CNP Testing:


Why is CNP technology superior to traditional Ambient Aerosol fit testing?

Let Me See How It Works!

// Procedure

How it Works

One tube pulls a negative pressure, and to keep the pressure constant, it has to pull out any additional air that leaks into the respirator. This measurement directly tells us how much air has leaked into the mask, and that leak amount is converted to a fit factor.



You can complete our OSHA-approved Controlled Negative Pressure (CNP) Redon protocol in under two minutes. You’ll know if a user has a basic fit in 10 seconds. It’s that easy. Quantifit uses no consumables and is not environmentally dependent. In fact, it uses air as the challenge agent. 


More durable, more portable.

Quantifit provides the most accurate and verifiable fit test for respirators on the market, ensuring that your respirator fit properly. We designed Quantifit for durability and portability. It is now more streamlined and lighter than previous models and includes a carrying case, keyboard, onboard memory, and PC connections.

// Testimonials

What Our Clients Says

Emilia Clarke
Former Chief Robert Anthony
Chicago Fire Department
“The Chicago Fire Department implemented the OHD Quantifit for NFPA compliant SCBA fit testing. The Quantifit has increased our speed, accuracy, and ability to manage reports using OHD's FitTrack Gold software.”
Emilia Clarke
Dawn Bolstad-Johnson
"The best technology that I have found is the OHD Fit Tester. This method uses controlled negative pressure to actually quantify the size of the leak (if any) in the mask. Using air pressure as the challenge agent in fit testing gives the most accurate results and there are published scientific studies to prove it. Other quantitative methods may provide the user with a false positive or a PASS on the fit test. There is minimal chance for a false PASS result on the OHD fit tester because the air pressure inside the mask is what is being quantified. If there is a leak, it will be detected. Leaks matter even the small ones! The OHD Fit tester does not lie! Many Fire Departments have been using this technology for years."
Emilia Clarke
Matthew Fleming
Philadelphia Counter Terrorism Operations
“The OHD Quantifit provides us with confidence and will help protect Philadelphia Police offers in the line of duty. We are able to efficiently and quickly fit test our personnel with the most accurate fit test available (Quantifit). This has made the Quantifit a great addition to our respiratory protection program.”
Emilia Clarke
Bruce Donato
CSP, CHMM, CECD (K&A First Aid and Safety, Inc.)
“All, I wanted to say how impressed I am with your Quantifit. I have used your competitor’s product before and in comparison your system is so simple. I also was impressed that I could not get it to pass a fit test with my beard on, whereas I could do that with other quantitative fit testers. Excellent job.”

Fit Testing Demo

This video highlights the key benefits of utilizing the OHD Quantifit and our patented Controlled Negative Pressure (CNP) Technology to perform a TWO minute OSHA, NFPA and ISO approved Fit Test.