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. 2020 Oct:8:e00129.
doi: 10.1016/j.ohx.2020.e00129. Epub 2020 Jul 27.

Conversion of self-contained breathing apparatus mask to open source powered air-purifying particulate respirator for fire fighter COVID-19 response

Benjamin R Hubbard  1 , Joshua M Pearce  2   3   4   5
Affiliations

Conversion of self-contained breathing apparatus mask to open source powered air-purifying particulate respirator for fire fighter COVID-19 response

Benjamin R Hubbard et al. HardwareX. 2020 Oct.

Erratum in

Abstract

To assist firefighters and other first responders to use their existing equipment for respiration during the COVID-19 pandemic without using single-use, low-supply, masks, this study outlines an open source kit to convert a 3M-manufactured Scott Safety self-contained breathing apparatus (SCBA) into a powered air-purifying particulate respirator (PAPR). The open source PAPR can be fabricated with a low-cost 3-D printer and widely available components for less than $150, replacing commercial conversion kits saving 85% or full-fledged proprietary PAPRs saving over 90%. The parametric designs allow for adaptation to other core components and can be custom fit specifically to fire-fighter equipment, including their suspenders. The open source PAPR has controllable air flow and its design enables breathing even if the fan is disconnected or if the battery dies. The open source PAPR was tested for air flow as a function of battery life and was found to meet NIOSH air flow requirements for 4 h, which is 300% over expected regular use.

Keywords: 3-D printing; Additive manufacturing; COVID-19; Medical hardware; Open hardware; PAPR; Personal protective equipment; Powered Air-Purifying Respirator; RepRap; Safety equipment.

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Conflict of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

None
Graphical abstract
Fig. 1
Fig. 1
Fully assembled open source PAPR a) all components and b) in use.
Fig. 2
Fig. 2
Housing Top (a, b) Before cleanup; (c) After cleanup (d, e, f) Design details.
Fig. 3
Fig. 3
Housing Bottom (a, b) Before cleanup; (c) After cleanup (d, e) Design details.
Fig. 4
Fig. 4
Pre-filter cover.
Fig. 5
Fig. 5
Respirator (a) Before cleanup; (b, c) After cleanup with design details.
Fig. 6
Fig. 6
Controller Case (a, b) with design details.
Fig. 7
Fig. 7
Suspender Clips (a, b) with design details.
Fig. 8
Fig. 8
(a) Cut and strip fan wires. (b) glue the fan wires in place.
Fig. 9
Fig. 9
12 V DC connector (a) provided with the battery; (b) cut off and prepare a male connector. The remaining connectors are not used.
Fig. 10
Fig. 10
Controller cables; cut to length, stripped, and marked.
Fig. 11
Fig. 11
(a) Cut duct tape to length (b, c) apply to HEPA filter.
Fig. 12
Fig. 12
Pre-filter (a) HEPA pre-filter; (b) surgical mask.
Fig. 13
Fig. 13
Weather-seal gasket, cut in half lengthwise.
Fig. 14
Fig. 14
3 M Cool-Flow Exhalation Valve removed from mask.
Fig. 15
Fig. 15
Gasket applied to the respirator.
Fig. 16
Fig. 16
Glued 3 M Cool-Flow exhalation valve in place.
Fig. 17
Fig. 17
Apply tape to the nozzle to provide and air-tight fit to the hose.
Fig. 18
Fig. 18
Glued wires in place in case.
Fig. 19
Fig. 19
Glued fan in place (if necessary).
Fig. 20
Fig. 20
Properly run wire management.
Fig. 21
Fig. 21
Wire joining (a) form hooks; (b) solder; (c) wrap and glue.
Fig. 22
Fig. 22
HEPA filter installation (a) engage gasket; (b) compress gasket; (c, d) slide into place.
Fig. 23
Fig. 23
Connect the wires to the controller.
Fig. 24
Fig. 24
Fix the PCB into the controller case.
Fig. 25
Fig. 25
Strain-relief for the wires and attached knob.
Fig. 26
Fig. 26
Apply gasket to the perimeter of the housing bottom.
Fig. 27
Fig. 27
Use the screw to secure the housing together.
Fig. 28
Fig. 28
The battery is inserted.
Fig. 29
Fig. 29
The controller is connected to the battery.
Fig. 30
Fig. 30
Pre-filter installation (a) fit into cover; (b) install on housing.
Fig. 31
Fig. 31
Donning Steps.
Fig. 32
Fig. 32
Use tabs to remove HEPA filter.
Fig. 33
Fig. 33
Airflow testing bag.
Fig. 34
Fig. 34
The airflow test setup, mid-test.
Fig. 35
Fig. 35
PAPR airflow test results.
Fig. 36
Fig. 36
Battery voltage as a function of run time with no pre-filter and with a surgical mask prefilter.
Fig. 37
Fig. 37
Battery life indicator lights.
See this image and copyright information in PMC

References

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