately trained, the mask is worse than useless because it imparts a false sense of security to the wearer. This training should incorporate a Quantitative Fit Testing device where real-time and completely objective measurements can show the user graphic proof of protection while the mask is being adjusted to fit. (This real-time information is for training purposes and does not constitute a fit test.)

OSHA has recently approved a much faster Quantitative Fit Test protocol for the filtering facepieces (N95) which takes less than three minutes to perform. A legal Qualitative (i.e., subjective fit test) requires about twenty-three minutes. 

The AccuFIT9000 is capable of testing many of the commonly used N95 masks.

Please contact us to determine if the AccuFIT 9000 is suitable for your fit testing requirements.

New Quantitative Fit Testing Technology

By | Blog Post

Video Transcript

I am Connor O’Donnell, cofounder of Accutec-IHS. Our flagship product is the AccuFIT9000 quantitative respirator fit test instrument. Accutec-IHS was founded in 2016 with a mission to bring a fresh new respirator fit tester to market. Here’s why. For nearly 30 years, there were only two manufacturers capable of performing the OSHA fit test protocol. One was the controlled negative pressure method and the other was the condensation nuclei counting method. Our founders and consultants have over 75 years of combined respirator fit tester experience, so we knew early on that we would use the CNC method, which allows a respirator to be tested in a dynamic manner. Frankly, if a respirator is going to leak, it’s going to leak while you’re talking, breathing, moving your head and performing basic work functions, not while you’re holding your breath. To differentiate ourselves from our competition, we listened to the voice of the customer.

Because of this, we were able to build in some exciting new features, including standalone mode, built in wifi, and some unique programming, which allows us to be the first respirator fit test or on the market with wireless operator mode. Wireless operator mode allows a person to control one to four units with a tablet, with independent start and stop times while still relaying the instructions to the fit test subject on the builtin display on the instrument. It core value of Accutec is to achieve total customer satisfaction. We stand 110% behind our product and honestly strive to continuously improve. For example, the AccuFIT9000 carries an industry leading three year warranty. When you make a decision to buy an AccuFIT9000 you’re not only buying a great instrument, but you’re getting a partner in your respirator fit testing endeavor.