SCBA Negative Pressure Conversion - Inhalation and Exhalation Ported 40MM NATO (RD40x1/7) Threaded Coupler

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SCBA Positive Pressure Conversion - Inhalation and Exhalation Ported 40MM NATO (RD40x1/7) Threaded Coupler This is a prototype design intended to assist in converting positive pressure respirators, self-contained breathing apparatus (SCBA), into negative pressure CBRN masks. Due to the positive pressure nature of SCBAs, they typically do not feature inhalation or exhalation ports on the mask side, and the exhalation port is located on the oxygen quick disconnect regulator piece, such as on Avon, Scott, and Draeger SCBA respirators. This adapter provides the inhalation and exhalation ports/gaskets in a form of a coupler that bridges between the 40 NATO (RD40x1/7") threaded SCBA mask, or SCBA, and the filter step-down cartridge adapter. This ensures proper negative pressure backwards compatibility/functionality. This prevents fouling the back side of the filter cartridge, reducing humidity and the accumulation of concentrated carbon dioxide levels during prolonged respirator usage, which increases breathing comfort. Recommended due to the increased overall length (OAL) of this swiveling coupler, ability to clock the exhalation port separate from RD40 threads, operators use hose connection to PAPRs/SCBA breathing apparatus system, and wear filter cartridges on the belt line. Part Description: SCBA_NEGATIVE_PRESSURE_CONVERSION_EXHALATION_GASKET_GEN1.stl SCBA_NEGATIVE_PRESSURE_CONVERSION_EXHALATION_THREAD_GASKET_GEN1.stl SCBA_NEGATIVE_PRESSURE_CONVERSION_EXHALATION_THREADED_ASYM_GEN1.stl SCBA_NEGATIVE_PRESSURE_CONVERSION_EXHALATION_VALUE_COVER_GEN1.stl SCBA_NEGATIVE_PRESSURE_CONVERSION_INHALATION_EXHALATION_PORTED_RD40_COUPLER_MAIN_GEN1.stl SCBA_NEGATIVE_PRESSURE_CONVERSION_INHALATION_EXHALATION_PORTED_RD40_COUPLER_MAIN_THREADED_ENDS_GEN1.stl SCBA_NEGATIVE_PRESSURE_CONVERSION_INHALATION_GASKET_GEN1.stl SCBA_NEGATIVE_PRESSURE_CONVERSION_MAIN_REAR_THREAD_GASKET_GEN1.stl SCBA_NEGATIVE_PRESSURE_CONVERSION_RD40_COUPLER_MALE_SIDE_GEN1.stl SCBA_NEGATIVE_PRESSURE_CONVERSION_RD40_COUPLER_NUT_GASKET_GEN1.stl SCBA_NEGATIVE_PRESSURE_CONVERSION_RD40_COUPLER_NUT_GEN1.stl SCBA_NEGATIVE_PRESSURE_CONVERSION_RD40_GASKET_GEN1.stl SCBA_NEGATIVE_PRESSURE_CONVERSION_RD40_REAR_GASKET_GEN1.stl Initial model release. Disclaimers/Risks: 1.) Use Proper Gaskets Requires a number of gaskets due to the swiveling/ ability to clock the exhalation port separate from the RD40x1/7 threads. Please see the cross-sectional and exploded view diagrams for assembly cross-reference. 2.) Perform Proper Negative Pressure Test Follow SSPs established by your institution or workplace for further guidance. But in general, don your respirator, adjust straps till taught against face, ensuring no obstructions around the periphery of the seal against face either due to hair, facial hair, or otherwise. Exhale deeply. Cover all inhalation ports. (Typically, most full-face or half-face respirators have two filters, so cover those intake ports with your hands. If you are running only one filter, ensure the opposite port has a filter cap in place.) Now inhale deeply. The mask should suck tightly against your face without any air leakages. Re-test if adjustments are required at gasket/o-ring interfaces at the adapter. 3.) 3D Printing Materials Not Resistant to Many Solvents 3D printing materials are not resistant to many solvents, are water-soluble, and degrade when exposed to chemicals, heat, and UV/sunlight. 3D printing this adapter is only a temporarily ad-hoc solution against biological contagions. In addition to using a properly calibrated 3D printer, due to tolerances of adapters, if possible perform hot nozzle passes on all exterior surfaces, to reduce surface porosity. Highly recommended users apply a thin layer of polyurethane clear coat on all exterior surfaces, spray or dip based methods, to help resiliency and durability for repeated sterilization and to reduce fomite transmission in printed infill layers. Once supply chains return to normal, users should purchase OEM OSHA/NIOSH/EN standard-approved respirators, adapters, and accessories for their institution and workplaces. Dev. Notes: 5/11/2020 - Initial model release. In work, pending 3D printing community support for any fitment and model revisions. Credits: Thanks to Jack Pirone feedback and design suggestions regarding SCBA functionality.