This disclosure relates to a back plate for a breathing apparatus, comprising a strap which is configured so as to retain cylinders of different dimensions.

Self-contained breathing apparatus (SCBA) harnesses typically comprise a back plate for supporting a cylinder of breathable gas and a pair of shoulder straps to attach the SCBA to a user. In use, a cylinder of breathable gas is retained by a strap which is passed around an upper portion of the cylinder, tightened, and fixed in position.

Some known arrangements may suffer from tampering or loosening issues. Some known arrangements may have to be manually adjusted every time a new cylinder is installed onto the back plate, even if the replacement cylinder has the same dimensions as the previous cylinder.

It should be understood therefore that it is desirable to provide an improved arrangement for retaining cylinders on breathing apparatus.

According to a first aspect, there is provided a back plate for a breathing apparatus, the back plate having a cylinder-support side configured to support a breathing gas cylinder, and a user-facing side configured to face the user’s body in use; the back plate comprising a strap for retaining a cylinder against the cylinder-support side; and a first end of the strap being configured for connection to the back plate in a plurality of attachment positions so as to retain cylinders of different dimensions the plurality of attachment positions being arranged on the user-facing side of the back plate. The back plate may be configured to support one or more cylinders at any one time. Retaining cylinders of different dimensions may comprise retaining a cylinder with a larger dimension or a cylinder with a smaller dimension. Retaining cylinders of different dimensions may be achieved by adjusting a length or useable length of the strap. The dimension of the cylinder or cylinders may be a volume, a circumference, or a diameter. The cylinder-support side and the user-facing side may be opposite sides of the back plate. The strap may be configured to substantially surround a circumference of the cylinder, in use. As the end of the strap is located, in use, between the user’s back and the back plate, this may inhibit accidental releasing of, or tampering with, the strap. Additionally, as the end of the strap is fixed in position, in use, this may prevent the user snagging of the strap on their surroundings. The strap may have a second end.

The end of the strap may comprise a locking element. The back plate may comprise at least one anchor element. The anchor element may define one or more of the attachment positions. The at least one anchor element may be configured for engagement with the locking element to secure the strap to the back plate. The locking element and the anchor element may be moveable relative to one another between an unlocked position, in which the locking element is releasable from the anchor element, and a locked position, in which the locking element is locked to the anchor element.

The plurality of attachment positions may comprise a plurality of discrete anchor elements. The plurality of attachment positions may comprise a series of anchor elements in a row, spaced at intervals from each other. This may provide a discrete adjustment scale.

The at least one anchor element may be movable to different positions to provide the plurality of attachment positions. The at least one anchor element may be adjustable, such as by being slidable on a rail, so as to be located and fixed at different positions by the user. This may provide a continuous, rather than a discrete, adjustment scale.

The locking element and the strap anchor may be rotatable relative to each other in order to move between the unlocked position and the locked position.

The back plate may comprise a cradle which may extend through the back plate so as to provide a cylinder support element on the cylinder-support side and provide the plurality of attachment positions on the user-facing side. The cradle may provide the anchor elements.

The connection of the first end of the strap to the back plate in a plurality of attachment positions may provide adjustment of a working, or useable, length of the strap so as to retain cylinders of different dimensions.

The strap, in use, may define a cylinder-retaining loop which extends around the cylinder between a first contact point of the strap with the back plate and a second contact point of the strap with the back plate. Connecting the strap at the different attachment points may adjust the length of the cylinder-retaining loop. The cylinder-retaining loop may define the working length of the strap.

The attachment positions may be arranged transversely on the user-facing side of the back plate. The attachment positions may be arranged such that, in use, they are arranged horizontally. The attachment positions may be arranged to be parallel to the direction of the strap around the cylinder. The attachment positions are arranged longitudinally on the user-facing side of the back plate. The attachment positions may be arranged such that, in use, they are arranged vertically. The attachment positions may be arranged to be perpendicular to the direction of the strap around the cylinder.

The strap may comprise a second end at an end opposite to the first end. The second end may be fixed in an adjustable manner, such as like the first end. The second end may be fixed in a permanent manner. The second end may be attached to the back plate. The second end may be attached to the cylinder support side of the back plate. The second end may alternatively be attached to the user-facing side of the back plate

The strap may comprise a tensioning device for applying tension to the strap, in particular, along the length of the strap. The tensioning device may be a tensioning buckle operable between an open position, and a closed position in which tension is applied along the length of the strap so as to retain the cylinder. The tensioning device may reduce a working length of the strap.

The one or more anchor element may comprise a slot, and the locking element may comprise a projection configured for insertion into the slot. The projection may be inserted into the slot in a direction substantially perpendicular to the back plate. After insertion into the slot, the projection may be rotated so as to be retained within the slot. The rotation may be 90 degrees.

According to a second aspect, there is provided a cradle for use with a back plate according to any statement herein. According to a third aspect, there is provided a breathing apparatus comprising a back plate according to any the first aspect described above.

The skilled person will appreciate that except where mutually exclusive, a feature described in relation to any one of the above aspects may be applied mutatis mutandis to any other aspect. Furthermore except where mutually exclusive any feature described herein may be applied to any aspect and/or combined with any other feature described herein.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 schematically shows a back plate for supporting a cylinder of breathable gas;

Figure 2 schematically shows a view of the back plate of Figure 1 taken along line AA, with a cylinder of breathable gas attached;

Figure 3 schematically shows a cradle configured to be attached to the back plate with a locking element attached to an anchor element in an unlocked position;

Figure 4 schematically shows the back plate with the locking element attached to the anchor element in a locked position;

Figure 5a schematically shows the cradle, and an attachment member for attachment to the cradle; Figure 5b schematically shows another embodiment of an attachment member for attachment to the cradle;

Figure 6 schematically shows the cradle with two cylinders of breathable gas attached;

Figure 7 schematically shows an alternative embodiment of the present invention in which the anchor element is movable along the cradle; and

Figures 8a and 8b schematically show an alternative embodiment of the present invention in which the anchor elements are arranged on the back plate in a longitudinal direction.

Referring to Figure 1 , a breathing apparatus 10 comprising a back plate 100 is schematically shown. In the view of Figure 1 , a user-facing side 122 of a back plate 100 is shown, the back plate 100 comprising a substantially rectangular back region 102, a cradle 104, and shoulder straps 106. In use, the back plate 100 is configured to overlie at least a portion of a user’s back. The back plate 100 has a user-facing side 122 to be arranged in contact against or to face a user’s back in use, and an opposing cylinder- support side 124 (not visible in Figure 1) on which a cylinder 108 is located in use. The cradle 104 is arranged to support a breathing gas cylinder 108 on the cylinder-support side 124 of the back plate 100. The shoulder straps 106 are provided for attaching the back plate 100 to a user. The back plate 100 may also comprise a waist belt for securing the back plate 100 at a user’s waist.

With reference to Figure 2, the breathing apparatus 10 is shown in cross section on the plane A shown in Figure 1. In this figure, it can be seen more clearly that the back plate 100 comprises a user-facing side 122 and a cylinder-support side 124. The cradle 104 extends through the back plate 100, at an upper portion of the back plate 100. A strap 1 10 is provided so as to retain a breathing gas cylinder 108. The strap 1 10 has a first end 1 14 and a second end 112. The first end 1 14 is arranged to be attached to a user facing side of the cradle 104. The strap 1 10 passes around the cylinder 108 and the second end 1 12 is fixedly attached to the cradle 104 at a cylinder-support side.

Referring to Figures 3, 5a and 5b, the cradle 104 is shown in greater detail. The cradle 104 comprises a cylinder-support element 126 on the cylinder-support side. The cylinder support element 126 is arranged to support breathing gas cylinders of various sizes. The cylinder support element can support a single cylinder or can support multiple cylinders (as shown in Figure 7).

The user-facing side of the cradle 104 comprises a row of anchor elements 1 18 arranged transversely across the cradle 104. The anchor elements 118 define a plurality of attachment positions for the first end 114 of the strap 1 10 to be attached to the cradle 104, and therefore the back plate 100. Each anchor element 1 18 is separated by a panel 144. The cradle 104 comprises a flange 140 on an upper and lower end. The flange 140 comprises a plurality of holes 142 for attachment of the cradle 104 to the back plate 100. Although in this embodiment, a cradle 104 is provided for fitting to the back plate 100, the cradle 104 comprising the anchor elements 1 18, the skilled person would understand that in other embodiments the anchor elements 1 18 may be moulded or otherwise formed directly on the back plate 100.

Each anchor element 1 18 defines an entry region 152 and a retaining region 154. The entry region 152 is substantially rectangular in cross-section with a width D1. The retaining region 154 is substantially circular in cross-section and has a diameter D2, which is larger than the width D1. The strap 110 is formed of a flexible/woven material and extends along a length between the first end 114 and the second end 112 of the strap 110. The first end 114 of the strap 110 comprises an attachment member 131 , which comprises a locking element 116 configured to be inserted into any one of the plurality of anchor elements 118.

As shown in Figure 5a, the attachment member 131 has a planar base 138, comprising a body region 133 and an arm region 134 which defines a T-shape. The arm region 134 defines the locking element 116. The cross section of the locking element 116 is defined by two shorter opposing arcuate surfaces 135a separated by two substantially planar surfaces 135b disposed at opposite sides of the arm region 134. The locking element 116 has a length D3 and a width D4. The length D3 is larger than the width D4. The length D3 is slightly smaller than the diameter D2 of the retaining region 154. The width D4 of the locking element 116 is slightly smaller than the width D1 of the retaining region 154. The locking element 116 is configured for engagement with the anchor element

118 to secure the strap 110 to the back plate 100.

The locking element 116 can be inserted into an anchor element 118, in a first (or unlocked) position, in which the locking element 116 is orientated such that the arm region 134 can be inserted through the entry region 152 into the retaining region 154 (as the dimension D4 is smaller than the dimension D1). The attachment member 131 can then be rotated to a second (or locked) position by pivoting the attachment member 131 about the centre of the retaining region 154. After a rotation of 90 degrees, as shown in Figure 4, the locking element 116 is prohibited from removal through the entry region 152 as the dimension D3 is larger than the dimension D1. As a result, the locking element 116 is locked to the anchor element 118. As seen in Figure 5a, in this embodiment, the attachment member 131 is formed by two wall regions 132 protruding from opposing ends of the body region 133, each wall region 132 forming a right-angled triangle, with a rounded corner 135 at the corner of the triangle opposite to the body region 133. Each wall region 132 comprises a hole 136 proximate to the rounded corner 135. The first end 114 of the strap 1 10 is attached to the attachment member 131 through the holes 136. The skilled person will appreciate that other configurations of the attachment member may be provided, such as the attachment member 231 of Figure 5b. In this arrangement, the attachment member 231 has a body region 233 which is planar, and substantially H shaped. A locking element 216 is formed by arm regions 234 which project laterally from each upper end of the body region 233. The arm regions 234 have the same shape and size of cross-section as the locking element 1 16 defined by the arm regions 134 as discussed above, and as shown in Figure 5. The first end 114 of the strap 1 10 may be wrapped around a central bar 235 of the H portion and stitched to itself, so as to fix the strap 1 10 to the attachment member 231.

Referring back to Figures 3 and 4, the strap 110 passes from the first end 114 which is attached to the anchor element 118, around the breathing gas cylinder 108. The second end 1 12 of the strap 110 is fixedly attached to the cylinder-support side of the cradle 104 by means of a tensioning buckle 120. The tensioning buckle 120 is movable between an open position (Figure 3) and a closed position (Figure 4). In the closed position, the tensioning buckle 120 applies tension along the length of the strap 1 10. In the closed position, the breathing cylinder 108 is firmly held in place by the strap 1 10 and is thus fixed to the cradle 104 (and the back plate 100).

The strap 1 10 passes around the cylinder 108 and is in contact with the cylinder-support side of the cradle 104 at a first contact position 128 and a second contact position 130. A cylinder-retaining loop of the strap 1 10 is defined between the first and second contact position 128, 130. The length of the strap 110 between the two contact positions 128, 130 defines a working length L of the strap 110.

By selecting the position of the attachment member 131 in one of the plurality of anchor elements 118, the working length of the strap 110 can be adjusted. In this way, the back plate 100 of the present invention can be used to retain at least one breathing gas cylinder 108 of a range of diameters and volumes.

In use, in order to retain a cylinder on the back plate 100, a breathing gas cylinder 108 (or a plurality of breathing gas cylinders 208) is placed on the cylinder support element 126 on the cradle 104. The tensioning buckle 120 is in the open position, and the strap 110 is passed around the cylinder 108 or cylinders 208. The locking element 116 on the first end 114 of the strap 110 is inserted, in an unlocked position, into an appropriate anchor element 118, so as to adjust the working length L such that the strap 110 is taut. The attachment member 131 is pivoted 90 degrees about the centre of the retaining region 154, in the direction in which the strap 110 extends from the attachment member 131 , so as to move the locking element to the locked position. This rotation rotates the locking element 116 by 90 degrees, and thus prevents removal of the locking element 116 from the anchor element 118 through the entry region 152. The rotation additionally causes a small amount of slack to be introduced into the strap 110. The tensioning buckle 120 is moved from the open position to the closed position, thereby applying tension along the length of the strap 110, and firmly fixing the cylinder 108, to the cradle 104 and the back plate 100.

Figure 6 shows the back plate 100 with two breathing gas cylinders 208 retained by the strap 110. The back plate 100 additionally comprises a central connector 202 arranged between the cylinders 208, through which the strap 110 passes. The central connector 202 increases the surface area of contact of the strap 1 10 with the cylinders 208, thereby increasing the force with which the cylinders 208 are retained. In some arrangements a kit including a set of straps 100 of different lengths may be provided, in order to provide for a larger range of cylinder sizes.

Figures 7, 8a and 8b show alternative embodiments of the invention. Figure 7 shows an adjustable anchor element 150 positioned on a rail 148. An attachment member 131 is provided on the first end of the strap 1 10, which comprises a locking member 1 16. The interaction of the locking member 116 and the anchor member 150 is as described above. In this embodiment, the plurality of attachment positions, and therefore the adjustment of the working length L of the strap is provided by the adjustment of the anchor member 150 along the rail 148. The anchor member 150 can be adjusted to a continuous range of positions along the rail 148, and fixed in the desired position, before insertion of the locking member 1 16 into the anchor member 150 and rotation of the attachment member 131 from the unlocked position to the locked position, thereby locking the locking member 1 16 to the anchor member 150. In another example, movement of the locking member 1 16 to locked position may lock the anchor member 150 in position on the rail 148, for example by a cam mechanism or similar.

In Figures 8a and 8b, the plurality of attachment positions is provided longitudinally along the length of the back plate 200. In this embodiment, a column of anchor elements 218 are provided on the back plate 200, providing discrete positions at which a locking element may be located. However, it will be appreciated by the skilled person that an adjustable anchor element positioned on a rail may also be used, such as discussed above in relation to Figure 7. In this embodiment, the attachment member 231 of Figure 5a is shown, however it will be appreciated that alternative attachment members, such as the attachment member 131 shown in Figures 2-5a. In this embodiment, a turning element 252 is provided, which changes the direction of the strap 110 by 90 degrees and thus enables attachment of the strap to one of the column of anchor elements 218. Providing the anchor elements 218 along a longitudinal direction of the back plate 200 may enable a greater range of attachment positions, and therefore a greater range of adjustment of the working length L of the strap 110, than a transversely arranged row of anchor elements as the back plate 200 is typically longer in the longitudinal direction than the transverse direction.

Although throughout the detailed description, the locking member has been described as an arm portion which acts as a protrusion to be inserted into a slot defined by the retaining portion of one of the plurality of anchor members attached to the back plate, it will be appreciated by the skilled person that the arrangement could be reversed, such that the anchor member could comprise a protrusion which can be received within a slot defined by a retaining portion of the locking member.

It will be understood that the invention is not limited to the embodiments above-described and various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and sub-combinations of one or more features described herein. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word“comprising” does not exclude other elements or steps, and the indefinite article“a” or“an” does not exclude a plurality. Any reference signs in the claims should not be construed as limiting the scope.