Wildland respirator

Abstract

A breathing apparatus, primarily for wildland firefighters, that is low-weight, low-volume, non-encumbering, and operable for at least 4 hours. The breathing apparatus comprises a mask adapted to surround the mouth or nostrils of a user, a non-encumbering filtration component with a flow generator, and an air channel attaching the filtration component to the mask. The filtration component attaches to a WLFF backpack and does not impede the user's back of neck, lower lumbar, or chest area. The filtration component is preferably located in a storage pouch with a ventilated bottom. The flow generator filters air from a surrounding environment with a battery power supply, controls air pressure to the mask, and adjusts power usage based on a measured pressure to the mask. Also, a method for using a breathing apparatus, providing a constant airflow to the mask of 115 Lpm and executing a battery-preserving algorithm to adjust the blower power.

Description

Wildland RespiratorRELATED APPLICATIONS

[0001] The present application claims the benefit of provisional application number 63 / 535,210 filed August 29, 2023 (by Girish Srinivas, Drew Galloway, Nathan Weinstein, and Grant Bracht, attorney docket number 20-11), which is incorporated by reference herein. The present application also claims the benefit of provisional application number 63 / 687,273 filed August 26, 2024 (by Girish Srinivas, Andrew Davis Galloway, Nathan Weinstein, Grant Bracht, and Cameron Miller), which is also incorporated by reference herein.STATEMENT OF GOVERNMENT INTEREST

[0002] This invention was made in part using U.S. government funding under contract No. 18SFTRG00004-01-00 awarded by the U. S. Department of Homeland Security. The government has certain rights in this invention.FIELD OF THE INVENTION

[0003] The present disclosure generally relates to a breathing apparatus, and in particular to a portable powered air purifying respirator. The present disclosure also relates to a respirator mask and a respirator system that has a low-weight, low-volume design, which does not inhibit the user, which is nonencumbering due to its compact construction and mounting away from the user's neck, lower lumbar, and chest area, and which is effective and efficient to operate in wildland firefighting applications for a minimum of 4 hours.BACKGROUND

[0004] Powered air-purifying respirators (PAPRs) use power to draw surrounding air through filters, pressurize it, and transfer filtered air to users via conduits to airway sealing masks. PAPRs are utilized for heavily polluted industrial environments where the air can be filtered to produce acceptable breathingair. They create a positive-pressure air supply, which forces the polluted surrounding atmosphere away from the user's airway.

[0005] Historically, manufacturers of Personal Protective Equipment (PPE) designed PAPRs for shiftlength or multi-hour use in heavily polluted industrial environments. Using PAPRs close to where their consumables (replacement batteries or filters) are stored allows users to stay on task. However, industrial PAPRs are usually too heavy or oversized to be attractive options for long-distance hiking or hard physical labor. Industrial PAPRs are unable to operate for long periods of time on portable power without being excessively heavy.

[0006] Wildland firefighters (WLFFs) commonly work in smoke after hiking several miles. The risk posed to their health by smoke constituents from wildfire is unacceptable, as defined by occupational health and safety organizations. Existing respiratory protective devices are not able to meet the specific needs of wildland firefighters (low weight, small size, non-encumbering, able to operate for 4 hours without recharge).

[0007] In the USA, WLFFs must wear a standard backpack containing a fire shelter in an accessible pocket, with the remaining backpack volume used to carry water, food, tools, first air supplies, and extra clothing. The weight of the backpack and gear, like hoses, can be up to 80 lbs. They also must wear impactprotecting hats to protect themselves from falling debris, and often must carry hand tools that rest on their shoulders while walking to the next work site. Since WLFFs work in areas without roads, their legs must remain unencumbered to retain their ability to handle unstable and uneven footing. If they need to escape from an oncoming wall of flame, they do so without the aid of vehicles by walking quickly or even trotting to a safer space within their deployment area. Overall, nothing can be attacked to a WLFFs' legs, the backpack covers the back, and protective helmets cover the head. WLFFs wear long-sleeved, fire- resistant shirts and pants while performing hand work and wearing heavy backpacks, so their level of exertion is high. Areas on their bodies that can exhaust heat, like their faces and necks, must be unencumbered to provide evaporative cooling and prevent overheating and Heat Exhaustion.

[0008] A respiratory protection device for WLFFs that can produce safe, breathable air from polluted, smokey air without negatively impacting their ability to move and work quickly is needed. A respiratory protection device that inhibits their ability to perform strenuous labor activities and defensive measures would pose a new risk to their health or their lives and is unacceptable. A low-weight respiratory protection device that does not encumber the head, shoulders, back, legs, back of neck, or torso is needed.

[0009] US 2015 / 0314144 A 1 (Virr et al., Nov. 5, 2015) teaches an apparatus with a breathing mask and a neck component. The apparatus is a "low profile" PAPR, which has a "neck component," including a flow generator and filter "adapted to "substantially surround the back of the neck of the user." This PAPR requires a neck-encircling filter unit, which is encumbering to WLFFs. A device on the back of the neck causes additional heat retention and prevents WLFFs from dosing a rag in water and cooling themselves. Having a device of that weight and size on their neck is also a physical distraction and can be irritating.

[0010] US 4,462,399 teaches a PAPR system having filtering capability attached to a hard hat or helmet, but this attempt adds weight to the user's head, making the helmet top-heavy. Some PAPR systems can be carried as a backpack, encased in an elastic bag with shoulder straps to carry the device. However, this does not allow for the WLFF standard backpack to be worn or provide non-encumbering carrying methods. As a result, most existing PAPR systems would not encourage users to use these systems except when it is absolutely necessary, that is, in heavy toxic or hazardous smoke areas. However, Passive exposure to lower smoke levels during an entire work shift can also be hazardous to the WLFFs' health and reduce their effectiveness on the job.

[0011] The prior art suffers from at least one of the following limitations: it is too heavy, too large, encumbers the activity of a WLFF, does not perform for a long enough time, for example, at least 4 hours on a portable power source such as a battery, it requires too much power (Wh of electrical power) to operate for 4 hours, or it does not filter out the smoke, taste, and smell of toxins that a WLFF is exposed to during the course of their duties. Thus, improvements are needed.SUMMARY OF TH E INVENTION

[0012] The present disclosure teaches a breathing apparatus with a mask adapted to substantially surround at least the mouth or nostrils of a user. The breathing apparatus has a "non-encumbering" filtration component attached to the mask and adapted to attach to a non-encumbering location on the user. It is non-encumbering because it attaches to a wildland firefighter user in a manner that substantially does not impede the user's back of the neck, lower lumbar, or chest area. It has a flow generatorto receive unfiltered air from the surrounding environment, filter the unfiltered air using battery power or the user's breathing power, control the air pressure that is provided to the mask, adjust electrical power usage of the flow generator based on measured pressure to the mask (to extend battery life) and provide filtered air to the mask and the user. The non-encumbering filtration component is engaged with the mask by an air channel arranged to convey air from the flow generator to the mask.

[0013] The non-encumbering location on the user may be inside or attached to the backpack that the firefighter uses to carry a variety of their other equipment, but not directly attached to the user's back. It may be on a pre-existing strap-on point that does not impede a WLFF's arm swing and is within reach for using the respirator device without removing their backpack or other gear. The filtration component fits easily on any belt or strap, in backpack pockets, or preferably in a ventilated pouch, so it does not encumber the WLFF any more than the equipment they are already required to wear. The pouch, pocket, or other attachable accessory must allow up to 115 L / min of breathing air to reach the filtration component with minimal resistance. Preferably, a portion of the pouch or pocket located near the filtration unit's inlet is a mesh or highly air-permeable fabric to allow air flow, preferably the bottom surface to minimize dirt, rain, or other debris of material from entering the filter.

[0014] The non-encumbering filtration component produces at least 115 L / min airflow to the mask while being no more than 3500 cubic centimeters in volume. It delivers 115 L / min of filtered air for at least four (4) continuous hours with at most 140 Wh of a battery supply. The internal rechargeable battery may be a lithium or lithium-ion battery, and may be recharged during periods of use or non-use. A battery-saving algorithm adjusts the blower power so the wildland respirator (WR) can operate efficiently for at least a 4 hours without recharge.

[0015] The WR algorithm uses pressure readings from a differential pressure sensor to adjust the blower output. The differential pressure sensor compares atmospheric pressure to the pressure in the breathing hose, and the Differential Pressure Sensor Reading, the Current Breathing Level, and the current Blower Power are used as inputs to the battery-saving algorithm. Based on the inputs, the algorithm will change the Breathing Level (Light, Medium, Heavy) and Blower Power (base duties).

[0016] The disclosure provides a breathing apparatus comprising: a mask, wherein the mask is adapted to surround at least the mouth or the nostrils of a user; a non-encumbering filtration component, further comprising a flow generator; and, an air channel attaching the non-encumbering filtration component to the mask, which conveys air from the flow generator to the mask. The non-encumbering filtration component is adapted to attach to a backpack. Preferably, the non-encumbering filtration component attaches to non-encumbering location on the user and does not impede the user's back of neck, lower lumbar, or chest area. The non-encumbering filtration component may fit in or on the pockets, waistband, straps, or other non-encumbering locations of the backpack or other gear that WLFFs are already required to wear during their shifts, so long as 115 L / min airflow can enter the filtration component with minimal resistance. Preferably, it is located in a storage pouch with a ventilated bottom.

[0017] The flow generator receives and filters unfiltered air from a surrounding environment with a battery power supply, controls the air pressure provided to the mask, and adjusts power usage based on a measured pressure to the mask.

[0018] The non-encumbering filtration component may fit in or attached to the pockets, waistband, straps, or other non-encumbering locations of the backpack or other gearthat WLFFs are already required to wear during their shifts. Preferably, it attaches to the outer side of the WLFF backpack or gear, and a WLFF can comfortably access the power button without removing their backpack or gear.

[0019] In an embodiment, the non-encumbering filtration component has a volume of at most 3500 cubic centimeters, wherein the non-encumbering filtration component produces an airflow to the mask of at least 115 L / min. It may continually produce an airflow to the mask of 115 L / min for at least 4 hours with a battery power supply of at most 140 Wh. With the battery-saving algorithm, the non-encumbering filtration component can be operable for at least 4 hours. The internal rechargeable battery may be a lithium battery or a lithium-ion battery.

[0020] The non-encumbering filtration component may further comprise a charging port. Preferably, it is a USB charging port with between 7.5 and 60 Watts power delivery. A user may attach a personal battery charger and charging cable to the charging port and extend the lifetime of the WR.

[0021] In an embodiment, the non-encumbering filtration component of the disclosed breathing apparatus further comprises: a blower and a filter cartridge attached to the blower, further comprising a particulate filter and an activated carbon filter. The blower draws the unfiltered air from the surrounding environment through the filter cartridge and to the mask at an air flowrate, with the following rates of removal of one or more toxins from the unfiltered air: when the air flowrate is 115 L / min, the filter cartridge reduces acrolein in the unfiltered air from 10 ppm to below 0.1 ppm for at least 20 minutes; when the air flowrate is 115 L / min, the filter cartridge reduces cyclohexane in the unfiltered air from 300 ppm to below 10 ppm for at least 20 minutes; when the air flowrate is 115 L / min, the filter cartridge reduces formaldehyde in the unfiltered air from 50 ppm to below 1 ppm for at least 30 minutes; when the air flowrate is 115 L / min, the filter cartridge reduces NO2in the unfiltered air from 25 ppm to below 1 ppm for at least 30 minutes; and when the air flowrate is 115 L / min the filter cartridge reduces SO2in the unfiltered air from 50 ppm to below 5 ppm for at least 30 minutes.

[0022] In an embodiment, the breathing apparatus further comprises a printed circuit board, wherein the printed circuit board executes an algorithm to adjust the battery power delivered to the blower for efficient use of battery power, and wherein the battery power lasts for at least 4 hours. Preferably, the algorithm uses a differential pressure sensor reading, a current breathing level, and a current blowerpower to select a new breathing level and a new blower power. The breathing apparatus may further comprise an internal rechargeable battery pack and a particulate and gas filter.

[0023] The disclosure also provides a method of operating a breathing apparatus, the steps comprising: a) providing a breathing apparatus, the breathing apparatus comprising: a mask, wherein the mask is adapted to surround at least the mouth or the nostrils of a user; a non-encumbering filtration component, further comprising: a flow generator, a rechargeable battery pack, a circuit board assembly, a blower, a particulate and gas filter attached to the blower, and a differential pressure sensor assembly; and, an air channel attachingthe non-encumbering filtration component to the mask; wherein, the non-encumbering filtration component is adapted to attach to a non-encumbering location on the user; wherein, the nonencumbering filtration component does not impede the user's back of neck, lower lumbar, or chest area; wherein, the flow generator receives and filters an unfiltered air from a surrounding environment with a battery power supply, controls an air pressure provided to the mask, and adjusts a power usage based on a measured pressure to the mask; wherein, the air channel conveys air from the flow generator to the mask; and, wherein, the non-encumbering filtration component has a volume of at most 3500 cubic centimeters, and wherein the non-encumbering filtration component produces an airflow to the mask of at least 115 L / min; b) continually filtering the unfiltered air from the surrounding environment, producing an airflow to the mask of at least 115 L / min, for at least 4 hours with a battery power supply of at most 140 Wh; c) automatedly measuring a pressure drop with the differential pressure sensor assembly; d) executing an algorithm by the circuit board assembly, wherein the algorithm adjusts a breathing level and a duty cycle based on an air pressure from the pressure drop, the algorithm further comprising the steps of: i) operating the blower at a base duty cycle; ii) raising the duty cycle of the blower if the air pressure provided to the mask drops below a pressure setpoint; iii) raising the breathing level to a next highest breathing level if the air pressure provided to the mask does not rise to the pressure setpoint; iv) returning the blower to the base duty cycle if the air pressure provided to the mask returns to the pressure setpoint; v) lowering the breathing level to a next lowest breathing level if the air pressure provided to the mask remains above the pressure setpoint.

[0024] In one embodiment of the method, the pressure setpoint for Light Breathing is 300 Pascals, and the base duty for Light Breathing is 50% (5.5 Watts); wherein the pressure setpoint for Medium Breathing is 375 Pascals and the base duty for Medium Breathing is 55% (6.66 Watts); and, wherein the pressure setpoint for Heavy Breathing is 450 Pascals, and the base duty for Heavy Breathing is 60% (8.0 Watts).

[0025] In another embodiment, the pressure setpoint for Light Breathing is 375 Pascals, and the base duty for Light Breathing is 55% (6.66 Watts); wherein the pressure setpoint for Medium Breathing is 450Pascals, and the base duty for Medium Breathing is 60%, (8.0 Watts); and, wherein the pressure setpoint for Heavy Breathing is 525 Pascals and the base duty for Heavy Breathing is 65% (9.4 Watts).

[0026] In another embodiment, the pressure setpoint for Light Breathing is 375-450 Pascals, and the base duty for Light Breathing is 55-60% (6.66-8.0 Watts); wherein the pressure setpoint for Medium Breathing is 450-525 Pascals and the base duty for Medium Breathing is 60-65% (8.0-9.4 Watts); and, wherein the pressure setpoint for Heavy Breathing is 525-600 Pascals and the base duty for Heavy Breathing is 65-70% (9.4-11.1 Watts).BRI EF DESCRIPTION OF FIGURES

[0027] Figure 1: Filtration unit of the breathing apparatus.

[0028] Figure 2: Filtration unit of the breathing apparatus A) first inner view B) second inner view.

[0029] Figure 3: Wildland firefighter wearing filtration unit, connecting hose, and mask.

[0030] Figure 4: Wildland firefighter wearing filtration unit located in storage pouch.

[0031] Figure 5 : Power management control algorithm.

[0032] Figure 6: User interface button function algorithm.DETAI LED DESCRI PTION OF TH E INVENTION

[0033] Wildland firefighters need a respirator to protect them against particulate and chemical vapor hazards during Wildland and Wildland Urban Interface (WUI) firefighting operations. A respiratory protective device (RPD) for WLFFs must be light, small, easy to don and doff, comfortable to wear, and durable. Wildland RPDs must require minimal maintenance, be affordable for smaller fire departments with limited budgets, and have low operating costs (i.e., not require frequent replacement of expensive filter cartridges).

[0034] The wildland respirator of the present disclosure is differentiated from PAPRs in the prior art due to its combination of performance metrics (ability to deliver 115 Lpm for at least 4 continuous hours, filter specific toxins of concern to the wildland firefighter, a small cube / weight, and it doesn't get in the way of the wildland fire fighter's comfort or job functions - i.e., it is non-encumbering). The present disclosure teaches a "non-encumbering" filtration component that doesn't get in the way of existing wildland firefighting equipment, and that it is not located on the wearer's head or neck area, the front chest where a radio is mounted, orthe lower lumbar. In optional specific embodiments it is: (1) not on the user's chest,on the user's neck, or directly contacting the user's back; (2) not too heavy or voluminous; (3) does not contribute excessively to heat load or other physical strain; (4) is preferred over other respiratory protective devices because it is less annoying to carry or use while wearing a wildland firefighting webpack; and, (5) doesn't get in the way of other existing wildland firefighting equipment.

[0035] The present disclosure solves the limitations of the prior art by providing a wildland firefighter PAPR that is both non-encumbering and able to perform at a sufficient filtration level for a sufficient duration while also having a low mass and volume such that it meets the critical needs of the WLFF. The PAPR has a non-encumbering filtration component of no more than 2 kg, which consists of a half mask, breathing hose, blower module, Carbon & HEPA Filter, and an internal rechargeable battery pack (140 Wh). Alternative battery configurations are possible, but the internal rechargeable lithium-ion cell is at most 140 Wh. The system uses an algorithm to precisely control the power output to the blower that effectively balances recharging the internal battery cell (for higher pulse power requirements) and conserving energy during more extended periods without high power output.

[0036] Ideally, the Wildland PAPR is carried in an accessory pocket on the side of the backpack to keep it out of the WLFF's arm swing zones when walking or using hand tools but leaving it low enough that the WLFF can reach the power button to turn it on without removing their backpack. Accessory pockets to hold the Wildland PAPR should allow up to 115 Liters / minute of breathing air to reach it with minimal resistance. Ideally, an accessory pocket for the Wildland PAPR would protect it from airborne embers and rain while permitting air to get to the unit without restriction. The Wildland PAPR system's accessory pocket will hold the system in its assembled state: filter connected to the blower / battery housing and air hose attached. Preferably, the top of the pouch is water and fire-resistant, and the bottom is a fire- resistant mesh to allow unrestricted airflow while protecting the respirator from debris.

[0037] The Wildland PAPR fits easily on any belt or strap or in backpack pockets with adequate ventilation. Its cylindrical shape means it does not contact much of the WLFF's torso when worn on a belt or strap, so it doesn't add to heat load by covering torso areas used in evaporative cooling.

[0038] The air hose is equipped with swiveling fittings in orthogonal planes: one perpendicular to the axis of the breathing hose and one parallel to the axis of the breathing hose. The dual swivel fittings reduce the perceived pull of the breathing hose and half-mask on the WLFF's head, nose, face, and neck. Ideally, the air hose is rigged to follow the backpack's shoulder strap to the point that it turns and heads to the WLFF's nose and mouth (airway). By tracing the backpack's shoulder strap, the air hose doesn't occupy torso space.

[0039] The Wildland Respirator Control Algorithm is shown in Figure 5. The algorithm takes the Differential Pressure Sensor reading, current Breathing Level, and current Blower Power as inputs (Label A). Based on the Differential Pressure Sensor reading, the algorithm changes the Breathing Level and Blower Power. The first time the algorithm runs, it starts at the Light Breathing Level and will not change the Breathing Level until the pressure in the hose surpasses the minimum pressure of the Light Breathing Level (Label B). After the minimum pressure has been met initially, the algorithm can change the Breathing Level (Label C). If the hose pressure does not rise to the setpoint within 30 milliseconds, the algorithm will raise the Breathing Level to account for heavier breathing. Similarly, if the hose pressure stays above the setpoint for 1 second, the algorithm will lower the Breathing Level to account for lighter breathing. Each Breathing Level described in this disclosure (Light Breathing, Medium Breathing, Heavy Breathing) as a different pressure setpoint and base duty cycle (Label D). The Algorithm compares the Differential Pressure reading to the pressure setpoint associated with the current Breathing Level (Label E). If the Differential Pressure reading is below the pressure setpoint, a PID is used to raise the current Blower Power (Label F). If the Differential Pressure reading is above the pressure setpoint of the current Breathing Level, then the current Blower Power is set to the base power associated with the current Breathing Level (Label G). The program then exits the algorithm until the next call in 10 milliseconds (Label H).

[0040] The pressure setpoints and base duty cycles may be pre-set, wherein the base duty cycle maintains the mask pressure just above the pressure setpoint. Inhale detection corresponds to the mask pressure going below the pressure setpoint (breathing in will lower the pressure in the mask).

[0041] Pressure setpoints and base duty for each Breathing Level are optionally as follows: the pressure setpoint for the Light Breathing Level is 300 pascals, and the base duty is 50%. The pressure setpoint for the Medium Breathing Level is 375 pascals, and the base duty is 55%. The pressure setpoint for the Heavy Breathing Level is 450 pascals, and the base duty is 60%, alternative setpoints are described elsewhere in this disclosure.

[0042] In the Specification and the accompanying Claims, the following terms are given their plain meaning as well as the additional meanings written below.

[0043] The term "internal rechargeable battery" means a non-user-serviceable secondary battery pack positioned inside the WR's housing. It can include a battery pack with a preferred maximum current draw of 4 Amps, with less preferred embodiments incorporating a battery pack of up to 8 Amps maximum current draw.

[0044] The term "blower" means an integrated assembly of an electric motor, an air impeller, and a housing that creates an air-moving device capable of pulling air through the WR's filters and pushingfiltered air to the user and can include non-limiting examples such as radial or axial fans with the power to move at least 115 Lpm of air against a pressure of at least 900 Pa.

[0045] The term "breathing apparatus" means a device that facilitates breathing in conditions that could cause respiratory system injuries if protective measures, such as filtering contaminated breathing air, are not taken.

[0046] The term "mask" is an airway-covering device capable of passing a Fit Test. The WR half mask has at least one air inlet with a one-way valve, at least one exhaust valve with a one-way valve, and a retention system that keeps the mask in place over the user's airway during Wildland Firefighting operations.

[0047] The term "Fit Test" can be found in the 42 CFR 84 referenced document containing NIOSH fit testing regulations.

[0048] The term "WLFF backpack" refers to a backpack designed to be stable, durable, and ergonomic for carrying heavy loads and supplies to fire sites. They often comprise padding, harnesses, and extra straps for a comfortable wear and easy attachment of extra items. The WLFF backpack does not support burning, and is a part of their required gear.

[0049] The term "non-encumbering filtration component" means a filtration componentthat doesn't get in the way of existing wildland firefighting equipment, including the head and neck area, the front chest (where a radio is mounted), the lower lumbar or on the back (and not inside a backpack). In optional specific embodiments, it is (1) not on the user's chest, not on the user's neck, or not directly contacting the user's back, (2) not too heavy or voluminous, (3) does not contribute excessively to heat load or other physical strain, (4) preferred over other respiratory protective devices because it is less annoying to carry or use while wearing a wildland firefighting webpack and (5) doesn't get in the way of other existing wildland firefighting equipment or job functions.

[0050] The term "non-encumbering location" on the user can include areas on the hip belt of the WLFF backpack, in or on the WLFF backpack, or remotely or unmounted when operating vehicles or earthmoving equipment. If attached to a backpack on the user, the WR can be mounted inside a ventilated pocket or on the outside of the WLFF backpack. The storage pocket, alternatively referred to as a storage pouch, or a ventilated pocket, may be attached to the backpack, but not contain inside the backpack. The ventilated pocket may be an auxiliary pocked affixed to the external surface of the backpack. The system should be located on the user substantially in a manner that does not impede the user's back of neck, lower lumbar, middle or upper back where the WLFF backpack must contact the user's torso or chest area. Preferably, the non-encumbering location is attachable to a universal attachment strap such as Modular Lightweight Load-carrying Equipment (MOLLE) strap, out of the way of a WLFF's arm swing zones whilewalking or using hand tools. A WLFF must be able to reach the power button and turn it on and off without removing their backpack.

[0051] The term "flow generator" means blower, as defined above.

[0052] The term "unfiltered air" means wildland fire smoke or breathing air containing particulates or chemical contaminates generated by incomplete combustion of burning biomass.

[0053] Filtering the unfiltered air means removing at least 99.97% of all sizes of particulates, including particulates with a size of 0.3 microns, and removing chemical components of unfiltered air listed in EPA governing regulations.

[0054] The term "filtered air" means air that has been drawn through the filtration elements. Filtered air has had at least 99.97% of particulates 0.3 microns removed, which is classified as the most penetrating particle size (MPPS), and chemical components of unfiltered air listed in governing regulations removed.

[0055] The term "air channel" means the path that contaminated wildland fire air takes after it has been drawn through the filters and pulled into the blower, when it is pushed into the breathing hose, and finally into the mask, giving the user access to filtered, positively pressured air.

[0056] The term "internal battery" means a non-removable secondary battery pack, preferably a 3S-xP (i.e., 3S1P, 3S2P, 3S3P, etc.) battery pack, of lithium-ion or lithium polymer chemistry, with working voltages from 12.6 V down to 9.0 V.

[0057] The term "filter cartridge" for the WR can mean a single filter combining all or some of the following elements: spark arrestor, prefilter, HEPA filter, carbon bed, and CO-Oxidation catalyst. The WR can be outfitted with appropriate filter cartridges to address hazards WLFFs encounter in various geographical regions or incidents. The "filter cartridge" can also mean / refer to stackable filtration components that lock together to form the WR's multi-component filter.

[0058] The term "toxins" refers to hazardous chemical components of wildland fire smoke listed in NFPA 1984 Table 8.11.4.

[0059] The term "storage pouch with a ventilated bottom" (alternatively storage pocket, or ventilated pocket) all mean a pocket, pouch, or other accessory that is attachable to the external surface of a backpack, such as a WLFF backpack. Preferably, it is attachable to a universal attachment strap such as MOLLE straps. The ventilated bottom, or ventilation, allows external air to pass into the storage pouch and enter the WR at up to 115 L / min with minimal resistance. The ventilation is preferably a mesh bottom of the pouch or pocket. Mesh may be a porous fabric, nylon mesh and the like. The storage pouch must fit the respiratory system in its assembled state, operably such that the air passing through the ventilatedportion, or bottom mesh, can enter the inlet of the filtration component: for example, the filter connected to the blower / battery housing and air hose attached.

[0060] The term "battery cover" means a housing that protects the optional auxiliary battery pack from the elements.

[0061] The term "battery frame" means a part of the housing into which the battery cover attaches.

[0062] The term "internal rechargeable battery pack cover" means a part of the housing that protects the internal battery pack.

[0063] The term "upper housing" means a part of the housing that interfaces between the unit and the breathing tube.

[0064] The term "first clamshell housing" means a part of the housing that contains the blower and the PCB assembly.

[0065] A power inlet is used to supply DC power to charge the internal battery. The DC power source can be a DC power supply 5 V to 20 V, preferably implementing the USB-PD specification to negotiate supplied power.

[0066] The term "charging port" means a DC power inlet used to charge the internal battery. Preferably, the charging port will be a USB-C port capable of delivering up to 7.5 Watts of power. The USB-C charging port may be accompanied by circuitry implementing the USB PD (Power Delivery) specification to deliver up to 60 Watts of power.

[0067] The "control button" is a momentary pushbutton containing an RGB (red, green, and blue) LED that can display information to the user. Other color indicators are possible.

[0068] The circuit board assembly contains electronics to perform the required functions of the respirator. It controls the charging of the internal battery pack from the power inlet. The circuit board assembly also uses the absolute pressure sensor, differential pressure sensor, and blower in accordance with the Wildland Respirator Control Algorithm (Figure 5).

[0069] The "bypass valve" allows the user to manually breathe through the unit even when the unit is unpowered.

[0070] The "second clamshell housing" is part of the housing that contains the blower and the PCB assembly.

[0071] The "lock ring" is part of the housing, having features to join the housing to the filter port.

[0072] The "filter port" is part of the housing that interfaces with the filter and directs the filtered air into the housing with the blower.

[0073] The "gas filter" means the carbon filtration component, carbon bed, or activated carbon used to remove hazardous chemical components of wildland fire smoke listed in NFPA 1984 Table 8.11.4.

[0074] "Automatedly measuring the pressure drop" means using the differential pressure sensor assembly to measure the pressure drop across the blower and provide a Differential Pressure Sensor reading. This is performed so that the device can execute an algorithm by the circuit board assembly.

[0075] "Executing an algorithm by the circuit board assembly" means executing an algorithm as shown in Figure 5, which takes the Differential Pressure Sensor reading, the current Breathing Level, and the current Blower Power as inputs (Label A). The algorithm keeps the motor running at the base duty until the hose pressure goes below the current pressure setpoint due to a user inhalation. At this point, the PID (Proportional-lntegral-Derivative) control raises the blower's duty cycle to keep the pressure inside the hose above the ambient pressure outside the hose (Label E). Once the hose pressure returns to the pressure setpoint, the control algorithm returns the motor to the base duty cycle. If the hose pressure does not rise to the setpoint within 30 milliseconds, the algorithm will raise the Breathing Level to account for heavier breathing. Similarly, if the hose pressure stays above the setpoint for 1 second, the algorithm will lower the Breathing Level to account for lighter breathing (Label C). A flag is used to register when the pressure setpoint is reached for the first time to keep the Breathing Level from changing when the algorithm is first started. After setting this flag, the algorithm can change the Breathing Level (Label B).

[0076] The pressure setpoints and base duty for each Breathing Level are optionally as follows: the pressure setpoint for the Light Breathing Level is 300 pascals, and the base duty is 50%. The pressure setpoint for the Medium Breathing Level is 375 pascals, and the base duty is 55%. The pressure setpoint for the Heavy Breathing Level is 450 pascals, and the base duty is 60%.

[0077] An optional set of pressure setpoints and base duty cycles (with corresponding power consumptions) is 375 Pascals pressure setpoint and 55% base duty (6.66 Watts) for Light Breathing; 450 Pascals pressure setpoint and 60% base duty (8.0 Watts) for Medium Breathing; 525 Pascals pressure setpoint and 65% base duty (9.4 Watts) for Heavy Breathing. Other less preferred ranges of pressure setpoints and base duty cycles are 375 to 450 Pascals pressure setpoint and 55% to 60% base duty (6.66 Watts to 8.0 Watts) for Light Breathing; 450 to 525 Pascals pressure setpoint and 60% to 65% base duty (8.0 Watts to 9.4 Watts) for Medium Breathing; 525 to 600 Pascals pressure setpoint and 65% to 70% base duty (9.4 Watts to 11.1 Watts) for Heavy Breathing.

[0078] PID (Proportional-lntegral-Derivative) describes a control scheme that uses a reference (the Differential Pressure Sensor reading) and a setpoint (based on the Breathing Level) as inputs. Its output isdetermined based on the difference between the reference and the setpoint and is used to modify the blower power.

[0079] The absolute pressure sensor measures the pressure inside the WR's housing, downstream from the filters and before the blower. When the WR's blower runs, the absolute pressure sensor monitors subambient pressures to determine the pressure drop across the filter. The WR's safety algorithm monitors absolute pressure sensor readings to confirm that the pressure drop across the filter is acceptable. If the pressure drop across the filter becomes too large, greater than 870 Pa, the WR will flash a warning signal for the user to replace the filter.

[0080] The differential pressure sensor compares atmospheric pressure to the pressure in the breathing hose. The WR's blower control algorithm uses pressure readings from the differential pressure sensor to adjust the blower output. The purpose of the differential pressure sensor is to give the WR a way to adjust blower output to maintain a positive pressure of at most 450 Pa, sometimes 375 Pa, and at least 300 Pa in the breathing hose when the WR is in use. In optional embodiments, the maximum positive pressure may be higher, or 525 Pa, or less preferably 600 Pa. When a user inhales, the pressure lowers in the mask, and heavier inhalation may trigger the blower control algorithm to increase the blower output.

[0081] The hose is a conduit to conduct air from the blower to the mask. The hose should create a pressure drop of less than 30 mm H2O at 115 Lpm airflow, while 20 mm H2O at 115 Lpm is preferred, and 10 mm H2O at 115 Lpm pressure is even more preferred. The hose or hose with a protective sheath must not burn without significant energy input. Burning may occur in contact with the hot wire, however it must not continue to burn if the hot wire is no longer in contact with the hose.

[0082] The mask is an airway covering device capable of passing a fit test. The WR half mask has at least one air inlet with a one-way valve, at least one exhaust valve with a one-way valve, and a retention system that keeps the mask in place over the user's airway during Wildland Firefighting operations.

[0083] The PAPR of the present disclosure is capable of treating air with acrolein. When exposed to a high concentration of 10 ppm Acrolein in 25 °C air flowing at 115 Lpm, it reduces the acrolein in the breathing air to below 0.1 ppm. This condition is met at 80 % relative humidity and 25 % relative humidity. The PAPR can treat this high acrolein exposure for at least 20 minutes, with effluent concentrations staying below 0.1 ppm for at least 20 minutes. The device can run for 4 hours, providing purified air or treating a shorter duration with a higher concentration of acrolein.

[0084] The PAPR of the present disclosure is capable of treating air with cyclohexane. When exposed to a high concentration of 300 ppm Cyclohexane in 25 °C air flowing at 115 Lpm, it reduces the Cyclohexane in the breathing air to below 10 ppm. This condition is met at 80 % relative humidity and also at 25 %relative humidity. The PAPR can treat this high Cyclohexane exposure for at least 20 minutes, with effluent concentrations staying below 10 ppm for at least 20 minutes. The device overall can run for 4 hours, providing purified air while also being able to treat a shorter duration high spike of cyclohexane concentration during the work shift.

[0085] The PAPR of the present disclosure is capable of treating air with formaldehyde. When exposed to a high concentration of 50 ppm formaldehyde in 25 °C air flowing at 115 Lpm, it reduces the formaldehyde in the breathing air to below 1 ppm. This condition is met at 80 % relative humidity and also at 25 % relative humidity. The PAPR can treat this high formaldehyde exposure for at least 30 minutes, with effluent concentrations staying below 1 ppm for at least 30 minutes. The device overall can run for 4 hours, providing purified air while also being able to treat a shorter duration high spike of formaldehyde concentration during the work shift.

[0086] The PAPR of the present disclosure is capable of treating air with nitrogen dioxide. When exposed to a high concentration of 25 ppm nitrogen dioxide in 25 °C air flowing at 115 Lpm, it reduces the nitrogen dioxide in the breathing air to below 10 ppm. This condition is met at 80 % relative humidity and also at 25 % relative humidity. The PAPR can treat this high nitrogen dioxide exposure for at least 20 minutes, with effluent concentrations staying below 25 ppm for at least 30 minutes. The device overall can run for 4 hours, providing purified air while also being able to treat a shorter duration high spike of NO2concentration during the work shift.

[0087] The PAPR of the present disclosure is capable of treating air with Sulfur Dioxide. When exposed to a high concentration of 50 ppm sulfur dioxide in 25 °C air flowing at 115 Lpm, it reduces the sulfur dioxide in the breathing air to below 5 ppm. This condition is met at 80% relative humidity and also at 25% relative humidity. The PAPR can treat this high sulfur dioxide exposure for at least 30 minutes with effluent concentrations staying below 5 ppm for at least 30 minutes. The device overall can run for 4 hours, providing purified air while also being able to treat a shorter duration high spike of SO2concentration during the work shift.

[0088] The PAPR of the present disclosure is capable of 150 L / min airflow to mask with a nonencumbering filtration component of at most 4500 cc (cubic centimeters), preferably at most 3700 cc, more preferably at most 3500 cc, which includes all components including the canister, the nonencumbering filtration component, the mask and the tube connecting the mask to the filtration component. In an embodiment, the non-encumbering filtration component combined with the filter cartridge is at most 2000 cc, preferably at most 1850 cc, and more preferably at most 1700 cc. In another embodiment, the non-encumbering filtration component without the filtration canister is at most 1500cc, preferably 1250 cc, more preferably at most 1150 cc. It is further able to pass all short-duration, high- concentration filtration metrics above (acrolein, cyclohexane, formaldehyde, NO2, SO2) while effectively operating at 115 L / min for least 4 continuous hours with at most 140 Wh, preferably at most 130 Wh, optionally at most 144.45 Wh of battery supply. The battery may be recharged during periods of use or during periods of non-use through wire connection to the charging port, preferably a USB-C port.

[0089] The PAPR of the present disclosure may also contain a printed circuit board executing an algorithm to adjust the power delivered to the blower / fan to use battery power efficiently and enable the small device's operation for the 4-hour minimum operation period.

[0090] Figure 1 shows the Wildland Respirator (WR), a lightweight, ruggedized PAPR with a HEPA filter and an NFPA 1984 Class 2 carbon filter. Class 2 carbon filters protect WLFFs from chemical vapors in wildfire smoke, and CO protection is possible with an optional filter. In the version of the wildland firefighter PAPR shown in Figure 1, the filtration component includes a battery cover (3), a rechargeable battery pack door (119), an internal rechargeable battery (117), upper housing (2), first clamshell housing (1), a control button (9), a circuit board assembly (18), a bypass valve (13), an indicator (118), a blower (6), a blower cover (5), second clamshell housing (12), a lock ring (11), and a filter port (7). The filtration component can be attached to a particulate and gas filter (4). The filtration component may comprise an optional belt clip (10) and screws (14).

[0091] The particulate filter comprises a filtration element designed to remove particles present in air. The particulate filter must remove at least 99.97% of airborne particles, including the most penetrating particle size (0.3 microns). The filter works better for particles above and below 0.3 microns.

[0092] The carbon filtration component, also referred to as the gas filter, is a bed of activated carbon that has the capacity to remove hazardous gases from wildland fire smoke.

[0093] Figure 2 shows internal views of the WR filtration unit. Figure 2A shows the inner view below the second clamshell housing (12) with a charging port (15), a circuit board assembly (18), a bypass valve (13), an indicator (118), a blower (6), and an optional belt clip (10). Figure 2B shows the inner view below the first clamshell housing with a battery cover (3), a rechargeable battery pack door (119), and an internal rechargeable battery (117). Both views also show a filter port (7) connected to a particulate and gas filter (4).

[0094] The WR filtration unit connects with external components that form the entire wildland firefighter PAPR device. Attached to the mask are system components that include the breathing hose, a mask retention system, and possibly a passive or active voice amplification or transceiver system. Filtered air travels from the PAPR through a breathing air hose to a half mask. The WR's half-mask has an exhalationvalve capable of expelling liquids and gases. The WR's half-mask comes in three sizes to fit 99% of the adult population. The mask comprises adjustable head straps that may fit comfortably around two locations on the back of a user's head. The hose may comprise a protective sleeve which does not support burning.

[0095] Figure 3 shows the entire wildland firefighter PAPR device with all components in use on a firefighter. The WR filtration device (100) with an attached particulate and gas filter (4) is operable with a control button (9). Filtered air travels through a breathing hose (201) to a mask (202) which is fitted to a user's face with adjustable straps (203). The PAPR device may be connected externally to a WLFF backpack (200).

[0096] Preferably, the WR is located in a storage pouch or pocket with a ventilated bottom, as shown in Figure 4. The storage pouch (300) with a ventilated bottom (302) and an optional zipper (305) is located externally on the WLFF backpack (200) and is within reach of a user. The storage pouch (drawn in Figure 4 as see-through so the internal contents are visible) fits the WR filtration device (100) with an attached particulate and gas filter (4), and does not impede a user's access to a control button (9). Filtered air travels through a breathing hose (201) to a mask (202) which is fitted to a user's face with adjustable straps (203).

[0097] The shape of the WR is roughly cylindrical, with a maximum diameter of 4 to 5 inches, with a maximum height of 8 to 10 inches. It can replace a water bottle on WLFFs1backpack hip belts. The WR's belt clips work with mounting straps, although the WR's belt clips are versatile and will work on most straps, pockets, and belts. The WR does not require extra clothing or cumbersome attachments to the WLFF beyond what they are already required to wear on the job. The WR may be located inside the backpack if there is sufficient ventilation of air through the backpack material, or it may attach loosely on the outside of the backpack.

[0098] Preferably, the WR is located in a storage pouch with ventilation that is attachable to the outside of a WLFF backpack, maybe to universal attachment straps such as MOLLE straps. The storage pouch may be a storage pocket, where the ventilation is an opening in the pocket to the environment. The storage pouch may be partially or entirely comprised of a mesh or air-permeable material for ventilation. Preferably, the top majority of the storage pouch is made from a water-resistant, non-burning, protective material, and the bottom of the storage pouch is made from a mesh, porous, or air-permeable fabric that allows air to pass into the respirator device with minimal resistance. The storage pouch prevents dust, debris, rain etc. from damaging the filter or clogging the inlet. The storage pouch must allow for 115 L / minof airflow to reach the inlet of the filtration component with minimal resistance. The storage pouch or pocket with ventilation is preferably attachable to universal attachment straps, for example MOLLE straps.

[0099] The WR is a tight-fitting PAPR that will deliver at least 115 Lpm of filtered air for four hours, per 42 CFR 84 Subpart K, which is incorporated by reference herein. The WR is operable for 4 hours without recharge, where WLFFs may don and doff the respiration device based on varying environmental conditions accounting for up to 4 hours of spikes in specific toxins. Because the WR may not be in operation at all times, it may be used for at least an 8 hour shift, with an actual run-time of up to 4 hours.

[0100] The WR may be recharged through a charging port, preferably a USB-C port with PD. The WR may be recharged during periods of use or non-use. With a non-PD, USB-C charging port the internal battery may be recharged during periods of non-use, orthe runtime may be extended by providing supplemental power to the internal battery during use. With a USB-C PD charging port providing between 27 and 60 Watts, the internal battery may be recharged during periods of use or non-use. In periods of use the internal battery will be recharged and the WR will have power supplied by the USB-C PD charging port, allowing the WR to be powered completely from an external power source.

[0101] Benefits of the Disclosure include: (1) The WR tolerates high-temperature environments (at least 177 °C when not in operation and up to 50 °C when in operation). (2) Lowers breathing resistance due to positive pressure (of at most 450 Pa, sometimes 375 Pa, and at least 300 Pa in the breathing hose) air delivery. (3) It is not disruptive to a wildland firefighter's range of motion; (4) Minimizes possible snag hazards by routing system elements next to existing WLFF equipment; (5) Allows firefighters to communicate effectively while wearing its mask; (6) Easy to don and doff; (7) Provides a mask that fits snuggly over the mouth and nose; (8) Provides comfortable mounting options, including swiveling breathing hose fittings and an extensible breathing hose that reduces forces applied by the breathing hose to the mask when users move their heads; and. (9) It is easy to deploy when stowed.

[0102] The Wildland Respirator Control Algorithm uses Breathing Levels to adjust the PID control dynamically with the breathing effort of the user. There are 3 different breathing levels: Light, Medium, and Heavy. Each breathing level has a minimum differential pressure and a base blower power, as described above.

[0103] Wildland Respirator Modes: The Wildland Respirator device has four modes: Off, Standby, On, and Flow Test. Figure 6 shows the user-button interface for traversing between the four Modes.

[0104] Off Mode is the mode that the respirator will be in most of the time. It turns off the significant power-consuming peripherals and waits for user interaction. From the Off Mode, pressing the button any number of times will move the respirator into the Standby Mode.

[0105] In Standby Mode, the respirator will take a pressure reading of the atmospheric pressure, which can be used to compare to in the Flow Test Mode, in addition to powering on the peripherals that were turned off in Off Mode. After this, the respirator in Standby Mode will poll the differential pressure sensor to see if the pressure falls below the inhale detection threshold (-225 Pascals) and check for button presses. If the respirator does not detect an inhale for 10 seconds, then it will transition back to Off Mode. If the respirator does detect an Inhale while in Standby Mode, it will transition to On Mode. If the button is pressed once, the respirator will indicate the battery level of the secondary battery. If the button is pressed three times the respirator will transition to Flow Test Mode.

[0106] In On Mode the respirator will use the motor control algorithm to deliver the ideal amount of airflow to the user while breathing. The algorithm runs every 10 ms (100 Hz). In the On Mode the respirator detects inhalations by checking if the algorithm is required control the motor duty cycle higher than the base duty. If the motor stays at the base duty for 10 seconds, then the respirator assumes that no user is wearing the mask and transitions back to Standby Mode.

[0107] The last functional mode of the respirator is Flow Test Mode, which is entered by pressing the button three times while in Standby Mode. In the Flow Test Mode, the motor brings the hose pressure to a setpoint calibrated to correspond to 150 Lpm (Liters per Minute). The Flow test lasts 10 seconds, and if, in the end, the pressure inside of the housing is more than 870 pascals below the atmospheric pressure (measured in the Standby Mode), then the test has failed. If the pressure inside the housing is less than 870 pascals below the atmospheric pressure, then the test has passed. After completing the Flow Test, the respirator will always transition to Off Mode.

[0108] Pressure sensor operation: The electronics have two pressure sensors, an absolute sensor and a differential sensor. The absolute sensor takes a calibration at every startup and uses it to determine the occlusion of the filter. The differential pressure sensor has one port to the breathing tube, which is the same pressure as the breathing mask, and one port that goes to atmospheric pressure. This sensor controls the blower to assist breathing and determine the correct output flow during the flow test. Before operation, a flow test should be performed. This runs the unit to its maximum flow rate of 150 Lpm and ensures the filter does not provide too much breathing resistance. This is done using the differential pressure sensor to measure the pressure drop across a known orifice to read the flow while comparing the internal absolute pressure to the calibrated value to determine filter life.

[0109] Bypass Valve: In the event that the unit stops operation, the user can manually breathe through the filter. The bypass valve allows air to bypass the significant resistance of the blower and breathe cleanair from the filter. The unit will warn the user if the filter becomes too difficult to use in the case of unpowered operation at which point the user can change the filter to resume operation.

[0110] Although the present disclosure has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein, except where required by 35 U.S.C.§112 ,i 6 or 35 U.S.C.§112 (f).

[0111] All the features in this specification (including any accompanying claims, abstract, and drawings) may be replaced by alternative features serving the same, equivalent, or similar purpose unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed in one example only of a generic series of equivalent or similar features. Any element in a claim that does not explicitly state "means for" performing a specified function, or "step for" performing a specific function, is not to be interpreted as a "means" or "step" clause as specified in 35 U.S.C.§112 ,i 6 or 35 U.S.C.§112 (f). Any element in a claim that does explicitly state "means for" performing a specified function, or "step for" performing a specific function, is to be interpreted as a "means" or "step" clause as specified in 35 U.S.C.§112 ,i 6 or 35 U.S.C.§112 (f).

Claims

ClaimsWhat is claimed is...

1. A breathing apparatus, comprising: a) a mask, wherein the mask is adapted to surround at least the mouth or the nostrils of a user; b) a non-encumbering filtration component, further comprising a flow generator; and, c) an air channel attaching the non-encumbering filtration component to the mask; wherein, the non-encumbering filtration component is adapted to attach to a backpack; wherein, the flow generator receives and filters an unfiltered air from a surrounding environment with a battery power supply, controls an air pressure provided to the mask, and adjusts a power usage based on a measured pressure to the mask; and, wherein, the air channel conveys air from the flow generator to the mask.

2. The breathing apparatus of claim 1, wherein the non-encumbering filtration component is adapted to attached to a non-encumbering location on the backpack.

3. The breathing apparatus of claim 2, wherein the non-encumbering location on the backpack is inside a storage pouch with a ventilated bottom.

4. The breathing apparatus of claim 1, wherein the non-encumbering filtration component has a volume of at most 3500 cubic centimeters, and wherein the non-encumbering filtration component produces an airflow to the mask of at least 115 L / min.

5. The breathing apparatus of claim 4, wherein the non-encumbering filtration component continually produces an airflow to the mask of 115 L / min for at least 4 hours with a battery power supply of at most 140 Wh.

6. The breathing apparatus of claim 1, wherein the battery power supply is an internal rechargeable battery.

7. The breathing apparatus of claim 1, wherein the non-encumbering filtration component further comprises a charging port.

8. The breathing apparatus of claim 7 , wherein the charging port is a USB Power Deliver capable charging port.

9. The breathing apparatus of claim 1, wherein the non-encumbering filtration component further comprises: aa) a blower; and, bb) a filter cartridge attached to the blower, further comprising a particulate filter and an activated carbon filter; wherein, the blower draws the unfiltered air from the surrounding environment through the filter cartridge and to the mask at an air flowrate; wherein, the filter cartridge removes one or more toxins from the unfiltered air such that: when the air flowrate is 115 L / min, the filter cartridge reduces acrolein in the unfiltered air from 10 ppm to below 0.1 ppm for at least 20 minutes; when the air flowrate is 115 L / min, the filter cartridge reduces cyclohexane in the unfiltered air from 300 ppm to below 10 ppm for at least 20 minutes; when the air flowrate is 115 L / min, the filter cartridge reduces formaldehyde in the unfiltered air from 50 ppm to below 1 ppm for at least 30 minutes;when the air flowrate is 115 L / min, the filter cartridge reduces NO2in the unfiltered air from 25 ppm to below 1 ppm for at least 30 minutes; and, when the air flowrate is 115 L / min the filter cartridge reduces SO2in the unfiltered air from 50 ppm to below 5 ppm for at least 30 minutes.

10. The breathing apparatus of claim 9, further comprising a printed circuit board, wherein the printed circuit board executes an algorithm to adjust the battery power delivered to the blower for efficient use of battery power, and wherein the battery power lasts for at least 4 hours.

11. The breathing apparatus of claim 10, wherein the algorithm uses a differential pressure sensor reading, a current breathing level, and a current blower power to select a new breathing level and a new blower power.

12. A method of operating a breathing apparatus, the steps comprising: a) providing a breathing apparatus, the breathing apparatus comprising: i. a mask, wherein the mask is adapted to surround at least the mouth or the nostrils of a user; ii. a non-encumbering filtration component, further comprising: a flow generator, a rechargeable battery pack, a circuit board assembly, a blower, a particulate and gas filter attached to the blower, and a differential pressure sensor assembly; and, iii. an air channel attaching the non-encumbering filtration component to the mask; wherein, the non-encumbering filtration component is adapted to attach to a nonencumbering location on the user; wherein, the non-encumbering filtration component does not impede the user's back of neck, lower lumbar, or chest area;wherein, the flow generator receives and filters an unfiltered air from a surrounding environment with a battery power supply, controls an air pressure provided to the mask, and adjusts a power usage based on a measured pressure to the mask; wherein, the air channel conveys air from the flow generator to the mask; and, wherein, the non-encumbering filtration component has a volume of at most 3500 cubic centimeters, and wherein the non-encumbering filtration component produces an airflow to the mask of at least 115 L / min; b) continually filtering the unfiltered air from the surrounding environment, producing an airflow to the mask of 115 L / min, for at least 4 hours with a battery power supply of at most 140 Wh; c) automatedly measuring a pressure drop with the differential pressure sensor assembly; d) executing an algorithm by the circuit board assembly, wherein the algorithm adjusts a breathing level and a duty cycle based on an air pressure from the pressure drop, the algorithm further comprising the steps of: i. operating the blower at a base duty cycle; ii. raising the duty cycle of the blower if the air pressure provided to the mask drops below a pressure setpoint; iii. raising the breathing level to a next highest breathing level if the air pressure provided to the mask does not rise to the pressure setpoint; iv. returning the blower to the base duty cycle if the air pressure provided to the mask returns to the pressure setpoint; v. lowering the breathing level to a next lowest breathing level if the air pressure provided to the mask remains above the pressure setpoint.

13. The method of claim 12, wherein the pressure setpoint for Light Breathing is 300 Pascals and the base duty for Light Breathing is 50% (5.5 Watts); wherein the pressure setpoint for Medium Breathing is 375 Pascals and the base duty for Medium Breathing is 55% (6.66 Watts); and, wherein the pressure setpoint for Heavy Breathing is 450 Pascals and the base duty for Heavy Breathing is 60% (8.0 Watts).

14. The method of claim 12, wherein the pressure setpoint for Light Breathing is 375 Pascals and the base duty for Light Breathing is 55% (6.66 Watts); wherein the pressure setpoint for Medium Breathing is 450 Pascals and the base duty for Medium Breathing is 60% (8.0 Watts); and, wherein the pressure setpoint for Heavy Breathing is 525 Pascals and the base duty for Heavy Breathing is 65% (9.4 Watts).

15. The method of claim 12, wherein the pressure setpoint for Light Breathing is 375-450 Pascals and the base duty for Light Breathing is 55-60% (6.66-8.0 Watts); wherein the pressure setpoint for Medium Breathing is 450-525 Pascals and the base duty for Medium Breathing is 60-65% (8.0-9.4 Watts); and, wherein the pressure setpoint for Heavy Breathing is 525-600 Pascals and the base duty for Heavy Breathing is 65-70% (9.4-11.1 Watts).

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