High pressure air cylinders for use with self-contained breathing apparatus

ES 2 706 450 T3

DESCRIPTION

High pressure air cylinders used with self contained breathing apparatus

Field of the invention

The present invention relates generally to a self-contained breathing apparatus and more particularly to a self-contained breathing apparatus having an improved air cylinder configuration that is lighter and smaller than conventional air cylinders, by while providing the desired air capacity and compatibility with existing infrastructure.

Background of the invention

A Self Contained Breathing Apparatus (SCBA) used by a firefighter generally includes a cylinder of pressurized air to supply breathing air, a pressure regulator, an inhalation connection (mouthpiece, mouth mask or face mask) and other devices mounted on a frame that is worn by the firefighter. The configuration of the air cylinder is usually the result of consideration of several design factors. These include such items as size, weight, amount of air supply required, portability, compatibility with other standardized equipment, and the like. Current air cylinders for firefighters are pressurized to approximately 15 MPa (2,216 pounds per square inch (psi)) or 31 MPa (4,500 psi).

In use, it is desirable to provide an SCBA with sufficient air capacity so that the user is not limited in his work by having to leave the site to obtain replacement air cylinders. However, the increased air capacity must be balanced with the need for a manageable SCBA both in terms of weight and space. In this regard, various air cylinder configurations have been used to provide a desired air capacity. In one configuration, two standard size air cylinders have been used to provide a desired air capacity. In another configuration, multiple air cylinders are used, a reduced profile is used to provide greater maneuverability, while maintaining the desired capacity. Since these configurations require the use of more than one cylinder, however, they can undesirably result in increased weight. They can also be difficult to handle and may require the use of specialized equipment and retraining of fire department personnel to ensure proper operation.

In still other configurations, the air cylinders are made of specialized materials, such as carbon fiber composite material, to provide a cylinder pressure of 66 MPa (9,500 psi) or more. Such configurations, while providing a desirable increase in air capacity, also result in higher manufacturing costs. Such configurations can also result in increased weight.

Therefore, it would be desirable to provide an improved air cylinder that has a full envelope that takes up less space while maintaining existing air capacity. The resulting cylinder must be easy to use, inexpensive to manufacture, and must meet the current cylinder loading infrastructure.

WO2008 / 061021, which is considered to represent the closest prior art, discloses that the weight and capacity of an SCBA reservoir can be varied by adjusting the pressure and physical dimensions of the reservoir.

Compendium of the invention

According to the present invention, there is provided a self-contained breathing apparatus according to claim 1.

More particularly, a self-contained breathing apparatus is disclosed. The self-contained breathing apparatus includes an air cylinder capable of being pressurized from approximately 37 MPa (5,400 psi) to approximately 41 MPa (6,000 psig). In an exemplary embodiment, the air cylinder is capable of being pressurized to approximately 38 MPa (5,500 psig). In another exemplary embodiment, the air cylinder is capable of being pressurized from about 37 MPa (5,400 psig) to 39 MPa (5,600 psig). The air cylinder is optimized for size and weight, and is compatible with the infrastructure used in conjunction with conventional air cylinders. The self-contained breathing apparatus also includes a first regulating valve, to reduce the pressure of the air received from the air cylinder to a predetermined level. A second regulating valve is arranged to reduce the pressure of the air received from the first regulating valve to a level suitable for use by a user. Air supplied from the second regulating valve is provided to the user through a mask. The self-contained breathing apparatus further includes a frame to support the air cylinder at the back of the user.

A compressed gas cylinder is described. The cylinder may comprise a pressurized volume portion to contain a volume of gas pressurized at a service pressure . The volume portion under pressure may have a length, a diameter, and a volume of water selected according to the formula:

ES 2 706 450 T3

7πά² πά ~ where: L = length, V = volume of water and d = diameter. The service pressure can be from approximately 34 MPa (5,000 pslg) to approximately 41 MPa (6,000 pslg). The service pressure can also be from about 37 MPa (5,400 pslg) to about 39 MPa (5,600 pslg). The cylinder may further include a gas transmission valve for coupling to a pressure regulating assembly.

Also, a self-contained breathing apparatus is described. The self-contained breathing apparatus may include a compressed gas cylinder comprising a pressurized volume portion to contain a volume of gas pressurized to an operating pressure. The volume portion under pressure can have a length, diameter, and water volume selected according to the formula:

-XD² ~ ^ + d where: L = length, V = volume of water and d = diameter. The service pressure can be from approximately 34 MPa (5,000 pslg) to approximately 41 MPa (6,000 pslg). Alternatively, the service pressure can be from about 37 MPa (5,400 pslg) to about 39 MPa (5,600 pslg). The cylinder may also include a gas transmission hole. The self-contained breathing apparatus may also include a first regulating valve coupled to the gas transmission port to receive compressed gas from the pressurized volume portion. The first regulating valve can be configured to reduce the pressure of the received gas from the volume portion under pressure to a second pressure that is less than the first pressure. A second regulating valve may be arranged in fluid communication with the first regulating valve to receive compressed gas from the first regulating valve. The second regulating valve may be configured to reduce the pressure of the gas received from the first regulating valve to a third pressure that is lower than the second pressure. Also, a mask portion may be provided. The mask portion may be in fluid communication with the second regulating valve, to provide gas at the third pressure to a user. The self-contained breathing apparatus may further include a frame portion having a user support portion to allow a user to carry the compressed gas cylinder.

Brief description of the drawings

By way of example, a specific embodiment of the described device will be described below, with reference to the attached drawings, in which:

Figures 1A to 1D represent the first, second, third and fourth embodiments of the disclosed air cylinder;

FIG. 2 is a cross-sectional view of an exemplary embodiment of the disclosed air cylinder and a conventional air cylinder positioned relative to the center of gravity of a user;

Figure 3 is an exemplary comparative table of length, diameter, weight, and mass dimension values ​​for disclosed air cylinders compared to conventional 31 MPa (4,500 psi) air cylinders used to calculate the values ​​of the Inertia of relative rotation with respect to a typical user;

Figure 4 is a schematic comparing the external dimensions of an exemplary embodiment of the disclosed air cylinder and a conventional 31 MPa (4,500 pslg) air cylinder;

Figure 5 is a graph of pressure versus cylinder Internal volume for an exemplary realization of the disclosed air cylinder;

FIG. 6 is a second graph of pressure versus cylinder Internal volume for an exemplary realization of the disclosed air cylinder;

Figure 7 is a graph of the first derivative of pressure versus cylinder Internal volume for an exemplary realization of the disclosed air cylinder;

FIG. 8 is a graph of cylinder length versus cylinder diameter for an exemplary embodiment of the disclosed air cylinder;

Figure 9 is a three-dimensional plot of cylinder length versus cylinder diameter and cylinder weight for an exemplary embodiment of the disclosed air cylinder;

Figure 10 is an exemplary comparative table of length, diameter, and weight dimension values ​​for an exemplary embodiment of the disclosed air cylinder compared to a conventional 31 MPa (4,500 psi), Figure 11 is a comparison of various exemplary embodiments of the disclosed air cylinder compared to corresponding conventional 31 MPa (4,500 psig) air cylinders;

Figure 12 is a schematic of a self-contained breathing apparatus for use with the air cylinders disclosed in Figures 1A through 1D.

Detailed description

It should be understood that the disclosed apparatus is not limited in its application to the details of the construction and arrangement of the components set forth in the following description or illustrated in the following drawings. The disclosed apparatus is capable of other embodiments and can be practiced or carried out in various ways. Furthermore, it should be understood that the phraseology and terminology used herein is for descriptive purposes and should not be construed as limiting. The use of including, comprising, or having and its variations herein is intended to encompass the items listed below and their equivalents, as well as additional items. Unless otherwise specified or limited, the terms mounted, attached, supported, and attached and their variations are widely used and include direct and indirect mounts, connections, brackets, and couplings. Furthermore, connected and coupled are not limited to physical or mechanical connections or couplings. In the following description, like reference numbers and labels are used to describe like, similar or corresponding parts in the different views of the figures.

Referring now to Figures 1A to 1D, a plurality of air cylinders 10, 12, 14, 16 are shown in accordance with the invention. Cylinders 10-16 are configured for use in a self-contained breathing apparatus (SCBA) used by firefighters, first responders, members of hazardous materials response teams, rescuers, and the like. Although the description will continue in relation to the use of the disclosed apparatus by firefighters, it will be appreciated that the disclosed cylinders are equally applicable to other uses.

As will be described in greater detail below, the air cylinders 10-16 are configured to have a smaller total space envelope compared to traditional cylinders, while still maintaining the desired standard breathing air volumes. As shown, each of the cylinders 10-16 has a pressurized volume portion having a length L and a diameter d which, together, define the total space envelope of each cylinder. Traditional SCBA cylinders are configured to provide breathing air capabilities in a variety of time increments (eg, 30 minutes, 45 minutes, 60 minutes, and 75 minutes). It will be appreciated that these durations are based on a nominal air consumption rate of 40 liters per minute. To obtain sufficient free air volumes to provide breathable air in accordance with these time increments, conventional SCBA cylinders are pressurized to approximately 31 MPa (4,500 psig). This pressurization scheme results in conventional cylinders having a particular length and diameter (depending on the incremental free air capacity selected), resulting in a conventional total space envelope and weight. The disclosed air cylinders 10-16 provide the same incremental air capacities (30 minutes, 45 minutes, 60 minutes, and 75 minutes, respectively) as conventional cylinders. However, the disclosed cylinders have a lower spatial envelope (eg length and / or diameter) and / or weight compared to conventional cylinders. As will be appreciated, this less space and / or weight of the SCBA results in an SCBA that is easier to maneuver and is less likely to become entangled with the structures and contents of a building, as is often the case in confined spaces related to fire fighting operations. Furthermore, SCBAs incorporating the disclosed cylinders will be lighter than conventional air cylinders, which have corresponding free air volumes, thereby improving mobility and reducing the weight load on the firefighter. Additionally, by providing smaller diameter air cylinders, the SCBA's center of gravity resides closer to the firefighter's back, reducing operational stress. For example, Figure 2 shows a comparison of the effect of rotational inertia of the SCBA due to the location of the disclosed air cylinder 12 and the conventional cylinder 45A, relative to a user 100 (and, more particularly, their location with respect to the CG user's center of gravity). Torsional loads on an unaligned spine are greatest when a user is attempting to stop waist / chest rotation at the end of their rotational range of motion. An axial torque (τ) is necessary from above to stop the rotation, and it exerts a load on a torsional / non-aligned spine, since the muscle contraction is usually at an angle to the axis of rotation. The axial torque, τ can be represented by the following formula:

ES 2 706 450 T3 in which:

ω₂ = Final angular velocity, ωι = Initial angular velocity,

At = time period of action,

I = Rotational inertia, where

I = m (n + r₂)² in which:

m = mass, η = distance between the edge of the air cylinder and the human center of gravity, and r₂ = radius of the air cylinder, where r₂ - dcylinder / 2 and

dciiindro = diameter of air cylinder

Figure 3 is a table showing the comparative values ​​of cylinder water volume, cylinder weight, cylinder mass, air mass, r1 and r2 used to determine the rotational inertia I for cylinders 10, 12, 14 disclosed, as well as those for the respective conventional 31 MPa (4,500 pslg) cylinders of the same volumes of free air. The comparison assumes that r1 (the distance between the user's CG and the edge of the cylinder) is 10.16 cm (4 inches). As can be seen, the inertia of rotation of the disclosed cylinders 10, 12 and 14 is less than the inertia of rotation of the respective conventional cylinders having the same volumes of free air. Specifically, for the 30 minute cylinders 10 disclosed there is a 16.4% reduction in rotational inertia, for the 45 minute cylinder 12 there is an 11.1% reduction in rotational inertia, and for the Cylinder 14 of 60 minutes results in a 12.6% reduction in rotational inertia

Therefore, the disclosed cylinders reduce the effects of rotational inertia while maintaining a desired free air capacity. As can be seen, reducing the effect of SCBA Rotational Inertia reduces the chances of early fatigue and possible injury. In addition, by allowing the user to consume less energy to carry and maneuver the SCBA, the user can consume less air and consequently increase their time spent at the emergency location.

In some embodiments, priority may be given to reducing the diameter d of the cylinder as much as practical, while maintaining the desired air capacity, in order to lower the center of gravity of the SCBA and increase maneuverability. Other embodiments may be focused on reducing the length L or weight W of the cylinder, while other embodiments may provide a combination of smaller dimensions L, d, and weight W.

To obtain these less space and / or weight, the disclosed cylinders are configured to have a service pressure of from 34 MPa (5,000 pslg) to approximately 41 MPa (6,000 pslg). In some embodiments, the disclosed cylinders have a service pressure of from 37 MPa (5,400 pslg) to about 39 MPa (5,600 pslg). In other embodiments, the disclosed cylinders have a service pressure of from 34 MPa (5,000 pslg) to 39 MPa (5,600 pslg). In still other embodiments, the disclosed cylinders have a service pressure of from 39 MPa (5,600 pslg) to 41 MPa (6,000 pslg). In a particularly preferred embodiment, the disclosed cylinders have a working pressure from 38 MPa (5,500 pslg).

For the purposes of this invention, the term service pressure is as specified in 49 CFR § 173.115, entitled Shlppers - General Requlrements for Shlpments and Packaglngs, the entirety of which is incorporated herein by reference. Therefore, the term "service pressure" shall mean the authorized pressure mark on the container in which the cylinder can be loaded. For example, for a cylinder marked DOT 3A1800, the operating pressure is 12,410 kPa (1,800 pslg).

As one of ordinary skill in the art will appreciate, during cylinder loading operations, the operating pressure of a particular cylinder may be exceeded by a small amount (eg, 10%). 5

ES 2 706 450 T3

This slight overload can be useful to compensate for the heating generated when the air is compressed in the cylinder. After charging, when the air in the charged cylinder returns to room temperature, the pressure in the cylinder drops slightly. Therefore, to account for this pressure drop, the cylinder can be charged to a pressure slightly higher than the operating pressure, such that, when the temperature of the air in the cylinder returns to room temperature, the cylinder remains charged at or very close to operating pressure. Therefore, in one example, a cylinder having a working pressure of 12 MPa (1,800 psig) can be charged to a pressure of approximately 14 MPa (1,980 psig). For cylinders 10 to 16 disclosed, embodiments having a 38 MPa (5,500 psig) operating pressure would be loaded to approximately 42 MPa (6,050 psig), to ensure that cylinders 10 to 16 return to an internal pressure of approximately 38 MPa (5,500 psig) when the air temperature in the cylinders returns to room temperature. The disclosed design also allows cylinders 10-16 to be compatible with existing charging infrastructure (i.e. compressors) which are generally capable of loading up to approximately 41 MPa (6,000 psig). .

Such infrastructure compatibility also includes the size, weight, and structural limitations that currently exist for the conventional 31 MPa (4,500 psig) air cylinder deck. Therefore, the disclosed air cylinders 10 to 16 are compatible with existing air filling stations that use a reservoir or fragmentation device to protect against cylinder breakage. The conventional infrastructure platform is expected to be used to support the disclosed air cylinders 10-16.

Additionally, fire trucks typically include flip-up seats in which an SCBA, including an air cylinder, is secured by retaining clips on a seat to facilitate donning of the SCBA by a firefighter. The disclosed air cylinders 10 to 16 may be compatible with the existing infrastructure for such folding seats. The disclosed cylinders 10-16 are also compatible with existing rear frames used by firefighters to transport the SCBA. Furthermore, the disclosed cylinders are compatible with existing storage tubes used in fire stations and in fire trucks used to store air cylinders.

Referring to Figure 4, an exemplary qualitative comparison is shown between the disclosed cylinder 12 (having a 45 minute capacity, or 1,800 liter free air volume) and two traditional 45 minute cylinders. minutes 45A and 45B. As can be seen, the disclosed cylinder 12 has a smaller overall space envelope compared to traditional cylinders 45A, 45B. Compared to the traditional cylinder 45A, the disclosed cylinder 12 has a slightly longer length L, but the diameter d is substantially smaller. Therefore, cylinder 12 will not protrude as much from the user's back during operation as compared to traditional cylinder 45A (see FIG. 2). Compared to the traditional cylinder 45B, the disclosed cylinder 12 has a substantially shorter length L, while still maintaining a similar diameter d. Therefore, cylinder 12 will not protrude above the user's back during operation compared to traditional cylinder 45B. Due to these smaller dimensions, the disclosed 45-minute cylinder 12 is also substantially lighter than traditional 45-minute cylinders 45A, 45B. Similarly, similar advantages are obtained with disclosed cylinders 10, 14, and 16 compared to their conventional 4,500 psig (31 MPa) counterparts.

Therefore, the inventors have found that the disclosed cylinders 10-16 provide an optimal combination of size, weight, and air capacity for use in an SCBA, while still being compatible with existing equipment infrastructure used in conjunction with the air cylinders. The diameter, length and / or weight of the disclosed cylinders 10-16 are less than conventional air cylinders having corresponding 30, 45, 60 and 75 minute air capacities. As noted above, this reduction in size is achieved by pressurizing cylinders 10 through 16 that are disclosed to 34 MPa to 41 MPa (5,000 psig to 6,000 psig), and, in an exemplary embodiment, approximately 38 5,500 psig (MPa), resulting in smaller size and weight relative to conventional air cylinders that are pressurized to 4,500 psig (31 MPa).

It is noted that, although it is possible to design air cylinders capable of being pressurized to pressures much greater than the 34 MPa to 41 MPa (5,000 to 6,000 psig) of the disclosed cylinders, the resulting cylinders would include undesirable increases in pressure. total cylinder weight (due to substantially greater wall thicknesses) without a proportionally advantageous increase in capacity or decrease in size. Therefore, 38 MPa (5,500 psig) have been found to provide an optimal combination of size, weight, and additional air capacity for an air cylinder for use in a fire fighting environment, while maintaining compatibility with the existing charging infrastructure. This can be seen in relation to Figure 5, which is a graph of internal pressure versus internal volume of the cylinder. This example graph shows a curve for a 45 minute cylinder (ie 1,800 liters of free air). As you can see, a traditional 45 minute cylinder should have an internal volume of approximately 6.8 liters (418 cubic inches) in order to hold 1,800 liters of free air when loaded at 31 MPa (4,500 psig). By changing the charge pressure to 38 MPa (5,500 psig), the internal volume of the cylinder can be reduced by approximately 1.1 liters (69 cubic inches), or 17%, while still maintaining the desired free volume of 1,800 liters. By decreasing the volume of the cylinder by 17%, a proportional reduction in the external dimensions of the cylinder can be achieved (see, for

ES 2 706 450 T3 example, figure 4). In an exemplary embodiment, the disclosed 45-minute cylinder 12, loaded at approximately 38 MPa (5,500 psig), may have the same external dimensions as a traditional 30-minute cylinder pressurized at 31 MPa (4,500 psig). ).

As noted above, the inventors have found that simply continuing to increase the loading pressure (eg, 41 MPa (6,000 psig) and above) does not result in commensurate savings in space and weight. This can be seen in Figure 6, which shows that to obtain an additional 1.1 liters (69 cubic inches) (17%) decrease in cylinder volume (over that obtained with a loading pressure of 38 MPa (5,500 psig)), a cylinder charge pressure of approximately 50 MPa (7,250 psi) would be required (approximately a 32% increase in charge pressure). This is shown for each of the closed cylinders 10, 12, 14 in Figure 10 (will be explained in more detail below). What can be seen from these data is that increases in cylinder charge pressure above 41 MPa (6,000 psig) result in continuous decreases in charge efficiency (i.e., further reductions in the volume of the cylinder). cylinder require substantial increases in head pressure). Additionally, increasing loading pressures above 41 MPa (6,000 psig) also produces substantial undesirable weight gains, due to the large wall thicknesses required to contain such higher pressures.

Figure 7 is a graph of the first derivative of the graphs of Figures 5 and 6, illustrating the rate of volume change (liters / MPa (cubic inches / psi)) as a function of head pressure. This graph further illustrates how the curve begins to flatten substantially at approximately 41 MPa (6,000 psig), supporting the idea that loading a cylinder above approximately 41 MPa (6,000 psig) results in substantially less return in terms of reduction. cylinder volume and therefore size.

It will be appreciated that, although the graphs in Figures 5-7 provide specific values ​​related to a 1,800 liter cylinder (i.e. 45 minutes), similar results are obtained for cylinders of other sizes (i.e. 30 minutes, 60 minutes and 75 minutes). Furthermore, it will be appreciated that the disclosed cylinders need not be provided in the discrete capacities mentioned above, but could be provided in a wide variety of other incremental capacities, as desired (e.g., 35 minutes, 50 minutes, 62 minutes, etc.)

Referring now to FIG. 8, an exemplary graph of cylinder length (L) versus diameter (d) is shown for the disclosed cylinders 10-16. Although the specific values ​​illustrated in Figure 6 refer to a 45 minute cylinder (1,800 liter free air volume), the formula is applicable to 30 minute, 60 minute and 75 minute cylinders as well. The graph indicates that the desired cylinder size and weight reductions can be obtained in cylinders 12 through 16 by selecting the length or diameter based on the following equation:

<img file="ES2706450T3_D0001.tif" />

in which:

L = length,

V = volume of water and d = diameter.

It will be appreciated that volume of water, as used in the above formula, refers to the internal physical volume of the associated cylinder 10-16, and not to the volume of free compressed air in the cylinder. Also, it will be appreciated that the values ​​of Lmax, Lmin, dmax and dmin (as well as the resulting selected L and d) represent the internal dimensions of the pressure volume portion of cylinder 12. As noted, the curve in Figure 8 is represented by equation (1), bounded by the values ​​of Lmax, Lmin, dmax, and dmin, and therefore the disclosed cylinder 12 may have a length L and a diameter d that falls on the curve between Lmax, Lmin, dmax and dmin. Using the curve and formula, the dimensions of cylinder 12 can be obtained to obtain a cylinder which, when loaded to 38 MPa (5,500 psig), contains a volume of free air of approximately 1,800 liters (i.e., a supply of air 45 minute breathable). It will be appreciated that Equation (1) applies to a cylinder having hemispherical heads (ie ends). Therefore, if the cylinder includes square, ellipsoidal, or hemispherical heads, then Lmin / Lmax and dmin / dmax values ​​other than those indicated in this document may apply.

In an exemplary embodiment, applicable to a 45 minute cylinder (i.e. second cylinder 12), Lmax can be about 49.5 cm (19.5 inches), Lmin can be about 42.9 cm (16.9 inches), dmax can be about 13.7 cm (5.4 inches) and dmin can be about

ES 2 706 450 T3

12.7 cm (5.0 inches), where Lmax, Lmin, dmax, and dmin represent the Internal dimensions of the pressure volume portion of cylinder 12. In an exemplary embodiment, Lmax and dmax are defined as the length and the diameter of a conventional cylinder of 45 minutes (ie, 31 MPa (4,500 psig)). The disclosed cylinder 12 can be selected to have a length equal to Lmax, which, according to Equation (1) and Figure 8, would result in a diameter equal to dmin. The resulting cylinder 12 would have a smaller diameter than the traditional 45 minute cylinder. Alternatively, the disclosed cylinder 12 may be selected to have a diameter equal to dmax, which according to Equation (1) and Figure 8 would result in a length equal to Lmin. The resulting cylinder 12 would have a length less than that of the traditional 45 minute cylinder. Various other embodiments are contemplated in which the length and diameter of the disclosed cylinder 12 would be at a point on the curve between some combination of Lmax, Lmin, dmax, and dmin.

By selecting the length and diameter of cylinders 10 through 16 in accordance with Equation (1), weight reductions from about five percent (5%) to about twelve percent (12%) or more can be achieved with cylinders 10 to 16 disclosed compared to standard 31 MPa (4,500 psig) air cylinders (see Figure 10).

Figure 9 is an exemplary three-dimensional graph of cylinder length versus cylinder diameter and cylinder weight for an exemplary 45 minute (1,800 liter) cylinder 12 loaded at 38 MPa (5,500 psig) . As noted above, the cylinder diameter and cylinder length values ​​represent the internal dimensions of the pressure volume portion of cylinder 12. As with the curve of Figure 8, the illustrated three-dimensional surface of Figure 9 may allow the selection of an appropriate cylinder based on particularly selected maximum and minimum values ​​of length, diameter and weight. Therefore, the disclosed cylinder 12 may have a Length L, a diameter d, and a weight W falling within the surface within the area bounded by the points dmin, Lmax, Wmax; dmin, Lmax, Wmin; dmax, Lmin, Wmin; and dmax, Lmin, Wmax. In Figure 8, an exemplary dot 120 is shown within this area, illustrating an appropriate combination of length, diameter, and weight. In one embodiment, Wmax is no greater than the weight of a conventional 4,500 psig (31 MPa) cylinder having the same air capacity.

Using the surface of Figure 9, the dimensions of cylinder 12 can be obtained to result in a cylinder which, when loaded at 38 MPa (5,500 psig), contains a volume of free air of approximately 1,800 liters (that is, a supply 45 minutes of breathing air).

Figure 10 is a graph showing comparative values ​​of water volume, length, diameter, radius, length, and weight for 30, 45, and 60 minute cylinders. It should be noted that the weight values ​​(W, Wmax, Wmin) of cylinders 10 to 16 disclosed were calculated using assumed wall thicknesses of approximately approximately approximately known, of known, of known, and of Los values ​​of

0.818 cm (0.322 in) for the 30 minute cylinder 10 given

0.866 cm (0.337 in) for 45 minute cylinder 12 given

0.919 cm (0.362 inch) for the 60 minute roll given to about 1.01 cm (0.398 inch) for the 75 minute roll 16 disclosed.

Weights of the 4,500 psig (31 MPa) cylinders were calculated using an assumed wall thickness of approximately 0.263 in. (0.668 cm) for a conventional 4500 psig (31 MPa) 30-minute cylinder of 0.317 in. (0.805 cm). for a 45-minute cylinder of 4500 psig (31 MPa) conventional and 0.892 cm (0.351 in.) for a 60-minute conventional 31 MPa (4500 psig) air cylinder. These wall thicknesses can include the combination of an inner liner, a cover, and any other layer that can be used to construct cylinders of this type.

As can be seen, the volume of water decreases by being associated with each of the disclosed cylinders 10, 12, 14, resulting in a substantial increase in weight compared to corresponding conventional air cylinders of capacities. similar open air. Therefore, any weight added to cylinders 10 through 16 that is disclosed as a result of the reinforcement required to accommodate the higher pressures (compared to conventional 31 MPa (4,500 psig) cylinders) also results in cylinders that weigh less than corresponding conventional cylinders. Also, substantial length and / or diameter reductions are illustrated.

Figure 10 also includes a tabulation of the compressed volume change, both in cubic centimeters (cubic inches) reduced and in percent reduction, for various embodiments of cylinders 10, 12, 14 disclosed loaded at different operating pressures. (For example, 34 MPa (5,000 psig), 38 MPa (5,500 psig), 41 MPa (6,000 psig). As noted above, these data show that the disclosed cylinders provide a desirable balance between internal cylinder volume reduction, external dimensional reduction, weight reduction, and loading pressure. The data shows that simply continuing to increase the charging pressure above about 41 MPa (6,000 psig) results in an undesirable decrease in charging efficiency.

Furthermore, for specific 10, 12, 14 and 16 cylinder realizations of 30 minutes (1,200 liters), 45 minutes (1,800 liters), 60 (2,400 liters) and 75 minutes (3,000 liters), specific example values ​​Lmax are provided, Lmin, Dmax, Dmin, Wmax and Wmin. The values ​​Lmax, Lmin, Dmax and Dmin represent the internal dimensions of the pressure volume portion of the respective cylinders 10 to 16. As explained above, at 8

In order to provide a range of desirable length, diameter and weight values, a particular cylinder can be designed to include a desired free air volume, a desired weight and a desired outer space envelope. In some embodiments, it may be desirable to minimize weight. In such cases, the value of Wmin can be selected as the value for weight, and the length and diameter values ​​can remain within Lmin / Lmax, dmin / dmax according to Equation (1). In other embodiments, it may be desirable to minimize the diameter (eg, reduce the effect of rotation between the parts). In such cases, the dmin value can be selected as the diameter, and the length and weight values ​​can be adjusted to stay within Lmin / Lmax, Wmin / Wmax according to Equation (1). It will be appreciated that Equation (1) extends to a cylinder having hemispherical heads (ie ends). Therefore, if the cylinder includes square, ellipsoidal or hemispherical heads, then different values ​​of Lmin / Lmax and dmin / dmax can be applied to those indicated in figure 10.

An exemplary side-by-side comparison of the disclosed dimensions of cylinders 10-16 compared to traditional 31 MPa (4,500 psig) cylinders is shown in Figure 11.

Example 1 - 30 minute air cylinder comparison

A 30 minute conventional 30A air cylinder was manufactured with a 31 MPa (4,500 psig) operating pressure. The 30A conventional air cylinder had a weight of 2.99 kg (6.6 pounds), an outer length of 47.12 cm (18.55 inches), and an outer diameter of 14.05 cm (5.53 inches). . A 30 minute air cylinder 10 according to claim was manufactured with an operating pressure of 38 MPa (5,500 psig). The air cylinder 10 had a weight of 2.63 kg (5.8 pounds), an outer length of 48.00 cm (18.9 inches), and an outer diameter of 12.55 cm (4.94 inches).

Example 2 - 45 minute air cylinder comparison

A 45-minute 45A conventional air cylinder was manufactured with a service pressure of 31 MPa (4,500 psig). Conventional cylinder 45A had a weight of 4.08 kg (9.0 lbs), an external length of 46.23 cm (18.20 inches), and a diameter of 17.37 cm (6.84 inches). A second conventional air cylinder 45B was manufactured with an outer length of 52.83 cm (20.80 inches) and an outer diameter of 16.05 cm (6.32 inches). A 45 minute air cylinder 12 was manufactured in accordance with the invention with a service pressure of 38 MPa (5,500 psig). Air cylinder 12 had a weight of 3.54 kg (7.8 lbs), an outer length of 47.75 cm (18.8 inches), and an outer diameter of 15.49 cm (6.10 inches).

Example 3 - 60 minute air cylinder comparison

A 60-minute 60A conventional air cylinder was manufactured with a service pressure of 31 MPa (4,500 psig). Conventional cylinder 60A had a weight of 5.26 kg (11.6 pounds), an outer length of 55.12 cm (21.70 inches), and an outer diameter of 17.91 cm (7.05 inches). A 60 minute air cylinder 14 was manufactured with a service pressure of 39 MPa (5,500 psig). The 60 minute cylinder 14 had a weight of 4.54 kg (10.0 lbs), an outer length of 53.87 cm (21.21 inches), and an outer diameter of 16.59 cm (6.53 inches). .

Example 4 - 75 minute air cylinder comparison

Conventional 75 minute (31 MPa (4,500 psig) service pressure) air cylinders were not manufactured because the required length and diameter dimensions were considered excessive for SCBA applications. A 75 minute air cylinder 16 was manufactured in accordance with the invention with a service pressure of 38 MPa (5,500 psig). The 75 minute cylinder had a weight of 5.67 kg (12.5 pounds), an outer length of 55.75 cm (21.95 inches), and an outer diameter of 18.16 cm (7.15 inches). Although there are no comparative data for the conventional 75 minute cylinders, it can be seen that the disclosed 75 minute cylinder 16 is compared to the operating pressure of the conventional 60 minute cylinder (31 MPa (4,500 psig)) both in diameter as well as in length.

The disclosed cylinders 10-16 can be manufactured using any of a variety of materials, including aluminum, steel, carbon fiber, and / or fiberglass wrapped in aluminum or steel, and the like. In addition, other composite materials can also be used.

Sized in this way, the disclosed air cylinders can provide the user with greater maneuverability, a longer duration of the air supply, a lower center of gravity (for shorter cylinders), a closer positioned center of gravity from the rear of the user (for cylinders having smaller diameters). Ultimately, the disclosed cylinders can provide a user with increased comfort and mobility in a confined space.

Referring now to Figure 12, a schematic of an example SCBA 18 includes a single air cylinder 12 that is mounted on a harness or frame 26 to allow its air cylinder 12 to be carried on the firefighter's back. The air cylinder 12 is connected to a first regulating valve 20, which in turn is connected to a second regulating valve 22. The second regulating valve 22 is connected to a mask 24 that can be used by a firefighter. The air cylinder 12, the first regulating valve 20, the 9

ES 2 706 450 T3 second regulating valve 22 and mask 24 are in fluid communication with each other through one or more hoses 25.

The first regulating valve 20 reduces the air pressure in the air cylinder 12 to a predetermined level. The second regulating valve 22 provides a regulated flow of air to the firefighter at a very low pressure below the predetermined level through the mask 24. The second regulating valve 22 operates in a demand mode, in which the second regulating valve 22 is only activated when the firefighter inhales, or in a continuous positive mode, in which the second regulating valve 22 provides a flow of constant air to mask 24.

It will be appreciated that any of the disclosed air cylinders 10-16 could be used with the SCBA 18 described above. It will also be appreciated that the disclosed arrangement advantageously allows an SCBA to employ a single air cylinder having a free air capacity, while reducing the space and total space envelope compared to conventional air cylinders. (i.e. 31 MPa (4,500 psig)) that have similar free air capabilities.