1. Part 2 – Supplied-air Respirators
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In Part 1 you learned about air-purifying respirators. Today we are going to cover supplied-air respirators. ▼

2. Supplied-air Respirators
Provide clean air from a source
Supplied-air respirators - often referred to as “fresh-air systems” - provide clean air from a source.
These respirators may have tight-fitting or loose-fitting facepieces. Most supplied-air respirators used in collision shops operate at positive pressure. This means that air flows OUT of the facepiece. ▼
As shown in this photo, the tight-fitting mask has a special connector that allows compressed air to be delivered directly to the user. When the connector is removed, cartridges can be attached and the respirator becomes an air-purifying respirator.
Tight-fitting full facepieces cannot be worn with regular glasses. ▼ A special adaptor that mounts inside the mask is needed. ▼
Loose-fitting hoods or helmets can be worn with prescription glasses without any difficulty. ▼
Tight-fitting
Loose-fitting

3. Supplied-air Respirator Components
hood
air filters
compressor
CO monitor
A supplied-air respirator has the following components: ▼
a compressor draws air directly from outside or an uncontaminated part of the shop - such as the office area. ▼
Air filters – that remove impurities, water, and oil. The air delivered to the respirator user must meet the “grade D” air purity requirements set by OSHA.
Depending on the compressor model, additional air filters may be needed. ▼
These can be mounted on the wall or may be housed in portable cases. A single filter - whether mounted on the wall or on a belt - can NEVER deliver air of Grade D purity. ▼
Other components of the system are:
a carbon monoxide (CO) monitor and alarm ▼
Air hoses from the compressor to the hood ▼
And a hood or another type of facepiece ▼
air hoses

4. SATA Vision 2000 Replace filters when +/-15 psi
Replace at fixed time intervals
Let’s look at the filtration system and the carbon monoxide monitor of the SATA Vision 2000, used at St. Cloud Tech.
Shown here is the 3-stage filtration system providing grade D air quality. Let’s look at each filter: ▼
Stage 1 – removes all particles with diameter greater than 5 microns; separates water and oil and removes water by condensation ▼
Stage 2 – removes all particles with diameters between 0.01 and 5 microns ▼
Stage 3 – activated charcoal – removes oil vapors and any other vapors that may be present. ▼
Stages 1 and 2 must be serviced when the pressure difference between the gauges is 15 psi. ▼
The charcoal filter, stage 3, needs to be replaced at fixed time intervals. ▼
Because carbon monoxide is NEVER removed from the air stream, it is very important that that a CO monitor is present and works properly. The CO monitor must be calibrated periodically using a calibration kit.
Remember: At school, we (the instructors) ensure that equipment is maintained and properly functioning. However once you graduate, YOU may be the only person in charge of this system in a shop! Know where to find the information you need to keep your fresh air system working FOR YOU. ▼
Stage 1
Stage 2
Stage 3

5. 3M Dual Airline Front-Mounted Breathing Tube Half-face Respirator
Half-face mask
Front mounting breathing tube
Supplied air hose
Air purification panel
Pressure regulator
Brooklyn Park campus of Hennepin Tech uses the 3M dual Airline Front-Mounted Breathing Tube, half-face respirator assembly.
BP-HTC:
- indicate on this chart the specific components used in your shop.
- add information related to filter change frequency and CO monitor testing & calibration.
Other instructors: read only the information below:
The parts of this assembly are as follows:
Half-face mask - Even though this system operates in positive-pressure mode, you still have to perform a user seal-check after putting the mask on.
Front-mounting breathing tube
Supplied air hose
Air purification panel
Pressure regulator
Remember: At school, we ensure that equipment is maintained and functions properly. However once you graduate, YOU may be the only person in charge of this system in your shop! Know where to find the information you need to keep your fresh air system working FOR YOU. ▼

6. Maintenance Change filters on time Calibrate and test the CO monitor
Inspect all respirator parts before use!
Periodic maintenance of the components of the supplied-air system is critical. ▼
Change filters on time. All manufacturers provide information about how often to change the filters. Delays in changing the filters can put your health at risk. ▼
Calibrate and test the carbon monoxide monitor periodically. Manufacturers provide test kits and instructions on how to do this. Carbon monoxide is NEVER removed from the air stream and you cannot tell when you are exposed. ▼
Inspect all respirator parts before use! Check the air hoses for holes or cracks and inspect the hood for any punctures or tears. Ensure that the carbon monoxide monitor is plugged in, and all filters are in working condition before you use the respirator. ▼

7. If/Then scenarios If you use a respirator and:
Smell or taste chemicals
Feel dizzy or lightheaded
Can’t breathe properly
Exit the contaminated area
Check respirator parts
Check all fittings and connections
Check the CO monitor
If you use a respirator and:
smell or taste chemicals,
feel dizzy or lightheaded,
or can’t breathe properly ▼
Stop what you’re doing and: ▼
Exit the contaminated area, remove your respirator, and go to an area with clean air.
Check respirator parts – verify all components are present and in good condition.
Check all fittings and connections – be sure that air hose connections are secure.
Check the CO monitor – if the alarm went on, try to find the source of carbon monoxide. It may be a vehicle idling by the air intake of the compressor. Reset the alarm.
Once you are sure that your respirator is in good working condition, put it on and return to work. Perform a user seal check if you wear a tight-fitting facepiece! ▼
See a doctor if the health symptoms persist even though your respirator is in good condition. Tell the doctor you work isocyanates and you wear a respirator. ▼
See a doctor if health symptoms persist!

8. Summary Always use a respirator when spray painting
Follow manufacturer’s instructions
See a doctor if you believe you have symptoms related to isocyanates or respirator use
In summary: ▼
Always use a respirator when spraying isocyanate-containing products. ▼
Follow manufacturer’s instructions for use and maintenance of all components of your supplied-air system. Change the air filters as recommended, and ensure that the CO monitor is calibrated and works properly. ▼
See a doctor if you experience symptoms related to your work with isocyanates or due to using respirators.▼

9. Questions?
Do you have any questions? ▼

10. End of Part 2 Supplied-air Respirators
This is the end of the module on Respirators.