Seal checking respirator filter adapter

Abstract

A respirator filter adapter, comprising: a main body having a rear-facing side configured to be connectable to an air inlet of a respirator, and a front-facing side configured to be connectable to an outlet of a filter, and an opening extending through the main body from the front-facing side to the rear- facing side; a lid arranged over the opening on the front-facing side of the main body, wherein the lid is movable between an open position in which the lid is spaced apart from the opening to permit air to flow through the opening, and a close position in which the lid covers the opening to prevent air from flowing through the opening; and a spring element arranged under the lid, wherein the spring element biases the lid towards the open position by default when no external force is applied on the lid, and the spring element is responsive to an external force selectively applied on the lid by permitting the lid to be temporarily actuated to the close position.

Description

SEAL CHECKING RESPIRATOR FILTER ADAPTERTECHNICAL FIELD

[0001] The present disclosure relates to accessories for respiratory' protection devices, in particular, respirator filter adapters.BACKGROUND

[0002] Respirator filter adapters are accessories used to connect filters to respirators. It may be used to connect filters to respirators which do not have a compatible connection with the connectors on the filters, allowing for versatility and customization based on individual specific needs. It may also serve to enable a respirator that comes with a standard filter to upgrade to a higher-efficiency or specialty filter having a different connector structure.

[0003] Some adapters serve purposes other than connection compatibility. There are adapters that are designed to provide added functionality to the respirator. One example of such an adapter is the 3M™ Fit Test Adapter 601 which enables analytical fit testing to be carried out on the respirator by connecting it to a sampling instrument to measure the concentration of a test agent inside the respirator in order to

[0004] It would be desirable to add functionality to a respirator through the use of adapters that are easy to install and easy for a user to operate.SUMMARY

[0005] The present disclosure provides a respirator filter adapter, comprising: a main body having a rear-facing side configured to be connectable to an air inlet of a respirator, and a front-facing side configured to be connectable to an outlet of a filter, and an opening extending through the main body from the front-facing side to the rear-facing side; a lid arranged over the opening on the front-facing side of the main body, wherein the lid is movable between an open position in which the lid is spaced apart from the opening to permit air to flow through the opening, and a close position in which the lid covers the opening to prevent air from flowing through the opening; a spring element arranged under the lid, wherein the spring element biases the lid towards the open position by default when no external force is applied on the lid, and the spring element is responsive to an external force selectively applied on the lid by permitting the lid to be temporarily actuated to the close position.

[0006] In another aspect, the present disclosure provides a respirator assembly, comprising: a filter, a respirator, and a seal checking device comprising a respirator filter adapter as described herein, wherein the respirator filter adapter is connected between an outlet of the filter and an air inlet of the respirator.

[0007] In a further aspect, the present disclosure provides a method of carrying out a seal checking procedure on a respirator, comprising: providing a user with a respirator assembly as described herein, contacting the fdter to apply a force on the lid of the respirator fdter adapter, said force actuating the lid into a close position in which the lid prevents air from flowing through the opening of the respirator fdter adapter, inhaling while air is prevented from flowing through the opening of the respirator fdter adapter, and determining the quality of air seal in the respirator assembly.

[0008] The present invention accords reusable respirators that do not have any dedicated seal checking mechanism with an added functionality of effective seal checking by installing an adapter in between the fdter and the respirator. The adapter operates as a valve that can be selectively closed by a user when it is desired to perform a seal check procedure on the respirator to ascertain the serviceability of the respirator. Advantageously, the adapter is designed to reside directly underneath the fdter when installed, so that it can be readily operated by manually pressing on the fdter to actuate the lid of the adapter in order to close the air inlet of the respirator. The adapter is mechanically simple and is removable for cleaning and replaceable when broken. Through the use of a spring element, the adapter is kept open by default, avoiding any risk of accidental closure of the air inlet.

[0009] From the perspective of users of existing respirators that already have seal checking functionality built in, the present adapter may also provide a more effective way of performing the seal checking procedure. Reusable respirators commercially available as 3M™ Half Facepiece Reusable Respirator Assembly models number 6100 / 6200 / 6300, which utilize non-rigid, series disk type fdters such as 3 M™ Particulate Filters 2091 / 07000, or Filter 2071, P95 or 3 M™ Particulate Cartridge 2076HF may benefit from the use of such an adapter. This list of suitable adaptors and fdters is a non-exhaustive listing, other models may also be fitted with the adapter of this disclosure. In series disk type fdters which are used in dual facepieces, since the fdter is mounted directly on the inhalation ports, users perform negative fit checking by pressing the front of the fdters mounted on the facepiece with their palms to block the air inlet. The present invention enhances the existing method of closure by providing a touch-identifiable button underneath the fdter, designed to fit the air inlet, so that less effort is required of the user in locating the air inlet, and in keeping the air inlet closed. Aside from seal checking, it has been presently found that the adapter can also help to reduce the pressure drop across the fdter during normal breathing. Measurements presented herein found that when the user inhales in a normal filterrespirator configuration, the fdter layer on the front of the disk fdter is sucked towards the air inlet of the respirator due to the inhalation suction force generated at the air inlet, and this occludes the air inlet. When this occurs, the breathable surface of the fdter is reduced to the area immediately around the air inlet, instead of the entire exposed surface of the fdter as is intended. The reduced breathable surface may result in increased breathing effort, causing discomfort in breathing. The adapter can help to alleviate this problem by functioning as a spacer which protrudes into the internal space of the fdter with a headspace imposed by the height of the lid in the open position. The lid of the adapter pushesthe filter layer outwards from underneath, preventing the problem of the filter layer collapsing onto the air inlet during inhalation.

[0010] In an embodiment, the main body comprises an outer grip ring, a flange extending from an inside of the outer grip ring to connect to a first inner ring and a second inner ring, the first inner ring extending axially from the flange towards the front-facing side of the main body, and the second inner ring extending axially from the flange towards the rear-facing side of the main body. The flange provides a contact surface for placing a gasket for air-tight contact with the filter and / or respirator. The first inner ring and the second inner ring may bear connector features for fastening to, respectively, the filter and the respirator.

[0011] In an embodiment, the respirator filter adapter further comprises a gasket arranged on the flange at the front-facing side of the main body between the first inner ring and the outer grip ring.

[0012] In an embodiment, the front-facing side of the main body comprises a first connector arranged on the first inner ring, said first connector configured to be connectable to the respirator filter, and the rear-facing side of the main body comprises a second connector arranged on the second inner ring, said second connector configured to be connectable to the air inlet of the respirator.

[0013] In an embodiment, the first and second connectors are each independently selected from a bayonet connector, a screw thread connector and a snap-fit connector.

[0014] In an embodiment, the lid is configured to shut the opening through an external force applied in a direction moving towards the wearer.

[0015] In an embodiment, the spring element comprises a compressible coil spring or elastomeric material arranged under the lid and having a spring constant of between 10 to 50 N / m.

[0016] In an embodiment, the spring element has a base end supported on a frame arranged across the opening.

[0017] In an embodiment, the lid comprises two or more legs extending from an edge portion under the lid into the opening to slidably engage the main body as the lid moves between the open position and closed position.

[0018] In an embodiment, the lid further comprises two or more legs extending from a central portion under the lid into the opening to slidably engage the main body as the lid moves between the open position and closed position, said legs forming a holder for fastening the spring element to the lid.

[0019] In an embodiment, the legs comprise a claw configured to engage a retaining feature defined either in sidewalls surrounding the opening or on a frame supporting the spring element when the lid is at a maximum permitted displacement in the open position.

[0020] In an embodiment, the movable distance of the lid between the close position and the open position at the maximum displacement is at least 3 mm.

[0021] In an embodiment, in the open position, the lid is spaced apart from an entrance of the opening on the front-facing side of the main body, and in the closed position, the lid makes sealing contact with the main body around the entrance of the opening.

[0022] In an embodiment, the adapter is connected to a filter.

[0023] In an embodiment, when the lid is in the open position, the lid protrudes into an intra-filter space of the fdter thereby pushing the fdter outwards from underneath.

[0024] In an embodiment, the adapter is connected to the air inlet of a respirator.

[0025] These and other advantages of the invention are more fully shown and described in the drawings and detailed description of this invention, where like reference numerals are used to represent similar parts. It is to be understood, however, that the drawings and description are for the purposes of illustration only and should not be read in a manner that would unduly limit the scope of this invention.GLOSSARY

[0026] The terms set forth below will have their meanings as defined:

[0027] “adapter” refers to a n intermediary device connected between a respirator and a filter, which may be either mutually connectable or not connectable;

[0028] “main body” refers to the core structure of the;

[0029] “lid" refers to the structure for shutting the opening;

[0030] “opening” refers to one or more passageways in the main body of the adapter through which air is channeled from the filter to the respirator;

[0031] “spring element” refers to a biasing component capable of undergoing tensile or compressive stress;

[0032] “seal check” means the procedure used to evaluate the overall quality of air seal between a respirator and a wearer’s face. The term “fit check” or “fit checker” sometimes referred to in the art means the procedure or device used to evaluate the fit between a respirator and a wearer’s face. The term “seal check” as used herein encompasses not only factors assessed in a fit check procedure, but also all other factors which affect air seal in the respirator, such as mounting holes through the respirator facepiece, inter-component air gaps and cracks or tears therein which may result in air leakage. Correspondingly, “fit check” as referred to in the art evaluates face fit but does not necessarily provide a broader evaluation as contemplated in a “seal check” procedure as defined herein.

[0033] The figures and the detailed description, which follow, more particularly exemplify illustrative embodiments.BRIEF DESCRIPTION OF DRAWINGS

[0034] The disclosure may be further explained with reference to the appended figures, wherein like structure is referred to by like numerals throughout the several views, and wherein:

[0035] FIG.1 is a side perspective view of a respirator filter adapter in an open position according to a first embodiment.

[0036] FIG.2 is a side perspective view of the adapter in a close position.

[0037] FIG.3 is a top perspective view of the adapter in an open position.

[0038] FIG. 4 is top perspective view of the main body of the adapter.

[0039] Fig. 5 is a bottom perspective view of the main body of the adapter.

[0040] Fig. 6 is a side plane view and bottom perspective view of different embodiments of a lid of the adapter in which legs extend from an edge of the lid.

[0041] FIG. 7 is a side plane view of a lid in which legs extend from a central location of the lid to form a holder for a spring element.

[0042] FIG. 8 is a side plane view of an adapter according to a second embodiment.

[0043] FIG. 9 is a side plane view of an adapter according to a third embodiment.

[0044] FIG. 10 is photograph of a teardown of a fdter with and without adapter attached.

[0045] FIG. 11 is a table of experimental data.

[0046] FIG. 12 a graph of the experimental data, measuring inhalation pressure drop in a fdter fitted with an adapter in which the lid is set to provide opening sizes of between 1 mm to 10 mm.

[0047] FIG. 13 is a bottom perspective view of another embodiment of the adapter body.

[0048] FIG. 14 is a cross-sectional view showing how the second connectors are connected to a respirator with a male bayonet-style connector.DETAILED DESCRIPTION

[0049] In describing preferred embodiments of the invention, specific terminology is used for the sake of clarity. The invention, however, is not intended to be limited to the specific terms so selected, and it is to be understood that each term so selected includes all technical equivalents that operate similarly. The seal check device as described in the following embodiments is not limited to be used for any particular type of seal check procedure and can be used to seal the air inlet or outlet of the respirator. Embodiments described herein in relation to either negative or positive pressure seal check procedures are purely exemplary in nature.

[0050] FIG. 1 and FIG. 2 are a perspective views of a respirator filter adapter 10 comprising a main body 20 having a rear-facing side 201 configured to be connectable to an air inlet of a respirator, and a front-facing side 202 configured to be connectable to an outlet of a filter. An opening 203 extends through the main body from the front-facing side 202 to the rear-facing side 201. The opening 203 may be located at the center of the main body 20, or in other embodiments, it may be located around the edge of the main body 20, or midway between the edge and the center, or a combination thereof. A lid 30 configured to shut the opening 203 is arranged on the front-facing side 202 of the main body 20. Lid 30 is movable between an open position in which the lid permits air to flow through the opening 203, and a close position in which the lid 30 shuts the opening 203 and prevents air from flowing through the opening as shown in FIG. 2. The close position is achieved by applying an external force depicted as arrow 117, generally in a direction moving towards the wearer of the respirator mask. In the open position, the lid is spaced apart from the entrance of opening 203, with a separation height H asindicated by arrow H, (also indicated in FIG. 8 and 9) whereas in the closed position, the lid makes sealing contact with the main body around the entrance of the opening 203. A spring element 40 is arranged under the lid 30 to bias it towards the open position by default to maintain the separation height H. To ensure good sealing between fdter and adapter, a gasket may be provided. A gasket 50 may be arranged on the flange at the front-facing side of the main body between the first inner ring and the outer grip ring. The gasket may comprise any conventional seal forming material, depending on the specific application and requirements. Examples include rubber gaskets incorporating materials such as neoprene, nitrile, EPDM, and silicone. Cork gaskets which are known for their compressibility, resilience, and resistance to oil and fuel may also be used. Polytetrafluoroethylene (PTFE) gaskets, commonly known as Teflon gaskets, are resistant to chemicals, high temperatures, and have low friction properties, may be used as well.

[0051] In order to provide better grip for improved handling, connection capability and sealing contact with the filter and respirator, and overall mechanical strength for withstand regular use, the main body is preferably configured to have a multi-ring structure, in which the main body comprises an outer grip ring, a flange extending radially inwards from the outer grip ring to connect to a first inner ring, the first inner ring extending axially from the flange towards the front-facing side of the main body, and a second inner ring extending axially from the flange towards the rear-facing side of the main body. Explaining in greater detail, FIG. 2 shows a main body 20 of the adapter comprising an outer grip ring21, provided with a plurality of indentations 215 around the external portion of the outer grip ring for better handling. First inner ring 22 is cylindrical in shape and surrounds the central opening 203. First connectors are depicted as male bayonet style connectors 221 and are provided to enable connection with a filter with interlocking female bayonet style connectors. Second inner ring 23 is on the rearfacing side of the main body 20 and comprises a second connector arranged on the second inner ring, said second connector configured to be connectable to the air inlet of the respirator.

[0052] Referring to the perspective view of the adapter in FIG. 3, the adapter 10 including the main body 20, lid 30, gasket 50 and opening 203 are depicted as regular circular structures. The adapter may be configured into any other shapes as desired, such as elliptical, polygonal, or non-symmetric shapes, as long as the opening is made closable by a correspondingly shaped lid, and the adapter is made connectable to the paired filter and respirator.

[0053] FIG. 4 shows the internal structure of the main body 20 on the front-facing side without the attached lid and gasket. In greater detail, main body 20 comprises outer grip ring 21 and first inner ring22, connected by flange 24, which extends inwards radially from the outer grip ring 21 to connect with the first inner ring 22. The flange 24 may connect to the first inner ring 22 via supports 241 which introduce a gap 242 between the flange 24 and the first inner ring 22. First inner ring 22 extends outwards in an axial direction of the opening from the flange 24 towards the front-facing side of the main body and has first connectors 221 formed on the first inner ring 22. On the rear-facing side of themain body, a second inner ring 23 extends outwards in the axial direction of the opening from the flange 24 towards the rear-facing side of the main body.

[0054] The 3-ring configuration, in which the term “ring” denotes a circular structure, is optional and may be varied according to the connector configuration on the filter and respirator. The ring may be circular, elliptical, square, or rectangular, or polygonal. In FIG. 5, the second inner ring 23 has a larger diameter than the first inner ring and is thus configured on a separate ring from the first inner ring 22. If it is of the same diameter, it may be possible to eliminate the second inner ring 23 and replacing it with a first inner ring which extends in the axial direction of the opening from the flange towards both the front-facing side and the rear-facing side of the main body. Second connectors 231 are arranged on the second inner ring 23 and configured to be connectable to the air inlet of the respirator. Second connectors 231 are depicted as bayonet style female connectors and are provided to enable connection with a respirator with interlocking bayonet style male connectors. Other connector types may be implemented as desired. In general, the first and second connectors may be independently selected from a bayonet connector, a screw thread connector and a snap-fit connector. As shown in FIG. 4 and FIG. 5, the connectors are respectively male and female bayonet style connects. It is contemplated that the connectors can also comprise a combination of bayonet and screw thread connectors, or snap-fit and bayonet connectors, or screw thread and snap-fit connectors, and so on.

[0055] A spring element 40 arranged under the lid biases the lid towards the open position by default. The spring element is responsive to an external force selectively applied thereon to permit the lid to be temporarily actuated to the close position under compressive or extensive tensile force. In other words, the spring element is selected to be capable of being either elongated or compressed, i.e. it can be put under an externally applied tensile stress or compression stress, so that when the external force is removed, the spring element biases the lid back towards the open position. In an embodiment, the spring element comprises a compressible coil spring. In an alternate embodiment, the spring element comprises an elastomeric material. The spring element may generally have a spring constant of between 10 and 100 N / m, or preferably between 10 and 50 N / m, or more preferably between 20 and 30 N / m. By way of comparison, some electrical push button switches require a force of less than 10 N to actuate, in some cases less than 7 N, over a distance of 10 mm or less. For a respirator, the force used is preferably less than that of an electrical switch, given that the force is exerted on the facial region. On the other hand, the spring element should possess sufficient strength to prevent any inadvertent closure of the adapter. A rigid spring element may cause difficulty in operation and may also cause premature breakage of the spring element supports, whereas a soft spring element may be more easily actuated but may be actuated accidentally by a user and impart a sensation of looseness. Preferably, the spring element is selected to have a spring specification falling between the two extremes. In a non-limiting example, the spring element is a compression spring having outer diameter (o) 4.2mm(D), 26mm(L) of free length, spring wire thickness (diameter) o 0.4mm(d), 15 effective coils, and material SUS304, ratedat around 7000-7500 kgf / mm2. Using a button pushing force of between 1 N to 10 N, e.g. 4.3N, a suitable spring constant to be used is between 20 to 30 N / m e.g. 22 N / m to 25 N / m.

[0056] In FIG. 5, the spring element 40 is supported on a frame 25 arranged in the opening. As shown in both FIG. 4 and 5, the frame 25 extends across the opening 203 within the first inner ring 22. In this embodiment, the frame 25 is supported by four arms 251 and has a base end 252 to support the spring element. Guiding tabs 254, which may be present in numbers of 2 or more, may engage corresponding slots on the spring housing under the lid (see Fig. 6) to secure the lid to the main body. Any number of arms is possible as long as the arms are of sufficient mechanical strength to resist regular application of forces to close the lid during seal checking.

[0057] FIG. 6 and 7 show possible configurations of the lid 30 in which two or more legs 31 extend from under the lid to slidably engage the main body for the purpose of providing movement guidance for the lid as it moves between the open position and closed position. In FIG. 6 (left figure) one embodiment is shown in which legs 32 extend from an edge portion under the lid. When the lid is inserted into the opening of the adapter, the legs 31 engage the sidewalls of the first inner ring at an angle 0°, where 0° may range from 1° to 15°, preferably 1° to 5°, to ensure that legs 31 abut the walls of the first inner ring with increasing contact pressure. This reduces play which would otherwise cause a sense of looseness as the lid moves towards the opening. By ensuring that there is limited play when the lid 30 moves towards the opening, the accuracy of the lid in closing the opening is also enhanced. Spring housing 33 is centrally arranged to house spring element 40. In FIG. 6 another embodiment (right figure) is shown in which spring housing 33 has a pair of slots 34 defined thereon for receiving guiding tabs on the frame. Slot 34 has a flared opening 341 leading to a circumferential section 342 and ends in an axial section 343. Once guiding tabs 254 are brought into axial section 343, the lid is then able to slide securely between the open and close positions along axial section 343. In FIG. 7, outer legs 31 extend from an edge portion under the lid and inner legs 32 extend from a central region under the lid and are partially connected near the lid, in a circle or other shape concentric, to form a spring holder, similar to the function of the spring housing 33, for securing the spring element 40 to the lid. In a preferred embodiment, each of the inner legs 32 and / or outer legs 31 comprise a claw 327 configured to engage a retaining feature defined either in the first inner ring, or on a frame supporting the spring element, when the lid is at a maximum permitted displacement in the open position. The spring housing 33 may alternatively comprise a central shaft which is inserted into the coil spring, as illustrated in FIG. 8.

[0058] FIG. 8 shows a cross sectional view of an adapter 200 having main body 220 in which outer legs 231 are inserted into the opening 203. Outer legs 231 each comprise a terminal claw 2317 which, when the lid is at maximum displacement H from the opening, engages a retaining rim 2227 located on the inner edge of the first inner ring 222, preventing the lid 230 from sliding out any further. Lid 230 also comprises a central shaft 237, rather than a spring housing, which is inserted through compression spring 240. The central shaft 237, working in conjunction with the outer legs 231, helps to ensure securepositioning of the lid in the default open position, and limited movement of the lid between the open and close positions. The frame 325 has a perforated spring seat 2252 to support the spring element 340 at its bottom end and which receives the central shaft 237.

[0059] FIG. 9 shows another embodiment of an adapter 300 in which lid 330 has outer legs 331 which do not have a terminal claw, so that correspondingly, the first inner ring 322 does not have a retaining rim to catch the terminal claw. Instead, lid 330 comprises an additional set of inner legs 332. The inner legs 332 are inserted into the opening 3321 surrounded by frame 325. Each of the inner legs comprise a terminal claw 3327 which, when the lid is at maximum displacement H from the opening, engages a retaining rim 3257 located on the inner edge of frame 325 which supports the spring element 340. This prevents the lid 230 from sliding out any further once it reaches the maximum allowed displacement H. The frame 325 has anon-perforated spring seat 3252 to support the spring element 340 at its bottom end.

[0060] The specifications of the spring element are not particularly limited. It is preferably of sufficient length and tensile strength to abut the lid and keep it at a position of the maximum displacement H by default. The length of the spring element may be designed to be larger than displacement H, which will ensure that the spring is under constant compressive stress when installed in order to keep the lid firmly biased towards the open position. In preferred embodiments, H is at least 3mm, preferably 3.5mm, 5mm, 7mm, 10mm, or larger. It has been presently found that generally, the larger the value of H, the lower the pressure drop during inhalation, and thus the easier it is to inhale with the adapter fitted. A larger gap permits a larger volume of air flow through the adapter per unit suction force, reducing inhalation effort. In addition, when the lid is in the open position, it protrudes into the intra-filter space within the filter, pushing the filter outwards from underneath, as shown in FIG. 10, in which the arrow S represents the spaced-apart state of the layers of the filter. This maintains a physical separation between the topside filter layers from the opening, which helps to prevent the filter layer getting sucked towards the opening causing the air inlet of the respirator to be occluded during inhalation. The experiments below illustrate the beneficial effect of the spacer on pressure drop across the filter during inhalation.EXAMPLES

[0061] Hereinafter, the adapter will be described in more detail with reference to examples.

[0062] In order to evaluate the effect of the adapter on inhalation and handling, tests were performed on different filters fitted onto 3M™ half facepiece respirators with adapters having a structure according to FIG. 1. To study inhalation impact, in particular the effect of displacement H, the adapter lid was set at varying lid displacements wherein H ranges from 1 mm to 10 mm in increments of 1 mm. Filters evaluated in this experiment are shown in the Table below and in FIG. 11. User tactile feedback to the presence of an adapter in the filter was recorded by the inventors.

[0063] To establish the control (PDo), each filter above was tested for pressure drop without an adapter using the conditions and instrumentation specified in 42 CFR Part 84 (CFR, 2002). For example, for 2071, the PDo reading was 9.3 mm H2O. Subsequently, each filter was fitted with an adapter with lid opening distance (H) set at 1 mm and tested for pressure drop. The same procedure was repeated with adapters with lid opening distance from 2 mm to 10 mm. The pressure drop in each filter with each adapter fitted was noted as “PD (Filter + adapter)”. Then the change in pressure drop compared to the control PDo was calculated as a percentage of change over PDo was calculated for each lid opening distance (H). This yielded “PD change % (vs. control)”. The obtained values are tabulated in the table in FIG. 11, and the values were graphically illustrated in FIG. 12.

[0064] The following observations were made regarding the graphical results of the test.

[0065] Pressure drop improvements were observed in all filters fitted with the adapter as compared to the control. Pressure drop improvements of over 5% were regarded as an improvement over the control. It was observed that pressure drop decreased (improved) as the lid opening distance was increased up to 10 mm. It is thought that the pressure drop decrease will level off and stay constant at a lid opening distance of 15 mm, or 20 mm or up to 25 mm or 30 mm. This is because at higher lid opening distances, opening size is no longer the limiting factor controlling air flow rate but other factors, such as the sizeof adapter opening 203, or the filter size, becomes the limiting factor for air flow rate.

[0066] Overall user tactile experience on the installed adapter was evaluated based on the subjective response of the inventors. Lid opening distance (H) between 4 mm and 10 mm lid opening distance was evaluated, and was found to be acceptable between 5 mm and 9 mm, and optimal between 6 mm and 8 mm. At increasing lid opening distances, actuation of the lid over a longer distance to shut theadapter in a fit test procedure required more effort, whereas at smaller lid opening distances, pressure drop became undesirable, although pressure drop remains the more significant factor.

[0067] Convenience of connecting the filter decreased as lid opening distance increased. This was due to the increasing difficulty of placing the filter over an increasingly protruding lid of the adapter, making it more cumbersome to fasten the connector of the filter onto the connector of the adapter.

[0068] The adapter may be offered individually, or as a filter-adapter assembly in which the adapter is pre-connected to the filter. Alternatively, the adapter may be offered as a respirator - adapter assembly in which the adapter is pre-connected to respirator. The adapter may also be offered fitted together with both a filter and a respirator as a complete respirator-adapter-filter assembly.

[0069] In another aspect a respirator assembly is provided, comprising: a filter, a respirator, and a seal checking device comprising a respirator filter adapter presently disclosed, said respirator filter adapter being connected between an outlet of the filter and an air inlet of the respirator. The adapter may be made available as a convenient retrofitting component for existing respirators, or according to this aspect, the respirator-adapter-filter assembly may be made available in new respirator offerings. In both cases, when fitted, the adapter enables users to carry out a seal checking procedure on the respirator assembly by a user.

[0070] A method of carrying out a seal checking procedure on a respirator is also provided here. A user is provided with a respirator assembly as presently disclosed, with filter, respirator connected. When it is desired to perform a negative pressure seal check procedure, the user, with respirator on, contacts the filter to apply a force on the lid of the respirator filter adapter located underneath. The force actuates the lid into a close position in which the lid covers the opening and prevents air from flowing through. Inhalation is then done by the user while air is prevented from flowing through the opening of the respirator filter adapter. Finally, the user assesses the quality of air seal in the respirator assembly with the lid in the close position. If the respirator and the seal between the user’s face and the respirator is in good condition, the inhalation will draw hardly any air into the respirator. On the other hand, if the respirator is faulty or if the seal between the user’s face and the respirator is in poor condition, the inhalation will draw some air into the respirator, giving the user an indication that the respirator is not serviceable or further evaluation is warranted before use.

[0071] Another embodiment of the adapter body described in Figure 5 is illustrated in FIG. 13 and 14. FIG. 13 provides a bottom perspective view of the adapter in this alternative embodiment, shown from a similar angle as in FIG. 5. Elements in FIG 13 that correspond to those in FIG. 5 are marked with a "b" suffix. For example, reference numeral 21 in FIG. 5 corresponds to 21b in FIG. 13. These elements include variations in shape that are partially or entirely interchangeable. For instance, the outer grip ring 21b is equipped with multiple protrusions (three in Figure 13) extending outwardly, making it easier for the users to turn by hand. The frame 25b is supported by three arms. The base end 252b has a shape that more covers the spring element 40b. A stopper-function second connector 232 is an element not present in FIG. 5. In FIG. 13, as an example, there are two second connectors 23 lb and one stopper-function second connector 232. The number and ratio of these connectors are variable. For instance, all second connectors may be the stopper-function second connector 232, without the second connector 23 lb. The differences between the second connectors 23 lb and 232 are explained in FIG. 14.

[0072] FIG. 14 is a cross-sectional view illustrating how the second connectors 231 / 23 lb or the stopper-function second connector 232 is connected to a lug of a male bayonet-style connector of the respirator (L). FIG. 14(a) represents the case of the second connector 23 lb, while FIG. 14(b) represents the case of the stopper-function second connector 232. In FIG. 14, the upper side with the gasket 50 is the front-facing side, where the inlet of the fdter is connected, and the lower side is the rear-facing side, where the inlet of the respirator is connected. The second connector 231 has a protrusion (23 lb-1) on the side spaced from the gasket 50 (at lower side, rear-facing side). The protrusion 23 lb-1 extends from the rear facing side to the front facing side (from lower to upper). This protrusion 23 lb-1 keeps the male bayonet connector within the internal space (23 lb-2) of the second connector 23 lb.

[0073] Conversely, the stopper-function second connector 232 has a protrusion (232-1) on the side close to the gasket 50 (at upper side, front-facing side). The protrusion 232-1 extends from the front facing side to the rear facing side (from upper to lower). The protrusion 232-1 can move vertically upon insertion of the lug of the male bayonet connector L, as shown in the upper diagram of FIG. 14(b). When the fdter is attached to the upper side of the gasket 50 (front-facing side), this action presses the protrusion 232-1 from the back (upper side, front-facing side) through the gasket 50, keeping the lug of the male bayonet connector L within the internal space (232-2) of the second connector 232, and more effectively preventing disconnection from the male bayonet connector on the respirator side, providing a holding force while the fdter is attached. This allows the stopper-function second connector 232 to have a stronger locking capability with the bayonet connector than the second connector 231.

[0074] Various other modifications and adaptations of the invention will be apparent to the person skilled in the art after reading the foregoing disclosure without departing from the spirit and scope of the invention and it is intended that all such modifications and adaptations come within the scope of the appended claims.

Claims

Claims1. A respirator filter adapter, comprising: a main body having a rear-facing side configured to be connectable to an air inlet of a respirator, and a front-facing side configured to be connectable to an outlet of a filter, and an opening extending through the main body from the front-facing side to the rear-facing side; a lid arranged over the opening on the front-facing side of the main body, wherein the lid is movable between an open position in which the lid is spaced apart from the opening to permit air to flow through the opening, and a close position in which the lid covers the opening to prevent air from flowing through the opening; and a spring element arranged under the lid, wherein the spring element biases the lid towards the open position by default when no external force is applied on the lid, and the spring element is responsive to an external force selectively applied on the lid by permitting the lid to be temporarily actuated to the close position.

2. The respirator filter adapter of claim 1, wherein the main body comprises an outer grip ring, a flange extending from an inside of the outer grip ring to connect to a first inner ring and a second inner ring, the first inner ring extending axially from the flange towards the front-facing side of the main body, a second inner ring extending axially from the flange towards the rear-facing side of the main body.

3. The respirator filter adapter of claim 2, further comprising a gasket arranged on the flange at the front-facing side of the main body between the first inner ring and the outer grip ring.

4. The respirator filter adapter of claim 2, wherein the front-facing side of the main body comprises a first connector arranged on the first inner ring, said first connector configured to be connectable to the respirator filter, and the rear-facing side of the main body comprises a second connector arranged on the second inner ring, said second connector configured to be connectable to the air inlet of the respirator.

5. The respirator filter adapter of claim 4, the first and second connectors each being independently selected from a bayonet connector, a screw thread connector and a snap-fit connector.

6. The respirator filter adapter of claim 1, wherein the lid is configured to shut the opening through an external force applied in a direction moving towards the wearer.

7. The respirator filter adapter of claim 6, wherein the spring element comprises a compressible coil spring or elastomeric material arranged under the lid and having a spring constant of between 10 to 50 N / m.

8. The respirator filter adapter of claim 7, wherein the spring element has a base end supported on a frame arranged across the opening9. The respirator filter adapter of claim 1, wherein the lid comprises two or more legs extending from an edge portion under the lid into the opening to slidably engage the main body as the lid moves between the open position and closed position.

10. The respirator filter adapter of claim 9, wherein the lid further comprises two or more legs extending from a central portion under the lid into the opening to slidably engage the main body, said legs forming a holder for fastening the spring element to the lid.

11. The respirator filter adapter of claim 9 or 10, wherein the legs comprise a claw configured to engage a retaining feature defined either in sidewalls surrounding the opening or on a frame supporting the spring element when the lid is at a maximum permitted displacement in the open position.

12. The respirator filter adapter of claim 11, wherein the movable distance of the lid between the close position and the open position at the maximum displacement is at least 3mm.

13. The respirator filter adapter of claim 12, wherein in the open position, the lid is spaced apart from an entrance of the opening on the front-facing side of the main body, and in the closed position, the lid makes sealing contact with the main body around the entrance of the opening.

14. The respirator filter adapter of claim 1, wherein the adapter is connected to a filter.

15. The respirator filter adapter of claim 14, wherein when the lid is in the open position, the lid protrudes into an intra-filter space of the filter thereby pushing the filter outwards from underneath.

16. The respirator filter adapter of claim 1, wherein the adapter is connected to the air inlet of a respirator.

17. A respirator assembly, comprising: a filter, a respirator, and a seal checking device comprising the respirator filter adapter of any of claims 1 to 16, said respirator filter adapter being connected between an outlet of the filter and an air inlet of the respirator.

18. The respirator assembly of Claim 17, wherein the respirator filter adapter is configured to carry out a seal checking procedure on the respirator assembly by a user19. A method of carrying out a seal checking procedure on a respirator, comprising: providing a user with a respirator assembly of Claim 17, contacting the filter to apply a force on the lid of the respirator filter adapter, said force actuating the lid into a close position in which the lid prevents air from flowing through the opening of the respirator filter adapter,inhaling while air is prevented from flowing through the opening of the respirator filter adapter, and assessing the quality of air seal in the respirator assembly.

20. The respirator filter adapter of claim 2, wherein the front-facing side of the main body comprises a first connector arranged on the first inner ring, the first connector configured to be connectable to the respirator filter, and the rear-facing side of the main body comprises a second connector arranged on the second inner ring, the second connector comprising a protrusion that extends from the front facing side to the rear facing side and is pressed from the front facing side by attaching the respirator filter.

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