Quantitative Fit Test (QNFT)
Safeopedia Explains Quantitative Fit Test (QNFT)The advantages of QNFT are that there is no limit of protection-factor, numerical results can be documented and there is no chance of user deception. The disadvantages are that it requires expensive equipment, a probe adapter and regular calibration.
During the test, a challenge agent is administered outside the face piece and the presence of the agent is detected and counted by an instrument.
There are three types of QNFT:
- Generated Aerosol: Uses corn oil and a photometer-based aerosol detector.
- Ambient Aerosol Nuclei Count: Uses laser technology to measure aerosol concentration inside and outside the respirator.
- Controlled Negative Pressure: Creates a vacuum in the mask and calculates airflow.
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