I don't understand the fit checks. Both, positive and negative say that "a good face seal has been obtained." One presents exhaling and the other inhaling. Is the inhaling a wrong fit check?
Wherever there is a danger of suffocation or other breathing hazards, it is mandatory to use a respirator. Also, wear a respirator when working with or near asbestos or where hazardous molds are growing.
This unit covers three types of respirators: air-purifying respirators, supplied-air respirators, and self-contained breathing apparatus.
Air-purifying respirators provide the lowest level of protection. They are made for use only in atmospheres that have enough oxygen to sustain life (at least 19.5 percent).
Air-purifying respirators are chemical-specific. They use special filters and cartridge to remove specific gases, vapors, and particles from the air.
The respirator cartridges contain charcoal, which absorbs certain toxic or deadly vapors and gases.
When the wearer detects any taste or smells indicating the charcoal’s absorption capacity has been reached, it means the cartridge can no longer remove the contaminants.
Air-purifying respirators should be used for protection against only those types of contaminants listed on the filters and cartridges.
Supplied-air respirators provide protection for extended periods. A high-pressure hose is connected to an external source of air, such as a compressor, compressed air cylinder, or pump.
Supplied-air respirators are typically used in toxic atmospheres. They provide protection in atmospheres where air-purifying respirators are not adequate.
Self-Contained Breathing Apparatus
Self-contained breathing apparatus (SCBAs) provide the highest level of respiratory protection.
They can be used in oxygen-deficient atmospheres (below 19.5 percent oxygen), in poorly ventilated or confined spaces, and in IDLH (Immediately Dangerous to Life or Health) atmospheres.
More Information on Respirators
A respirator must be selected based on the contaminant present and its concentration level.
• When selecting a respirator to wear while working with specific materials, first determine the hazardous ingredients in the material and their exposure levels.
• Always read the material safety data sheet (MSDS), which is often located in a binder in the project manager’s or supervisor’s office.
Respirators - Positive and Negative Fit Checks
All respirators are useless unless properly fit-tested to each individual.
To obtain the best protection from a respirator, perform positive and negative fit checks each time you wear it. These fit checks must be done until you obtain a good face mask.
The next slide presents the steps that need to be taken to perform positive and negative fit checks on respirators.
Click on each term to find out more about the steps involved in performing fit checks for respirators:
Positive Fit Check
1. Adjust the face piece for the best fit; then adjust the head and neck straps to endure good fit and comfort.
2. Block the exhalation valve with your hand or other material. Breathe out into the mask.
3. Check for air leakage around the edges of the face piece. If the face piece puffs out slightly for a few seconds, a good face seal has been obtained.
Negative Fit Check
1. Block the inhalation valve with your hand or other material. Attempt to inhale.
2. Check for air leakage around the edge of the face piece. If the face piece caves in slightly for a few seconds, a good face seal has been obtained.
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