WO2023110158A1 - Respirator device with a collar - Google Patents

Abstract

There is herein described a collar for a powered air purifying respirator, wherein the collar is configured to be attached to a hood element such that in use the collar and hood prohibit external fluids from entering the hood, the collar comprising: a collar body situated in a plane, wherein the collar body comprises a torus shape, a fluid inlet configured to house a filter element, the fluid inlet providing a pathway to a void configured to house an impeller, an internal fluid pathway taking air from the void, and a fluid outlet configured to outlet the air from the void, wherein the fluid outlet is angled such that air output from the fluid output emerges at an acute angle relative to the plane of the collar body.

Description

RESPIRATOR DEVICE WITH A COLLAR

Field of Invention

The present application is in the field of respirators. Specifically said respirators may be used in settings such as clinical settings such as hospitals, to protect the user from airborne hazards such as pathogens. This application in particular concerns the collar used to attach the hood to, and that is worn by a user.

Background

Personal protective equipment is used in environments in which there are hazards to humans. The personal protective equipment allows a user to move through said environment whilst minimising the risks posed by said hazards. Examples of such environments include hospitals and clinical settings where there are likely to be airborne pathogens. For example, the air in wards containing covid-19 positive patients will likely contain particulates such as aerosols carrying the Covid-19 virus - and thus putting the staff in the ward at risk.

There have been many attempts to develop sufficient personal protective equipment to reduce the risk of the user effectively. However, these solutions either insufficiently alleviate the problem, or produce other problems. For example, many such devices are difficult to wear, heavy, bulky, or make the user's task more difficult. For example, face masks are often used by clinicians but these can be noisy if they are powered devices, or ineffective if they are not. Clinicians often have to speak with the patient and so the noise of the personal protective device can hinder this communication. Therefore, there is a need to provide an effective piece of personal protective equipment that does not induce other problems to the user. In particular, there is a need for a device to be worn on the user's head in order to reduce the risk on breathing in contaminated air containing pathogens or other hazards.

There is also a need to make it easy to remove the device, and to be able to do so without contamination. It may be beneficial for any non-disposable elements to be readily cleanable, and for the device to not be overly bulky.

There is a particular need for the collar to optimise air flow, and for it together with the hood to minimise the noise created by the device. It is advantageous for the collar to be ergonomic. Summary of Invention

Aspects of the invention are set out in the independent claims. Optional features are set out in the dependent claims.

In accordance with a first aspect there is provided a collar for a powered air purifying respirator, wherein the collar is configured to be attached to a hood element such that in use the collar and hood prohibit external fluids from entering the hood, the collar comprising: a collar body situated in a plane, wherein the collar body comprises a torus shape; a fluid inlet configured to house a filter element, the fluid inlet providing a pathway to a void configured to house an impeller; an internal fluid pathway taking air from the void; and a fluid outlet configured to outlet the air from the void; wherein the fluid outlet is angled such that air output from the fluid output emerges at an acute angle relative to the plane of the collar body. This is particularly advantageous. Air emerging at an acute angle addresses tow technical problems - firstly increasing user satisfaction as air is directed away from the nose and eyes of the user - which can be unpleasant. Secondly this reduces dead spots of air flow within the hood. The hood is effectively a cylinder with a head occupying the central portion. The use of an acute angle allows a helical air flow path to be formed around the user's head. The acute angle allows for several turns within the air flow path before reaching the top of the hood. This means air within the whole hood is being moved (and so carbon dioxide cannot build up at such dead spots).

Optionally, the fluid outlet is angled such that air output from the fluid output emerges at an angle of between 25 degrees and a maximum of 60 degrees from the plane of the collar body, preferably wherein said angle is between 35 and 40 degrees, and more preferably wherein said angle is 38 degrees. This range has been found to be particularly advantageous as a lower angle can create turbulence as the air can interact with the collar itself, and a greater angle can cause discomfort for the user. 38 degrees is particularly effective at creating the helix described above.

Optionally, the fluid outlet is angled such that in use air output into the hood forms a helix within the hood and rotates around the hood adjacent to the circumference of the collar body.

In accordance with a second aspect there is provided a collar for a powered air purifying respirator, wherein the collar is configured to be attached to a hood element such that in use the collar and hood prohibit external fluids from entering the hood, the collar comprising: a collar body situated in a plane, wherein the collar body comprises a torus shape, and further wherein the collar body is formed from a bottom half and a top half; a fluid inlet configured to house a filter element, the fluid inlet providing a pathway to a void configured to house an impeller; an internal fluid pathway taking air from the void; and a fluid outlet configured to outlet the air from the void; wherein a proximal end of the internal fluid pathway connected to the void configured to house the impeller is encapsulated in the top half of the collar body. It has been found that this is advantageous in some embodiments as this reduces the angle of the bend in the internal fluid pathway - and therefore reduces drag, and increases the air flow delivered by the air outlet.

Optionally, the proximal end of the internal fluid pathway is directly connected to the void.

Optionally, the proximal end of the internal fluid pathway is entirely within the top half of the collar body. This has been found to be the most advantageous way of minimising bend in the internal fluid pathway.

Optionally, a distal end of the internal fluid pathway is housed in both the top half and bottom half of the collar body. This allows for ease of construction and effective weight distribution to make the collar more ergonomic.

Optionally, the fluid outlet is positioned on the top half of the collar body. This allows the air outlet to form the helix described above.

In accordance with a third aspect there is provided a collar for a powered air purifying respirator, wherein the collar is configured to be attached to a hood element such that in use the collar and hood prohibit external fluids from entering the hood, the collar comprising: a collar body situated in a plane, wherein the collar body comprises a torus shape; a fluid inlet configured to house a filter element, the fluid inlet providing a pathway to a void configured to house an impeller; an internal fluid pathway taking air from the void; and a fluid outlet configured to outlet the air from the void; further comprising a hole configured to house a power cable having a selected diameter, wherein the hole enables access to the void configured to house the impeller, and wherein the hole is sized to be flush with the cable diameter. This may reduce dirt ingress, and also reduce air flow loss, and turbulence.

Optionally, the hole has a diameter of 4mm. This may be a tight fit, whilst not catching the cable, and causing tension that may damage the device.

Optionally, wherein between the hole and the void is a channel that forms a U-bend for the cable to pass through. This reduces movement of the cable and therefore reduces wear on the device.

In accordance with a fourth aspect there is provided a collar for a powered air purifying respirator, wherein the collar is configured to be attached to a hood element such that in use the collar and hood prohibit external fluids from entering the hood, the collar comprising: a collar body situated in a plane, wherein the collar body comprises a torus shape, and further wherein the collar body is formed from a bottom half and a top half; a fluid inlet configured to house a filter element, the fluid inlet providing a pathway to a void configured to house an impeller; an internal fluid pathway taking air from the void; and a fluid outlet configured to outlet the air from the void; wherein the bottom half and the top half of the collar body are joined by a double sided adhesive gasket. This may be particularly advantageous as manufacture has been found to b quicker than using other forms of adhesive such as glue. Moreover, this enables a thinner layer of adhesive to be used, and therefore there is a reduced amount of excess adhesive when the portions are pressed together. This may reduce the capture of detritus.

Optionally, the double sided adhesive gasket is formed from 3M tape.

Optionally, the gasket is coated in an adhesive on both sides.

Optionally, the adhesive is acrylate.

Optionally, the adhesive layer is 0.05mm to 0.1mm thick, preferably wherein the adhesive is 0.076mm thick. It has been found that this thickness provides sufficient strength of bond, whilst minimising excess adhesive.

In accordance with a fifth aspect there is provided a collar for a powered air purifying respirator, wherein the collar is configured to be attached to a hood element such that in use the collar and hood prohibit external fluids from entering the hood, the collar comprising: a collar body situated in a plane, wherein the collar body comprises a torus shape, and further wherein the collar body is formed from a bottom half and a top half; a fluid inlet configured to house a filter element, the fluid inlet providing a pathway to a void configured to house an impeller; an internal fluid pathway taking air from the void; and a fluid outlet configured to outlet the air from the void; the collar body further comprising an indent configured to house an indicator, wherein the indent comprises a groove to mate with an alignment portion on the indicator, wherein the groove is positioned adjacent the join of the top half and bottom half of the collar body. This may allow flexibility in the assembly process a sthe indicator may be placed in either the top or the bottom half - depending on which is easier for the user based on other components.

Optionally, the collar further comprising a collar perpendicular to the groove to align a first edge of the indicator with. This may enable the user to more readily position the indicator accurately.

Optionally, the collar further comprising a second collar perpendicular to the groove and parallel with the first collar to align a second edge of the indicator with. This may enable the user to more readily position the indicator accurately.

Optionally, the indicator is substantially cylindrical and the first and second edges refer to the top and bottom flat surfaces of the cylinder.

Optionally, the torus of the collar body has a diameter of 32mm. This may allow the collar to not be too bulky for use, whilst also being large enough to mitigate the majority of slippage in use.

Optionally, the collar comprises an impeller housed in the void, the impeller configured to provide air flow to the air outlet.

Optionally, the impeller draws air in from the air inlet.

Optionally, the impeller is powered by a 5.1v-5.4v voltage source. This may advantageously provide the required air flow, whilst minimising the noise produced.

Optionally, the collar comprises a filter positioned in the air inlet and positioned on the opposite side of the air inlet than the impeller. Optionally, the collar comprises an indicator to indicate that the air flow out of the impeller is above a predetermined level. This may advantageously indicate if there is a failure and indicate the user should leave the hazardous area immediately.

In accordance with a sixth aspect there is provided an indicator for use with a powered air purifying respirator, the respirator comprising a collar element, and a hood element, wherein the indicator is configured to sit in the collar and monitor the air flow through the collar, and to indicate if the air flow drops below a predetermined level, the indicator comprising: a housing; a rotor blade configured to be driven by air flow, the rotor blade situated within the housing; a spring configured to invert upon exposure to air flow over a predetermined level; wherein the spring is situated within the housing, and is attached to the housing by a hook at the end of the spring connecting to an outdent of the housing. This may make the spring particularly simple to fit into the indicator. This can otherwise be an onerous task in assembly, and so greatly decreases time for manufacture.

Optionally, the hook forms an L-shape, or U-shape around/through the outdent of the housing. This may offer a secure attachment.

In accordance with an eight aspect there is provided an indicator for use with a powered air purifying respirator, the respirator comprising a collar element, and a hood element, wherein the indicator is configured to sit in the collar and monitor the air flow through the collar, and to indicate if the air flow drops below a predetermined level, the indicator comprising: a housing; a rotor blade configured to be driven by air flow, the rotor blade situated within the housing; a spring configured to invert upon exposure to air flow over a predetermined level; wherein the rotor blade is within an inner housing, and further wherein the rotor blade extends the full length of the inner housing whilst rotating 68-78 degrees and preferably 73 degrees. This angular range may be particularly advantageous as the spring flips between positions at a set force. However this is not the same force if it is flipping in one direction to the other. Therefore this angular range may enable the indicator to be in the correct position and not give false negatives due to the difference force thresholds.

In accordance with a ninth aspect there is provided an air purifying respirator comprising the collar of any preceding claim, and a hood, wherein the hood and the collar are configured to be attached.

Optionally, the hood comprises a first aperture for the user's head to pass through.

Optionally, the hood comprises a second aperture positioned adjacent the air inlet of the filter.

Brief Description of Figures

Figure 1 shows a perspective view of a hood to be used with the device.

Figure 2 shows the template for the hood in manufacture.

Figure 3 shows a template for the visor of the hood in manufacture.

Figure 4 shows an exploded view of the components of the collar of the respirator.

Figure 5 shows a plan view of the bottom half of the collar.

Figure 6a shows a cross section of the bottom half of the collar.

Figure 6b shows a further cross section of the bottom half of the collar.

Figure 6C shows a close up of the portion of the collar configured to house the indicator.

Figure 7 shows a perspective view of the bottom half of the collar.

Figure 8a shows a close up of the air outlet from above.

Figure 8b shows a close up of the air outlet in partial cut-away.

Figure 9 shows a plan view of the top half of the collar.

Figure 10a shows a cross section of the top half of the collar.

Figure 10b shows a close up of the portion of the top half of the collar configured to house the indicator.

Figure 11 shows an exploded view of the components of the impeller.

Figure 12a shows a perspective view of the rotating component. Figure 12b shows an exploded view of the rotating component.

Figure 12c shows a plan view of the first disc of the rotating component (the blades may be situated on either disc).

Figure 13a shows a side view of the rotating component.

Figure 13b shows a plan view of the outside of the first disc.

Figure 14 shows both sides of the second disc.

Figure 15 shows a portion of the outer shell with the first air inlet.

Figure 16a shows a cross section of the outer shell of the impeller.

Figure 16b shows various cross sections of Figure 15a showing the widths of the air pathway at various points along the angular rotation of the air pathway.

Figure 17a shows a side view of the outer shell of the impeller.

Figure 17b shows a perspective view of the half of the outer casing without the air inlet.

Figure 18a shows a perspective view of half of the outer shell of the impeller with the first air inlet.

Figure 18b shows a cross section of the impeller.

Figure 18C shows a plan view of the half of the impeller with the air inlet.

Figure 19 shows an exploded view of the indicator.

Figure 20 shows a plan view of the base plate of the indicator.

Figure 21 shows a plan view of the spring of the indicator.

Figure 22a shows a plan view of the axis of the rotor in the indicator.

Figure 22b shows a pattern of the central portion of the axis.

Figure 23a shows a plan view of the rotor of the indicator.

Figure 23b shows a cross section of the rotor showing various cut through.

Figure 23c is a first cut through showing a cross section of the rotor.

Figure 24a shows a plan view along section G-G of Figure 22b.

RECTIFIED SHEET (RULE 91) ISA/EP Figure 24b shows a plan view along section H-H of Figure 22b.

Figure 24c shows a plan view along section I-I of Figure 22b.

Figure 24d shows a plan view along section J-J of Figure 22b.

Figure 25a shows the portion of the rotor that mates with the base plate.

Figure 25b shows this same portion in perspective view.

Figure 26a shows the front of the rotor for attachment to the spring.

Figure 26b shows the front of the rotor for attachment to the spring in perspective view.

Figure 27a shows a perspective view of a cable end with a locking pattern to prevent inadvertent decoupling of the cable from the power source.

Figure 27b shows a plan view of the end of the cable with the locking pattern.

Detailed Description of Figures

Figure 1 shows a hood. The hood comprises a skirt portion 3, a visor portion 2 and a hood body. The hood body comprises two hemispheres separated by a central seam. The central seam may extend to the visor portion 2, or may end (as shown) before the visor portion. The visor portion is free from the central seam. Also shown in Figure 1 are two valves 1. The valves are configured to allow air to be expelled from the hood. The hood may be configured to contain a positive pressure (i.e. the hood may contain air at a pressure above atmospheric or local pressure). Therefore, the valves may allow air to exit from the hood. However, the valves do not allow air to enter into the hood via the valves. The valves may be configured in this manner, or alternatively the valves may be two way valves, and the positive pressure may be sufficient to stop air from entering through the valves during use.

The central seem provides a shape and structure to the hood. The seam may comprise a raised ridge. This may provide structural support to the hood to prevent sagging of the hood. The central seam in some embodiments is punctuated by an air inlet. The air inlet may be positioned at the rear of the device on the opposite side to the visor portion. The air inlet may comprise a reinforced ring to provide stability and to prevent the air inlet from being weakened to cause potential damage to the hood during use.

The valves may be positioned either side of the central seam. In use this creates two portions for air outlets at points air is directed by flow from the air outlet of the collar

RECTIFIED SHEET (RULE 91) ISA/EP This therefore reduces the linger time of air within the hood, which reduces build-up of carbon dioxide. It has been found that having two or more valves is particularly advantageous as one valve provides a single exit point for air. One exit point is not as efficient as two with the same capacity because user movement, or movement of the air flow can reduce the amount of air exiting through a single valve, but is less likely to affect two or more valves in the same way.

Moreover, it is advantageous for the valves to be positioned symmetrically apart from the seam so that air flow is symmetrical around the hood. If one valve is used then either it must be positioned symmetrically (in which case it further weakens the central seam) or it is offset and so creates an unequal distribution of air flow. This may create discomfort for the user, increase air linger time within the hood, or increase drag in the air (increasing noise). Therefore, two valves are particularly advantageous.

Figure 1 also shows three connectors at the base of the visor portion. These connectors are for connection to the collar portion of the device. The three connectors comprise a central connector, a right most connector and a left most connector. The connectors provide a secure connection to ensure the hood and collar do not decouple during use, as the user may be in a hazardous environment. The connectors may serve a dual purpose. The central connector in particular may reduce the flex that propagates from the hood body into the visor portion. Flex in the visor portion may cause visual distortions for the user as the flex may change the effective thickness of the visor portion in the user's eye line, and therefore the effect of light travelling a different distance through the material may cause distortion. As the hood may be used for example in surgical procedures visual accuracy is important. The connectors may be manufactured from the same material as the rest of the visor (this may improve the recyclability of the visor), and may be integral to the structure of the visor in order to reduce flex of the visor.

Also shown in Figure 1 are the apron connectors. These are situated in the right hand and left hand corner of the visor portion. These comprise tabs that may be manipulated or folded along a diagonal score line that separates the apron connector from the remainder of the visor portion. The apron connector comprises a slot for an apron (or other PPE item) worn by a user to fit within. This joins the respirator to the other PPE item and therefore combines to form an effective protection. The slot in this particular example has a zig-zag pattern. This zig-zag pattern has been found to be particularly beneficial at restraining an apron strap, and therefore creates a secure attachment. The placement of the apron connector in the corner of the visor portion greatly increases efficiency of manufacture. This is because the apron connector can be formed in a single step with the formation of the visor portion. No welding or other attachment is needed. The visor portion is also not weakened and so no additional visor flex is induced (or minimal additional flex dependent on the exact arrangement). Indeed, the corner can simply be created by scoring or bending the visor portion appropriately rather than any more time consuming, costly or complex technique.

The skirt portion may comprise a side hole. One side hole may be placed on either side of the skirt (either side defined as one side or other of the central seam). These side holes may allow the strap to fit therethrough. The strap may then be used to contain the skirt to remove the skirt from being in the way of any user activity. The side holes shown here each comprise a slot that the strap threads through. This is shown by the rectangular portion over the strap on each side of the skirt. The side holes are beneficial as it is efficient to manufacture. The side holes may be created by stamping the skirt during the cutting of the material for the hood, and therefore add very little time or expense to the manufacture process.

Figure 1 also shows perforations in a score line situated at the rear of the device. This score line may be used to tar the hood along the score line. When the user comes to remove the hood at the end of use there is a technical problem as to how to remove the hood whilst minimising contact between the user (or any other surface) and the outside surface of the hood as the hood may be contaminated. By tearing the score line the hood can simply be lifted off of the collar and so no other surface touches the outside of the hood (aside from a user's hands which should be clad in PPE or gloves). The hood can then be appropriately disposed of. The perforations - and gaps between the perforations are of a certain size to make tearing simple for a user. These sizes are shown in Figure 2. However, it has been found that having the perforations longer than the gaps between the perforations is advantageous in making the tearing easy enough for a user - even when fully clad in PPE.

There is also an annular contact portion situated below the connectors at the top of the skirt portion. The annular contact portion is an annulus that is configured to come into contact with the collar of the device when the respirator is in use. The annular contact region is the ring that forms a seal with the collar. This seal may be one of two types. Firstly, the seal formed between the annular contact ring and the collar may be airtight. This means that no air can enter or exit the hood via the seal between the hood and the collar. This can be achieved by having a close fit between the hood and the collar. In some instances, the annular contact portion may be formed of a ring of hardened, or thicker material (potentially even rigid material in some instances) that fits around the collar. This may be a friction fit or there may be a snap fit, or other mechanical fit at this point. In this example however the annular contact portion is simply a ring of material that contacts the collar - and is not physically different to regions around it. This is because a positive pressure seal is used. This means that air can exit between the hood and the collar, but it cannot enter the hood in this way. This is because of the higher pressure within the hood. This therefore requires a looser fit between the annular contact region and the collar. What is important in this embodiment however (and to an extent in the airtight embodiment too) is that the connectors shown are situated to be offset from the annular contact region. This means that the connectors (and the bulging structure that facilitates them) does not interfere with the seal created at the annular contact region. This therefore improves the seal, and means that less air can travel between the hood and outside of the hood. This offset may ideally be 6 mm (as this provides a sufficient distance to create an improved seal). However, the offset may be in the range of 2- 20mm to get at least a portion of this effect. The 6mm offset may be more ergonomic for use, as no part of the user's view may be obstructed by the connector.

Figure 2 shows a template used in the manufacture of the hood. On the left hand side is a zoomed in view of the perforations showing that the perforations in the score line are 5.5mm long, and the gaps between the perforations are 3mm long. The perforations are therefore longer than the gap between the perforations. The perforations may be any length between 5mm and 6mm. The tear strength needed to tear these perforations varies between 15N and 30N dependent on the exact length of the perforations. It is noted that handles may be added to the hood body adjacent the score line and the perforations, such that the user may grip the handles in order to tear the score line in order to remove the device. This may make the removal of the hood easier for the user as the handles may be easier to grasp.

The template shows the visor portion and the hood portion. In this example the apron connectors are not shown. The central seam will be formed by connection the two sides of the hood body together to form an encapsulating hood. It is noted that the hood body and the visor portion may be made from the same material - e.g. PVC in order to make the hood more readily recyclable. In this example the visor portion is made of the same material - but is thicker (around 500 microns in thickness) in order to reduce the flex of the visor portion. The hood body on the other hand has a thickness of 150 microns - and so allows for greater user movement.

A valve hole is also shown either side of the template. The valve hole may be undersized such that it is smaller than the diameter of the valves - so that the seal formed from the valve entering the valve hole is tight. This may mean that no adhesive is required for the valve to be situated correctly. A two-part valve connecting together with the valve whole between the two portions of the valve may allow for such a tight connection.

The air inlet is shown as two hemispherical cut-outs at the periphery of either side of the template. The perforations may be formed adjacent the edge of either or both sides of the hood - below the hemispherical cut-out for the air inlet.

Figure 3 shows a template for the visor portion. This shows the apron connectors and a curved top edge of the visor. This is so that when the visor is bent in use (as shown in Figure 1) the top edge becomes flat. Alternatively, the top edge may be flat or otherwise curved in the template and may be curved during use. This may however complicate the join between the visor and the hood body, which then maybe reinforced. The dimensions of the connectors in this embodiment are also shown - as are the approximate dimensions of the visor itself.

Figure 4 shows an exploded view of the collar (a perspective non-exploded view is also shown for completeness). The collar comprises a top portion, a bottom portion, an impeller, a cable to connect the impeller to a power source, an indicator, connection pins, a weighting element and not shown is a filter element. The top portion and bottom portions are configured to connect together. Together the top portion and bottom potion form a collar body. This is approximately a torus in shape. In some embodiments the diameter of this torus may be 32mm, whilst the diameter of the collar body may have the diameter just greater than a human head (around 30cm). Other sizes may be used. In use the collar body is worn around a user's neck. On the front of the collar body (on the top portion of the collar in this example - but they could be on either portion) are connection points. These three connection points (other number of connection points may be used in other embodiments) may connect to the connectors of the hood to connect the hood and the collar together.

The hood body may be weighted. This is an entirely optional feature. The weighting may provide a more ergonomic weight distribution so that the collar body is front heavy. This means that when a user bends for instance the rear of the collar is not raising the front of the collar body into the user's chin - and so improves the user experience.

The impeller is used to provide air flow into the hood. This air flow is provided through an air pathway situated between (or encapsulated within one or both) of the portions of the collar body. The air is then outlet from an opening (the air outlet) on the top portion of the collar body. The impeller may be any impeller. A particularly effective impeller is described later with respect to later Figures.

The cable passes through a hole in the collar boy. This hole is approximately circular and is 4mm in diameter. This makes the fit between the cable and the hole tight. This reduces dirt ingress and makes cleaning the collar after use simpler. After the cable enters the hole to pass through a U-shaped bend channel before reaching the void that houses the impeller. This U-bend channel may secure the cable in position and prevent the cable from being inadvertently removed from the impeller during use.

An indicator is also shown. This indicator sits in the air flow path and indicates if the air flow drops below a pre-determined level. This level may correspond to an amount of air flow that is safe for a user. Any indicator may be used. A particularly effective indicator in one embodiment is described with reference to later Figures.

The shape of the collar portions is advantageous. The upper portion comprises a bulge to house a void in which the impeller sits. A channel protrudes from this void. This is the air pathway for air exiting the impeller. At the proximal end of the air pathway the air pathway is fully encapsulated within the top portion of the collar body. This then joins the remainder of the air pathway that sits in both the top and bottom portions of the collar boy, before exiting at the air outlet in the top portion of the collar body.

It is noted that the bottom half and the top half of the collar body may be joined in some embodiments by a double sided adhesive gasket. This gasket may replace other adhesive such as glue. The use of the gasket may therefore both simplify manufacture (As the gasket can simply be positioned in place rather than needing to be applied or spread) and may also reduce the amount of excess adhesive used. This reduction may limit detritus adhered to the device, and may aid cleaning. The gasket may be shaped in a ring to match the torus shape of the collar body. The gasket may avoid covering the air pathway situated within the collar body. The double sided adhesive gasket may be formed from 3M tape. The gasket may be coated in an adhesive on both sides. The adhesive may be acrylate. The adhesive layer may be 0.05mm to 0.1mm thick, in particular the adhesive may be 0.076mm thick. This thickness range may be particularly effective t providing the needed adherence, but in limiting the amount of excess adhesive.

Figure 5 shows a plan view of the bottom half of the collar. This shows a space for the indicator (indicated "L"), a space for the impeller, a space for the filter (attached to the impeller), and an air pathway. The impeller is configured to sit in the void within the bottom half of the collar body. The impeller is configured to be attached to the filter. The filter is also configured to sit within the collar body. In particular, the filter sits in the air inlet at the rear of the collar body. The filter feeds the air to the impeller. The impeller therefore draws air in through the air inlet, through the air filter, and then directs the air into the air pathway within the collar body.

The air filter may be any air filter suitable for filtering the air. For example, in a clinical setting the air filter may be suitable for filtering air borne pathogens out of the air.

The air pathway shown in Figure 5 is non-continuous. This is because the air pathway directly connected to the impeller is housed within the upper portion of the collar body (as opposed to the bottom half of the collar body shown in Figure 5). Having the proximal end of the air pathway (connected to the impeller) allows the void in the collar for the impeller to be enlarged to accept a larger impeller (with the associated higher air flow).

Wings are also shown at the rear of the collar body These wings protect the air filter (and to an extent the impeller) from any knocks or forces as a user collides into other objects. The wings are shaped to be triangular (although this is not essential), and the vertices and edge of the wings may be atraumatic in some embodiments.

The air flow path then re-appears in this bottom half of the collar body. The indicator sits in the air flow path. As shown in figure 5 a groove in the collar body adjacent the top surface of the bottom of the collar body (i.e. adjacent the point at which the bottom half will join to the top half) comprises an indent configured to accept an alignment nodule of the indicator. The position of this means that the indicator may be put into either the top or bottom half of the collar body during assembly, making the assembly of the collar more flexible. Collars may also be situated within the collar body at the point at which the indicator may be positioned. These collars may aide the alignment of the indicator when the collar is being assembled.

Figure 6a shows a cross section of the bottom half of the collar. This viewpoint is from the rear of the collar body. This shows the air inlet and the position at which the filter will sit from a rear view.

Figure 6b shows a further cross section of the bottom half of the collar. This shows that the rear portion and front portion of the bottom half of the collar body are deeper than the central portion. This is because impeller is at the rear portion of the bottom half of the collar body. The front is deeper to accommodate the weighting element positioned at the front of the bottom half of the collar body. Figure 6C shows a close up of the portion of the collar configured to house the indicator. This shows the cavity in which the indicator is configured to sit. The two collars at the edge of the cavity are shown. This helps guide the assembly of the indicator within the collar body. Also shown is a groove at the top surface of the bottom half of the collar for accepting an outdent of the indicator.

Figure 7 shows a perspective view of the bottom half of the collar. In this example the weighting element is positioned in the bottom half of the collar, and so the depth of the front portion of the collar is expanded. The void for the impeller, and the air flow path described above are also shown.

Figure 8a shows a close up of the air outlet from above. This is positioned on the top surface of the top half of the collar body. The front of the collar body is shown at the point at which the central connection (which is extending from the torus). The air outlet is positioned offset from the front of collar body. This means that air is angled away from the user's nose and mouth. This decreases user discomfort whilst using the device. In this example the air outlet is positioned 20 degrees to 40 degrees along the torus away from the front of the collar body. In particular, this offset is 30 degrees. In distance this offset is approximately 30 mm from the centre of the torus. This also helps create a helix of air around the user's head as air flow straight from the air outlet is not impeded by the user's facial features.

Figure 8b shows a close up of the air outlet in partial cut-away. This shows that the outlet is angled at an angle from the plane of the collar body. The air outlet is angled at 38 degrees in this example. However, a range of between 25 to 60 degrees, and more preferably 30 to 45 degrees may be used. 38 degrees has been found to be the optimal angle. This angle (and the associated ranges) are angled acutely so that air does not blow up into a user's face. Instead air blows (at least partially) across so that the air forms a helical flow path around the user's face within the hood. The hood is relatively cylindrical so the volume around the user's head permits air flow. By increasing the number of turns in a helical air flow path around the user's head this decreases the number (or proportion) of dead spots within the hood. Dead spots may have little or lower air flow, and so carbon dioxide may gather there. Increasing the number of turns in the helix by reducing the angle eradicates at least some of these dead spots, and therefore promotes a high turnover of air within the hood. However, if the angle is too low then air will interact with the collar itself, and turbulence will therefore be created. The range of angles (and 38 degrees in particular) has been found to balance these concerns. Figure 9 shows a plan view of the top half of the collar. This is almost a mirror image of the plan of the bottom half of the collar. The portion for the indicator for the instance is the same as the bottom half, allowing flexibility as to which portion of the collar the indicator is first placed in to during assembly.

The main difference concerns the portion of the air pathway connected to the void configured to house the impeller. A fully encapsulated channel exists between this void and the visible section of the air pathway that can be seen.

Figure 10a shows a cross section of the top half of the collar. This cross section shows not just a bulbous portion for hosing the void to house the impeller, but also an elongate extremity extending from this void. This is the fully encapsulated section of the air pathway that is directly connected to the void housing the impeller. In this section air only flows through the top portion of the collar. When the air flow path reaches the point on both Figure 9 and Figure 5 where the air flow path can be seen the air flow path is then in both the top and the bottom portions of the collar body.

Figure 10b shows a close up of the portion of the top half of the collar configured to house the indicator. This is identical to Figure 6b, with the exception that the air outlet is positons next to the indicator.

Figure 11 shows an exploded view of the components of the impeller. The impeller comprises a cable for providing power to a motor, a motor, a washer, an outer shell comprising a first portion adjacent the motor and a second portion, and a rotating component. The second portion of the outer shell comprises a first air inlet. A second air inlet is situated on the rotating component adjacent the first air inlet. The rotating component sits within the outer shell. The outer shell also comprises an air outlet, which is perpendicular to the first air inlet and the second air inlet.

The motor may be any suitable motor for rotating the rotating component. The motor may however transmit vibrations to the rotating component. Therefore, the washer may in some embodiments damp these vibrations effectively. In some embodiments the washer may be housed in an indent positioned on the outside of the second disc around the hole for the motor to access through the outer shell. In some preferable embodiments the washer may have a greater depth than the indent such that the motor, washer outer shell assembly must be overtightened to get the arrangement flush at the outer shell. This may damp vibrations particularly effectively. The washer r may in some embodiments be softer in hardness than the outer shell so as to not damage the outer shell. For example, the washer may have a hardness between 50D and 70D, and in particular may be 55D. The washer is however entirely optional. Figure 12a shows a perspective view of the rotating component. This shows that the rotating component comprises a first disc, a second disc, and blades sandwiched there between. The sides of the rotating component are open. The rotating component forms a cylinder whereby the base is significantly wider in diameter than the cylinder is long in length.

Figure 12b shows an exploded view of the rotating component. This shows that the blades are attached to the first disc of the rotating element, and that the first disc comprises the second air inlet, configured to feed air into the rotating component.

It is noted however that the blades may alternatively be positioned on the second disc (the disc without the air inlet, and the disc that is positioned closet to the motor). Indeed, this arrangement may be highly advantageous. As the blades are then attached to the second disc this is the disc that is directly connected to the shaft that receives drive from the motor. Therefore, the second disc is exposed to vibrations of the motor. The blades being attached to the second disc advantageously may damp the vibrations transmitted from the motor, and therefore ensure more even rotation, and less vibration, and therefore a greater produced air flow, and less turbulence within the air flow created. In such embodiments a washer may not be used.

The air inlet of the rotating component comprises a rounded entry. This rounded edge may lessen the drag of the air entering the rotating component. This rounded edge may comprise a tapered edge tapering from the outside edge of the first disc to the inside edge of the first disc. The rounded edge may avoid sharp edges that may create turbulence. The rounded edge may comprise a rounded fillet. Said fillet may be formed in the injection moulding process as a single piece with the remainder of the first disc. Alternatively the fillet may be added after the first disc is formed.

Figure 12c shows a plan view of the first disc of the rotating component (the blades may be situated on either disc). It is noted that in this embodiment the disc has 13 blades attached thereto. In this embodiment this number of blades has been found to be advantageous in the efficient creation of air flow. It is also noted that the blades are equidistant. This may be the case even if the number of blades is changed.

The blades themselves are approximately 1.5mm in length for the majority of the length of the blade. At the distal end (that end closest the circumference of the disc) the blades may be slightly flared. At the proximal end (that nearest the air inlet) the blades are shaped to be rounded at the end. The blades in some embodiments are atraumatic. This reduces the turbulence caused when the air flow from the air inlet hits the proximal end of the blades. In some embodiments the proximal end of the blades may be shaped as an aerofoil with one side of the proximal end of the blade having a longer air flow path than the other side of the blade. This therefore creates an imbalance in the air flow either side of the aerofoil. This may also reduce turbulence formed as air progresses along the blade, as the air may act as a single sheet between each blade, with minimal turbulence.

Four blades are shown highlighted with black. This is because these blades have a fusion element along the spine of the blade. The spine of the blade may be defined as the longitudinal line in the centre of the blade. These spine protrusions may help the blades be fused to the second disc (or to the first disc if the blades are already positioned on the first disc). It is noted that every blade may comprise such a protrusion. In this embodiment the protrusions are evenly spaced and four blades with protrusions are present.

The curve of the blades creates a backward curved spiral which has been found to generate efficient air flow. Moreover, in the viewpoint shown in this figure (viewing from between the first and second disc through the air inlet of the first disc) the rotating component is configured to rotate counter clockwise. This has been found in combination with the backward spiral, to be particularly efficient at air flow generation.

It is noted that the depth of the rotating component may be less than the depth of the void within the outer shell. In particular, the depth of the rotating component may be 5m less than the depth of the void. This may reduce any contact between the rotating component and the outer shell (which may create noise, and reduce air flow) and may also provide a vertical space for the air to exit the rotating component, and therefore reduce turbulence as the exiting air ions the air flow pathway around the rotating component.

The curve of each blade is shown in graph 1.

RECTIFIED SHEET (RULE 91) ISA/EP This graph shows that the curve of the blade may be approximated by a deltoid function, or by a cubic spline fit. This plots the co-ordinates of the centre point of the blade.

Figure 13a shows a side view of the rotating component. This shows that the sides of the rotating component are open. This allows air flow to exit the rotating component via the sides when the impeller is in use.

Figure 13b shows a plan view of the outside of the first disc. This shows the air inlet that is used to draw air into the rotating component.

Figure 14 shows both sides of the second disc. The left most side in the Figure shows the inside of the second disc. This is mostly flat. Four pin holes are situated around the outer edge of the disc. These pin holes may correspond with pins on the inside of the first disc. This pins may be used to align the discs together accurately when the two discs are being fused together. The outside of the second disc is shown in the rightmost part of the Figure. This shows that the central portion of the second disc is configured to be driven by the motor, causing rotation of the rotating component.

Either of the two discs may also comprise a balancing ring. This is a ring of material at a position around the disc (typically on the outer side of the disc). This ring of material may be removed to weight balance the rotating component. Weight balancing ensures that the rotating component is weighted neutrally, and so rotate freely (with an equal weight distribution). Due to manufacturing errors there can be slight unevenness in the weight distribution of the rotating component. The balancing ring can then be trimmed appropriately to remove material at regions where there is additional mass to correct for the errors in manufacture and create a neutrally weighted rotating component.

It is noted that rotation of the rotation component, and use of the impeller as a whole produces noise, but without significant noise in the range of 500Hz to 2000Hz. This is advantageous because other medical equipment and systems use sound in this frequency, and so avoiding this frequency limits any interference between the devices.

Figure 15 shows a portion of the outer shell with the first air inlet. This is the second portion of the outer shell. The air inlet is configured to be attached to the air filter that is also positioned within the collar body. The air passing through the air filter then enters the first air inlet, and then enters the void within the outer shell. This is the void in which the rotating component is housed.

Figure 16a shows a cross section of the outer shell of the impeller. This shows that the outer shell of the impeller comprises a central void in which the rotating component is housed. Around the rotating component is an air pathway. This air pathway starts at a

RECTIFIED SHEET (RULE 91) ISA/EP narrow point (around the cross section B-B as marked). The air pathway then widens as it approaches the air outlet at the end (in a similar manner to the enlarging compartments in a nautilus shell). This widening may be by any amount. In this particular example the width of the channel widens in a linear manner as compared to the radians of rotation (starting from the point B-B). A graph plotting the radians of rotation with respect to the width of the channel is shown in graph 2.

Radians are plotted on the X axis, and the width of the channel on the y axis. The width therefore multiplies by two to three times per doubling of the rotation in radians. Specifically, the width multiplies by 2.25 (and more specifically 2.2263).

Figure 16b shows various cross sections of Figure 15a showing the widths of the air pathway at various points along the angular rotation of the air pathway. This shows the widths of each of the cross sections shown in Figure 16a, and these widths are then plotted on the graph shown above.

Figure 17a shows a side view of the outer shell of the impeller. This shows the air outlet from the outer shell of the impeller.

Figure 17b shows a perspective view of the half of the outer casing without the air inlet.

Figure 18a shows a perspective view of half of the outer shell of the impeller with the first air inlet, inlet This shows that the casing for the air flow path is formed in this half of the outer shell. The air inlet forms a cylindrical inlet that may mate with the air filter such that there is join such that air passes seamlessly from the air filter to the first air inlet. This may reduce turbulence.

Figure 18b shows a plan view of the half of the impeller with the air inlet.

RECTIFIED SHEET (RULE 91) ISA/EP Figure 18c shows a cross section of the impeller. This shows the first air inlet feeding air into the void within the outer shell. This also shows the second air inlet feeding air into the rotating component. There is a l-2mm gap between the first air inlet and the second air inlet. This is highlighted by an arrow. Optimally this gap may be

RECTIFIED SHEET (RULE 91) ISA/EP 1.25mm. A gap between the first air inlet and the second air inlet is necessary to prevent friction, and to prevent noise from the surfaces contacting whilst the rotating component is rotating. However, the gap must not be too large as this allows air to escape and may induce turbulence and even lead to air layers disassociating from one another. It has been found that a l-2mm reduces the drag and reduction in air flow - whilst also minimising the amount of contact between the first and second air inlets during use. Indeed, it has been found that only sharp rotations of the head by the user may induce such contact at the gap of 1.25mm, whilst air turbulence is suitably reduced.

This gap may be between the closest point on the second air inlet and closest point on the first air inlet. In some embodiments this closest point may constitute an annulus on both air inlets, as the first and second air inlets may be positioned concentrically to produce an even flow of air through the rotating component.

Figure 19 shows an exploded view of the indicator. This shows the indicator spring, the outer housing, the rotor element, the rotor backing, and the base plate. The indicator spring may be in the form of a clock spring as shown.

The housing outer is sized to receive the rotor element therein. The rotor element may have a central axle aligned with the longitudinal central axis of the rotor element. The rotor backing comprises inwardly extending spokes supporting a central hub configured to receive one end of the axle. Although not shown in this Figure the outer housing may comprise a corresponding set of spokes supporting a central hub (not shown) configured to receive the opposite end of the central axle. The outer housing and the rotor backing thereby support the rotor element for rotation within the housing.

The spring is a spiral shaped spring comprising an attachment element in the shape of a U or L-shaped hook positioned at the outside terminal end of the spiral and a hub positioned at the inner terminal end of the spiral. The hook of the clock spring is connectable to the outer housing and the hub of the spring is connectable to the central axle of the rotor element. The rotor element and the outer housing are is generally hollow such that air can pass from one side of the indicator (which may be referred to as a flow rate meter) to the other. As such, the rotor element and the outer housing form part of the air flow pathway.

The rotor element comprises a number of rotors (or baffle elements) extending across the centre of the rotor element. The rotors are inclined relative to the direction of flow through the rotor element such that incident air causes the rotor element to rotate about the central axle against the action of the spring.

Figure 20 shows a plan view of the base plate of the indicator. This is a thin circular disc with two holes at the top for mating the base plate to the rotor backing.

Figure 21 shows a plan view of the spring of the indicator. This spring is configured to invert at a force that is equal to the force provided by the air flow at a predetermined level. Therefore, the spring can indicate that the air flow is not being provided at the predetermined level. If the air flow is not sufficient this can be a hazard to the user. So the use of this spring offers a safety indicator to the user. The spring comprises an L-shaped, or U-shaped attachment means. This attachment means may be used to attach the spring to a protuberance on a co-operating member of the indicator. For example, said protuberance may be on the outer housing, or any other suitable portion of the indicator to keep the spring of the indicator in place. The U or L- shaped attachment means may be particularly simple to assemble as it reduces complex or fiddly spring attachment, and so saves time in the assembly of the indicator.

Figure 22a shows a plan view of the central axle in the indicator. The axle may be attached to the rotor backing, through the rotor element (and therefore also through the outer housing within which the rotor element sits), and the other end of the axle is then connected to the spring. This axle is generally tubular, and is elongate. The axle comprises a proximal portion, a distal potion and a central portion. The central portion is covered with a resistive pattern. The central potion is the portion that may be in contact with the rotor of the indicator. Therefore, the central portion is covered in a resistive pattern to provide greater contact between the rotor and the axle.

Figure 22b shows a pattern of the central portion of the axle. This is the resistive pattern shown in Figure 22a. The resistive pattern may be any resistive pattern that is suitable. However, this example may be particularly advantageous. In this example the resistive pattern is a knurling pattern. This is formed from interlocked elongate hexagonal elements, that when locked together leave central gaps in the pattern, wherein these gaps are diamond shaped (as in the four sided shape, rather than a cut of a stone diamond). This means that the contact surface on the knurling pattern varies, and this helps to give greater grip to the axle.

Figure 23a shows a plan view of the rotor of the indicator. This shows three rotors that are housed within a cylindrical member. These rotors form the shape of a marine propeller (a type of screw propeller). The rotors comprise curved blades that sweep across an angular range of 68-78 degrees (optimally 73 degrees). This angular range is highly specific. It has been found that the force at which the spring of the indicator flips from one state (e.g. showing the device to be in a safe condition) to a second state (e.g. showing the device to be in an unsafe position) is different for going from state one to state two, than for going from state two to state one. The spring is therefore calibrated such that false negatives (where the user is erroneously informed that the device is not functioning as intended) are minimised, whilst true failures are still detected. It has been found that this calibration is enhanced by having the curved blades sweep across the above angular range.

Figure 23b shows a cross section of the rotor showing various cut through.

Figure 23c is a first cut through showing a cross section of the rotor. This is along the E-E section of Figure 23b. This shows that one rotor in cross section (of the right of the Figure) extending outwardly towards the circumference of the cylindrical member towards the base of the cylindrical member. This also shows that each rotor is thin and so forms a curved plane. A second rotor (on the left of the figure) is also shown. This rotor is shown in plan view (as the rotors are different positions so are at different views in this cross section). Therefore, this rotor appears to be a flat plane (although in practice it is curved in the same manner as the other rotor shown).

Figure 24a shows a plan view along section G-G of Figure 22b. This shows that at section G-G the three rotors all form straight lines in cross-section.

Figure 24b shows a plan view along section H-H of Figure 22b. This shows that at section H-H the cross section of the rotors is beginning the curve. It is noted that this curve is perpendicular to the curve shown in Figure 23c, and show that the rotor blades each curve in two directions. This curvature forms the marine propeller shape o screw propeller shape) of the rotor blades.

Figure 24c shows a plan view along section I-I of Figure 22b. This shows that at section I-I that rotor is at its maximum curvature.

Figure 25a shows a plan view along section J-J of Figure 22b. This shows that at section J-J the rotors are back to being relatively straight in cross section, but are displaced relative with the cross section at G-G.

Figure 25a shows the portion of the rotor that mates with the base plate. The two pins are configured to mate with the base plate. It is noted that this element is optional. This element anchors the axle of Figure 22 and positions it within the centre of the rotor element. The division into three segments may also help with air flow in some embodiments. This same division may also be present on the front of the rotor arrangement (where the spring is attached)

Figure 25b shows this same portion in perspective view.

Figure 26a shows the front of the outer casing. This end of the outer casing is suitable for attachment to the spring. This shows an air divisor (similar to that shown in Figure 25) at the front of the outer casing. This divisor may also aid with air flow. As well as the divisor also shown is a protuberance that is located adjacent one of the arms of the divisor (it is noted that the protuberance may be situated on the casing away from one of the arms but that this may increase drag and turbulence). This protuberance is used for attaching the U or L-shaped hook of the spring to such that the spring is attached to the indicator. The axle may also pass through the spring in some embodiments to keep the spring centralised.

A second protuberance is also shown - situated outside the circumference of the rotor assembly. This may help the user in assembling the collar as this protuberance may be inserted into a groove n the collar that is situated adjacent the flat portion of both the top and bottom half of the collar - such that the indicator may be positioned in either side of the collar body during assembly to aid with flexibility.

Figure 26b shows the front of the rotor for attachment to the spring in perspective view. This shows the side protuberance attached to the outer casing. This shows the extent of the protuberance in this embodiment. This gives an indication of how this may be slotted into a groove on the collar.

Figure 27a shows a perspective view of a cable end with a locking pattern to prevent inadvertent decoupling of the cable from the power source. In this case the locking pattern comprises two atraumatic nodules located either side of the cable at the point the cable attaches to the power unit. The cable can therefore be inserted into the power unit and then rotated by the user. The nodules then lock into coupling voids situated in the power unit (or a casing surrounding the power unit so the system is compatible with multiple power units). Once rotated the cable cannot be removed from the power unit without further rotation being applied to return the cable to its original position with the nodules no longer aligned with the coupling voids. This rotation therefore prevents the cable from inadvertently decoupling with the power unit during use (for example due to the cable snagging on surface whilst the user is within the respirator.

Figure 27b shows a plan view of the end of the cable with the locking pattern. This also shows the elements of the cable in cross section with the outer casing of the cable surrounding a conducting element. The end of the cable comprises an over moulded portion to which the nodules are attached/integrally formed.

It is noted that regardless of the locking pattern a voltage may preferably be provided that is within the range of 5.1v to 5.4v and that comprises direct current. This voltage range may be particularly advantageous. The only powered element in this embodiment is the impeller. Providing a voltage in this range for the impeller enables the impeller to provide sufficient air flow for various applications. In some embodiments this may be 1701 of air flow per minute. However, more power may also significantly increase the noise produced by the impeller and by the resultant air flow. Noise has been found to be a great problem for respirators, especially in clinical settings where the user of the respirator often has to communicate with others such as patients and colleagues. The lower level of noise provided by using a 5.1v to 5.4 DC voltage means that the respirator is improved whilst still providing sufficient air flow for the intended use. In particular, the voltage range 5.2 to 5.3v has been found to be extremely beneficial, and a voltage of 5.25v has been found to be optimal.

It is noted that features of each of the embodiments described above, specifically the embodiment shown as well as those optional features described in the text above may be combined with the features of the other embodiments. For example, the hood described may be combined with any suitable collar, but it may be preferably combined with the collar also described herein. The impeller described herein may be particularly well adapted for use with the collar, and in some embodiments with the hood. However, the impeller may also be used on its own in separate applications. The indicator may be particularly suited to both the collar and to the impeller, but again may be used in separate applications. Each of these elements descried are intended to be combined together to form a single respirator that is particularly advantageous as it is effective at preventing the ingress of hazards from the outside environment, and is designed to provide required air flow, and to reduce the amount of noise generated, whilst being comfortable to wear for the user. The respirator as a whole is therefore highly advantageous over those that have come before, and the components are even more beneficial when used together as a respirator as a whole than when used apart. For example, the hood shape and the air outlet of the collar are designed together to create optimal air flow within the hood that avoids facial features of the user. Either hood or collar used without the other may provide some benefits but may not be as beneficial as when used together in the respirator as described above.

Claims

28 Claims

1. A collar for a powered air purifying respirator, wherein the collar is configured to be attached to a hood element such that in use the collar and hood prohibit external fluids from entering the hood, the collar comprising: a collar body situated in a plane, wherein the collar body comprises a torus shape; a fluid inlet configured to house a filter element, the fluid inlet providing a pathway to a void configured to house an impeller; an internal fluid pathway taking air from the void; and a fluid outlet configured to outlet the air from the void; wherein the fluid outlet is angled such that air output from the fluid output emerges at an acute angle relative to the plane of the collar body.

2. The collar of claim 1, wherein the fluid outlet is angled such that air output from the fluid output emerges at an angle of between 25 degrees and a maximum of 60 degrees from the plane of the collar body, preferably wherein said angle is between 35 and 40 degrees, and more preferably wherein said angle is 38 degrees.

3. The collar of any of claims 1 or 2, wherein the fluid outlet is angled such that in use air output into the hood forms a helix within the hood and rotates around the hood adjacent to the circumference of the collar body.

4. A collar for a powered air purifying respirator, wherein the collar is configured to be attached to a hood element such that in use the collar and hood prohibit external fluids from entering the hood, the collar comprising: a collar body situated in a plane, wherein the collar body comprises a torus shape, and further wherein the collar body is formed from a bottom half and a top half; a fluid inlet configured to house a filter element, the fluid inlet providing a pathway to a void configured to house an impeller; an internal fluid pathway taking air from the void; and a fluid outlet configured to outlet the air from the void; wherein a proximal end of the internal fluid pathway connected to the void configured to house the impeller is encapsulated in the top half of the collar body.

5. The collar of claim 4, wherein the proximal end of the internal fluid pathway is directly connected to the void.

6. The collar of any of claims 4 or 5, wherein the proximal end of the internal fluid pathway is entirely within the top half of the collar body.

7. The collar of any of claims 4-6, wherein a distal end of the internal fluid pathway is housed in both the top half and bottom half of the collar body.

8. The collar of any of claims 4-7, wherein the fluid outlet is positioned on the top half of the collar body.

9. A collar for a powered air purifying respirator, wherein the collar is configured to be attached to a hood element such that in use the collar and hood prohibit external fluids from entering the hood, the collar comprising: a collar body situated in a plane, wherein the collar body comprises a torus shape; a fluid inlet configured to house a filter element, the fluid inlet providing a pathway to a void configured to house an impeller; an internal fluid pathway taking air from the void; and a fluid outlet configured to outlet the air from the void; further comprising a hole configured to house a power cable having a selected diameter, wherein the hole enables access to the void configured to house the impeller, and wherein the hole is sized to be flush with the cable diameter.

10. The collar of claim 11, wherein the hole has a diameter of 4mm.

11. The collar of claims 10 or 11, wherein between the hole and the void is a channel that forms a U-bend for the cable to pass through.

12. A collar for a powered air purifying respirator, wherein the collar is configured to be attached to a hood element such that in use the collar and hood prohibit external fluids from entering the hood, the collar comprising: a collar body situated in a plane, wherein the collar body comprises a torus shape, and further wherein the collar body is formed from a bottom half and a top half; a fluid inlet configured to house a filter element, the fluid inlet providing a pathway to a void configured to house an impeller; an internal fluid pathway taking air from the void; and a fluid outlet configured to outlet the air from the void; wherein the bottom half and the top half of the collar body are joined by a double sided adhesive gasket.

13. The collar of claim 12, wherein the double sided adhesive gasket is formed from 3M tape.

14. The collar of claim 12 or 13, wherein the gasket is coated in an adhesive on both sides.

15. The collar of claim 14, wherein the adhesive is acrylate.

16. The collar of claims 14 or 15, wherein the adhesive layer is 0.05mm to 0.1mm thick, preferably wherein the adhesive is 0.076mm thick.

17. A collar for a powered air purifying respirator, wherein the collar is configured to be attached to a hood element such that in use the collar and hood prohibit external fluids from entering the hood, the collar comprising: a collar body situated in a plane, wherein the collar body comprises a torus shape, and further wherein the collar body is formed from a bottom half and a top half; a fluid inlet configured to house a filter element, the fluid inlet providing a pathway to a void configured to house an impeller; an internal fluid pathway taking air from the void; and a fluid outlet configured to outlet the air from the void; the collar body further comprising an indent configured to house an indicator, wherein the indent comprises a groove to mate with an alignment portion on the indicator, wherein the groove is positioned adjacent the join of the top half and bottom half of the collar body.

18. The collar of 17, further comprising a collar perpendicular to the groove to align a first edge of the indicator with.

19. The collar of claim 18, further comprising a second collar perpendicular to the groove and parallel with the first collar to align a second edge of the indicator with.

20. The collar of claim 19, wherein the indicator is substantially cylindrical and the first and second edges refer to the top and bottom flat surfaces of the cylinder.

21. The collar of any preceding claims, wherein the torus of the collar body has a diameter of 32mm.

22. The collar of any preceding claim, wherein the collar comprises an impeller housed in the void, the impeller configured to provide air flow to the air outlet.

23. The collar of claim 22, wherein the impeller draws air in from the air inlet.

24. The collar of any of claims 22 or 23, wherein the impeller is powered by a 5.1v- 5.4v voltage source.

25. The collar of any of claims 22-24, wherein the collar comprises a filter positioned in the air inlet and positioned on the opposite side of the air inlet than the impeller.

26. The collar of any preceding claim, wherein the collar comprises an indicator to indicate that the air flow out of the impeller is above a predetermined level.

27. The collar of claim 26, wherein the indicator is the indicator of any of claims 28- 32.

28. An indicator for use with a powered air purifying respirator, the respirator comprising a collar element, and a hood element, wherein the indicator is configured to sit in the collar and monitor the air flow through the collar, and to indicate if the air flow drops below a predetermined level, the indicator comprising: a housing; a rotor blade configured to be driven by air flow, the rotor blade situated within the housing; a spring configured to invert upon exposure to air flow over a predetermined level; wherein the spring is situated within the housing, and is attached to the housing by a hook at the end of the spring connecting to an outdent of the housing.

29. The indicator of claim 28, wherein the hook forms an L-shape around/through the outdent of the housing.

30. An indicator for use with a powered air purifying respirator, the respirator comprising a collar element, and a hood element, wherein the indicator is configured to sit in the collar and monitor the air flow through the collar, and to indicate if the air flow drops below a predetermined level, the indicator comprising: a housing; a rotor blade configured to be driven by air flow, the rotor blade situated within the housing; a spring configured to invert upon exposure to air flow over a predetermined level; wherein the rotor blade is within an inner housing, and further wherein the rotor blade extends the full length of the inner housing whilst rotating 68-78 degrees and preferably 73 degrees.

31. An air purifying respirator comprising the collar of any preceding claim, and a hood, wherein the hood and the collar are configured to be attached. 32

32. The respirator of claim 31, wherein the hood comprises a first aperture for the user's head to pass through.

33. The respirator of claim 32, wherein the hood comprises a second aperture positioned adjacent the air inlet of the filter.