Abstract:
The High Pressure Flow Indicating Switch devise and method is used to monitor the flow of a gaseous, liquid or finely divided solid material through pipes, tubing or equipment. This devise is an improvement over technology available at the present time due to its accuracy over an extremely wide range of pressure/flow, simplicity of operation and low cost to manufacture. This High Pressure Flow Indicating Switch is primarily comprised of a pressure confining cylinder housing through which a magnetic field can pass with minimal distortion, a piston containing a magnetic source which emits a magnetic field and a reed/proximity switch mounted to the exterior of the pressure cylinder housing which monitors the position of the magnetic field. As a liquid or gas passes through the cylinder housing, the piston with its magnetic field is displaced and moves in the direction of the material flow. Electrical contacts within the reed/proximity switch are activated by the subsequent magnetic field alignment thus indicating a “Flow” or “No Flow” condition.

Description:
[0001]    This application claims priority from provisional application No. 61/4000,862 filed on Aug. 4, 2010 which has the confirmation number of 8615 
     
    
     SUMMARY 
       [0002]    Most high pressure (pressures greater than 1500 psi) flow indicating switches, which are available at the present time, determine the flow of a gaseous or liquid material flowing through a pipe or tube using the following method. 
         [0003]    A restricting orifice is placed in the pipe or tube and as the gaseous or liquid material passes through this orifice, the pressure drop (or vacuum) on the immediate downstream side of this orifice is measured. This pressure drop (or vacuum) is then used to determine the velocity or volume/quantity of the material which is flowing through the pipe or tube. 
         [0004]    The technical aspects of design and manufacture of this type of system are very complicated and expensive to produce. Also, this method does not retain flow accuracy over a wide range of pressures and is susceptible to failure caused by contaminants in the flow stream such as moisture, dirt or grit. 
         [0005]    The high pressure flow indicating switch device and method presented in this patent application is an alternative to the standard design of flow indicating switches which are available at the present time and discussed briefly in the above three paragraphs. 
         [0006]    The proposed flow indicator switch is used to determine if the flow of a gaseous or liquid material through a pipe, tube or equipment has been stopped at any point upstream or downstream of the flow indicating switch. Most flow indicating devices presently available will be adversely affected by the resulting pressure buildup caused by the interruption of flow of a gaseous or liquid material downstream of the devise. 
         [0007]    Since the flow indicating switch proposed in this patent application relies on the flow of a material and not pressure, the slowing or stoppage of the material flow downstream of the high pressure flow indicating switch and subsequent pressure buildup will have no adverse reactions or effect on its operation. The high pressure flow indicating switch has a very simple operating principle. High pressure gaseous or liquid material flowing through a pressure housing displaces (moves) a spring loaded poppet piston which contains a magnetic source. The position of this magnetic source is sensed by a reed/proximity switch which is mounted on the exterior of the pressure housing. The alignment of the magnetic source and the reed/proximity switch electrical will the either open or close the contacts. The opening or closing of these contacts will “make” or “break” the electrical circuit of the reed/proximity switch. The making or breaking of this electrical circuit will indicate whether a material is passing through the flow indicating switch. As flow of the material through the flow indicating switch housing slows or stops completely, the poppet piston return spring pressure will push the poppet piston back into its normally closed position thus “making” or “breaking” the electrical circuit that material has stopped passing through the flow indicating switch. 
         [0008]    The quantity of material flow through the flow indicator switch required to displace the poppet and activate the reed/proximity switch can be adjusted by increasing or decreasing the clearance between the poppet piston nose and the orifice into which the poppet nose rests or changing the poppet piston return spring pressure. 
         [0009]    The flow indicating switch can be converted to a check valve with the addition of an o-ring to the base of the poppet piston nose. The flow indicating characteristics and operation of the switch will not change by this addition however now the high pressure flow indicating switch will now have the secondary function of acting as a flow check valve which will prevent the material flow from reversing and moving upstream in the event that the downstream pressure becomes greater than that of the upstream pressure. 
         [0010]    The high pressure flow indicating switch can also be converted to a pressure holding regulator designed to hold a minimal predetermined residual pressure upstream of the switch by simply adding a check ball/spring assembly to the interior of the poppet piston. 
         [0011]    Some of the benefits of this new design flow indicator switch are 1—reliability, 2—accuracy through a wide pressure/volume range, 3—manufacturing simplicity, 4—inexpensive to produce, 5—functionality remains unaffected by pressure buildup created when downstream flow is blocked and 6—not as susceptible to failure due to dirt, grit or corrosion. 
         [0012]    This design of high pressure flow indicating switch can be used to monitor the flow of any pneumatic, hydraulic or finely divided solid materials through a pipe, tube or housing. However, the primary purpose of its design is to make possible the construction of an efficient, reliable and low cost auto-cascade system used to recharge SCBA and SCUBA cylinders used by Fire Fighters and SCUBA divers. 
         [0013]    To accomplish the construction of the auto-cascade system mentioned in the above paragraph, the high pressure flow indicating switch will be used to determine whether the flow of compressed breathing air is present through the various parts of the auto-cascade system and then accurately activate the discharge sequence of the various stages of an electric, electric over pneumatic or electric over hydraulic operated cascade storage system. The output/discharge of this auto-cascade system will be used to recharge self contained breathing apparatus (SCBA) or self contained under water breathing apparatus (SCUBA) cylinder(s). (See  FIG. 7 .) 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0014]    FIG.  1 —Sectional view of the basic flow indicating switch design. 
           [0015]    FIG.  2 —Two states of a flow indicating switch in use. Flow and no flow. 
           [0016]    FIG.  3 —Variation of  FIG. 1  which has a higher accuracy at all flows. 
           [0017]    FIG.  4 —Variation of  FIG. 3  which uses a secondary poppet piston which is enclosed in the primary poppet piston. 
           [0018]    FIG.  5 —Variation of  FIG. 1  with poppet piston to cylinder o-ring seal. 
           [0019]    FIG.  6 —Variation of  FIG. 4  which is used to regulate/hold back pressure upstream of the flow indicating switch. 
           [0020]    FIG.  7 —Schematic of a self sequencing automatic cascade system used for recharging SCBA breathing air cylinders which uses the high pressure flow indicating switch shown in  FIG. 1  as the key operating component. 
       
    
    
     DETAILED DESCRIPTION 
     FIG. 1 
       [0021]    The  9 A-gasket or o-ring seal between the  1 A-pressure cylinder housing cap and  2 A-pressure cylinder housing ensures a tight flow and pressure seal so that material flowing into and through the high pressure flow switch cannot leak outside of the flow switch. 
         [0022]    As a compressed gaseous or liquid material enters the  15 A-inlet of the  1 A-cylinder housing cap it will come into contact with the  11 A-poppet piston nose. As the flow through the clearance between the  11 A-poppet piston nose and  12 A-poppet nose receiving orifice exceeds a predetermined amount, which is determined by the clearance between the  11 A-poppet piston nose and  12 A-poppet nose receiving orifice and/or  14 A-poppet return spring pressure, the  11 A-poppet nose and  3 A-poppet will overcome the  7 A-poppet spring pressure and push the  11 A-poppet piston nose clear of the  12 A-poppet nose receiving orifice. When this happens the  5 A-reed/proximity switch which, is secured to the exterior of the  2 A-pressure housing, will detect the movement of the magnetic field generated by the  6 A-magnet which is mounted on the interior or exterior of the  3 A-poppet piston. The alignment of the magnetic field generated by  6 A-magnet will cause the electrical contacts within the  5 A-reed/proximity switch to open or close. The opening or closing of the  5 A-reed/proximity switch electrical contacts will complete an electrical circuit. The “making” or “breaking” of this electrical circuit will be used to indicate that material is flowing through the high pressure flow indicating switch. 
         [0023]    The gaseous or liquid material flowing past the  11 A-poppet piston nose will travel past or through the first  17 A-poppet piston skirt and then through a  13 A-hole in the  3 A-poppet piston then through the  14 A-spring recess where it will then be discharge through the flow indicating switch  16 A-outlet. 
         [0024]    As the material flowing through the flow indicating switch decreases to, or below, the predetermined volume, the  7 A-poppet return piston spring will push the  3 A-poppet piston to its normally closed or “no flow” position. The ensuing misalignment of the magnetic field generated by  6 A-magnet and the  5 A-reed/proximity switch will cause the electrical contacts within the  5 A-reed/proximity switch to open or close. The opening or closing of the  5 A-reed/proximity switch contacts will complete an electrical circuit. The “making” or “breaking” of this electrical circuit will indicate that “no flow” is present within the flow indicating switch. 
         [0025]    If the pressure downstream of the high pressure flow indicating switch becomes greater than that of the upstream pressure, the  8 A-O-ring will seat against the  3 A-poppet piston and the  1 A-cylinder housing cap thus causing the flow indicating switch to convert to a check valve. 
         [0026]    NOTE: The  8 A-check valve O-ring may be omitted if the check valve function of this switch is not desired. 
         [0027]    NOTE: The flow/volume which will activate or deactivate the high pressure flow indicating switch can be increased or decreased by the altering the clearance between the  11 A-poppet piston nose and the  12 A-poppet nose receiving orifice and/or changing the  7 A-poppet piston return spring pressure. 
         [0028]    NOTE: An alternate to the manufacturing of this flow indicating switch would be that the  3 A-poppet piston and  7 A-spring could be reversed and the  12 A-poppet nose receiving orifice could be located in the  2 A-cylinder pressure housing. If this manufacturing procedure is used the  16 A-discharge opening would then become the  15 A-inlet. 
       FIG. 2 
       [0029]    The two drawings on this page show a flow indicator switch in a “No Flow” and “Flow” position. While drawing “B” shows the reed/proximity switch in a normally open condition with no flow passing through the flow indicating switch, a normally closed reed/proximity switch could be used for the “no flow” position. 
         [0030]    Drawing “B” shows a flow indicating switch which has no flow passing through it. The  2 B-poppet piston is seated and in the check valve position so that pressure/material back flow is not possible. The magnet  3 B is not aligned with  4 B-reed/proximity switch and the  5 B-electrical contacts are in the normally open position. 
         [0031]    Drawing “C” demonstrates a material (either gaseous, liquid or finely divided solids) flowing through the flow indicating switch. Material flow enters the  1 C-inlet will first run into resistance from  2 C-poppet nose which is seated in the  3 C-poppet nose receiving orifice. As the flow volume increases to a point above the predetermined quantity, which is established by the clearance between the  2 C-poppet noses and the  3 C-poppet nose receiving orifice and/or  12 C-poppet piston return spring tension, the  4 C-poppet piston will move in the direction of the material flow. As the  4 C-poppet piston nears the end of its travel the  5 C-poppet piston magnet will align with the  6 C-reed/proximity switch which in turn will close the  6 C-reed/proximity switch  7 C-contacts to complete the electrical circuit. This electrical signal will be used to indicate that flow through the flow indicating switch is present. 
         [0032]    As the  4 C-poppet piston nears its maximum travel the material flow will travel past the  2 C-poppet piston nose, around or through the  10 C-first poppet piston skirt, along the body of the  4 C-poppet piston and into the  9 C-piston lower orifice. The material will then enter the  11 C-poppet piston spring recess and will then discharge through the  8 C-discharge opening. 
       FIG. 3 
       [0033]    A tight seal between the upstream and downstream sides of the high pressure flow indicating switch is accomplished by the  39 D-secondary poppet piston head seating against the  40 D-O-ring which in turn is seated against the to the  37 D-primary poppet piston and the  42 D-O-ring which seals the  37 D-primary poppet piston the  36 D cylinder wall housing. 
         [0034]    As the flow pressure of a compressed gas, liquid or finely divided solid material entering the  45 D-inlet increases above a predetermined point, which is set by the  41 D-primary poppet piston return spring, the  37 D-primary poppet piston assembly will move downstream with the flow of the material to the near “open position”. As the piston assembly approaches the near “open” position, the bottom of the  38 D-secondary poppet piston strikes the  35 D-housing cap. As the piston assembly reaches the “fully open” position, the  39 D-secondary poppet piston head and  40 D-O-ring are forced away from the  37 D-primary piston thus allowing material to flow through the  47 D-secondary poppet piston internal material passage and exiting through the  46 D-outlet. 
         [0035]    When the  37 D-primary poppet assembly nears its “fully open” position the magnetic field of the  33 D-magnet, which is attached to and moves with the  37 D-primary poppet piston assembly, aligns with the  43 D-reed/proximity switch thus opening or closing the reed/proximity switch electrical contacts. The opening or closing of the  43 D-reed/proximity switch contacts will complete an electrical circuit. The “making” or “breaking” of this electrical circuit will indicate that “flow” is present within the flow indicating switch. 
         [0036]    As the material flow through the high pressure flow indicating switch slows or stops completely the  41 D-primary poppet piston return spring moves the piston, magnet and its magnetic field to the “closed” position, which in turn will open or close the  43 E-reed/proximity switch electrical contacts. The electrical signal from the  43 E-reed/proximity switch will indicate that the piston assembly is in the “closed” position and that “no flow” is presently passing through the high pressure flow indicating switch. 
         [0037]    As the differential pressure/flow downstream of the flow indicating switch increases to a point where it is greater than the upstream pressure, the increasing pressure assists the  41 D-spring and forces the  37 D-primary piston upstream which causes the  37 D-primary poppet piston to seat to the  40 D-O-ring between it that the  39 D-secondary poppet piston head. At the same time the  39 D-secondary poppet piston head will seat against the  44 D-O-ring and the  36 D-Cylinder wall housing thus converting the flow indicating switch into a check valve. 
         [0038]    NOTE: The  44 D-check valve O-ring may be omitted if the check valve function of this switch is not desired. 
         [0039]    NOTE: Flow volume/pressure required to open the high pressure flow indicating switch can be adjusted by adjusting the  41 D-piston spring pressure. 
       FIG. 4 
       [0040]    A tight seal between the upstream and downstream sides of the flow indicating switch is accomplished by the  24 E-O-ring sealing the  32 E-cylinder wall housing to the  25 E-upper primary poppet piston and the flow/differential pressure forcing the  27 E-secondary poppet piston down which will cause the  28 E-poppet piston o-ring to make a seal against the  26 E-lower primary poppet piston internal shoulder. 
         [0041]    As the flow of a material (either compressed gas, liquid or finely divided solid) entering the  35 E-inlet, increases above a predetermined point, which is set by the  30 E-primary poppet piston return spring, the  25 E-primary poppet piston assembly will move downstream with the flow of the material to the near “open position”. As the piston assembly approaches the near “open” position, the bottom of the bottom of the  27 E-secondary poppet piston strikes the  23 E-housing cap. As the piston assembly reaches the “fully open” position, the  27 E-secondary poppet piston head and  28 E-O-ring are forced away from the  26 E-lower primary piston thus allowing material to flow through the  37 E-poppet piston nose orifice, into and through the  37 E-secondary poppet piston internal passage and exit through the  36 E-outlet. 
         [0042]    As the  25 E-primary poppet assembly nears its “fully open” position, the magnetic field of the  33 E-magnet, which is attached to and moves with the  25 E-primary poppet piston assembly, aligns with the  34 E-reed/proximity switch, the  34 E-reed/proximity switch contacts will either open or close. The opening or closing of the  34 -reed/proximity switch contacts will “make” or “break” an electrical circuit. The “making” or “breaking” of this electrical circuit will indicate that “flow” is present within the flow indicating switch. 
         [0043]    As the material flow through the high pressure flow indicating switch slows or stops completely the  30 E-primary poppet piston return spring moves the piston, magnet and its magnetic field to the “closed” position, which in turn will open or close the  34 E-reed/proximity switch electrical contacts. The electrical signal from the  34 E-reed/proximity switch will indicate that the piston assembly is in the “closed” position and that “no flow” is presently passing through the high pressure flow indicating switch. 
         [0044]    As the differential pressure/flow downstream of the flow indicating switch increases to a point where it is greater than the upstream pressure, the increasing pressure assists the  30 E-spring and forces the  25 E-primary piston assemble toward the upstream flow which causes the  25 E-primary poppet piston to seat the  31 E-O-ring between it and the  32 E-cylinder wall housing. At the same time the  27 E-secondary poppet piston head will seat against the  29 E-O-ring to the top of the  25 E-primary poppet piston interior thus converting the flow indicating switch into a check valve. 
         [0045]    NOTE: Flow volume/pressure required to open the high pressure flow indicating switch can be adjusted by changing the  30 E-piston spring pressure. 
         [0046]    NOTE: The  29 E-check valve O-ring and the  29 E-O-ring may be omitted if the check valve function of this switch is not desired. 
       FIG. 5 
       [0047]    As the material (either compressed gas, liquid or finely divided solid) entering the  10 E-inlet and flowing through the high pressure flow indicting switch exceed a predetermined quantity, which is set by the  8 F-poppet piston return spring and the  5 F-poppet piston bypass orifices, a pressure/flow buildup will occur in the  2 F-cylinder between the  1 F-cylinder cap and the  3 F-poppet piston. When the pressure/flow buildup is sufficient to exceed the flow handling capabilities of the  5 F-poppet piston bypass orifices and overcome the  8 F-poppet piston return spring, the  3 F-poppet piston will move downstream in the direction of the flow of the material to its near “open position”. 
         [0048]    As the  3 F-primary poppet assembly nears its “fully open” position, the magnetic field of the  6 F-magnet, which is attached to and moves with the  3 F-poppet piston, aligns with the  9 F-reed/proximity switch, the  9 F-reed/proximity switch electrical contacts will either open or close. The opening or closing of the  9 F-reed/proximity switch contacts will complete an electrical circuit. The “making” or “breaking” of this electrical circuit will indicate that “flow” is present within the flow indicating switch. 
         [0049]    As the  3 F-poppet piston reaches the “fully open” position, the increase of differential pressure between the upstream and downstream sides of the  3 F-poppet piston, the flowing material will be forced through the  5 F-poppet piston bypass orifices allowing material to flow exit through the  11 F-outlet. 
         [0050]    As the differential pressure downstream begins to equalize with upstream pressure, the  8 F-poppet piston return spring will move the  3 F-poppet piston to the “closed” position. As the  3 F-poppet piston &amp;  6 F-magnet moves to the “closed” position the magnetic field generated by the  6 F-magnet will move and open or close the  9 F-reed/proximity switch electrical contacts. The opening or closing of the  9 F-reed/proximity switch contacts will complete an electrical circuit. The “making” or “breaking” of this electrical circuit will indicate that “no flow” is present within the flow indicating switch. 
         [0051]    As the differential pressure downstream of the flow switch increases to a point where it is greater than the upstream pressure, the  7 F-check valve o-ring seats against the cap thus converting the flow indicating switch into a check valve. 
         [0052]    NOTE: A predetermined amount of material flow through a “closed” high pressure flow indicating switch will be present at all times. 
         [0053]    NOTE: The amount of material flow through the switch while in the “closed” position or to “open” the high pressure flow indicating switch can be adjusted by changing the  5 F-poppet piston bypass orifices and/or changing the spring tension of the  8 F-poppet return spring. 
         [0054]    NOTE: The  7 F-check valve O-ring may be omitted if the check valve function of this switch is not desired. 
       FIG. 6 
       [0055]      FIG. 6  demonstrates the high pressure flow indicating switch which has been configured to also function as a back pressure regulator/holding valve. The check ball assembly, consisting of the  18 G-check ball,  20 G-check ball seat O-ring,  19 G-check ball seat and  17 G-check ball spring, is held in place between the  15 G-upper poppet piston housing and the  22 G-lower poppet piston. In the closed position, a tight seal between the upstream and downstream sides of the flow indicating switch is accomplished by the  26 G-O-ring sealing the  12 G-cylinder wall housing to the  15 G-upper primary poppet piston and the  17 G-checkball spring which seating the  18 G-checkball to the  19 G-checkball seat. 
         [0056]    As the flow of a material (either compressed gas, liquid or finely divided solid) entering the  23 G-inlet, increases above a predetermined point, which is set by the  16 G-primary poppet piston return spring and the  17 G-checkball spring pressure, the  15 G-primary poppet piston assembly will move downstream with the flow of the material to the near “open position”. 
         [0057]    As the  15 G-primary poppet assembly nears its “fully open” position, the magnetic field of the  14 G-magnet, which is attached to and moves with the  15 G-primary poppet piston assembly, aligns with the  13 G-reed/proximity switch opening or closing the  13 G-reed/proximity switch electrical contacts. The opening or closing of the  13 G-reed/proximity switch electrical contacts will “make” or “break” an electrical circuit. The “making” or “breaking” of this electrical circuit will indicate that “flow” is present within the flow indicating switch. 
         [0058]    Once the upstream to downstream pressure differential is sufficient to overcome the  17 G-check ball spring tension, material will flow into  25 G-poppet piston nose orifice, pushing past the  18 G-check ball and then exiting the high pressure flow indicating switch through the  24 G-outlet. 
         [0059]    As the differential pressure downstream begins to equalize with upstream pressure, the  17 G-check ball return spring will move the  18 G-check ball to the “closed” position. As the pressure differential reaches near equalization, pressure applied by the  16 G-primary poppet piston return spring will move the  15 F-primary poppet piston assembly to the “closed” position. 
         [0060]    As the  15 G-primary poppet assembly nears its “closed” position, the magnetic field of the  14 G-magnet, which is attached to and moves with the  15 G-primary poppet piston assembly, misaligns with the  13 G-reed/proximity switch, the  13 G-reed/proximity switch electrical contacts will either open or close. The opening or closing of the  13 G-reed/proximity switch electrical contacts will “make” or “break” an electrical circuit. The “making” or “breaking” of this electrical circuit will indicate that “no flow” is present within the flow indicating switch. 
         [0061]    If the differential pressure downstream of the flow indicating switch increases to a point where it is greater than the upstream pressure, the  21 G-check valve o-ring is forced to seat against the  12 G-cylinder pressure housing and the  17 G-checkball spring seats the  18 G-checkball to the  19 G-checkball seat thus converting the flow indicating switch into a check valve. 
         [0062]    NOTE: The pressure at which the high pressure flow indicating switch will indicate flow can be adjusted by changing the  16 G spring pressure. The holding pressure, at which the high pressure flow indicating switch will allow material to pass through, and still maintain the minimal upstream material pressure, can be adjusted by changing the  17 G-checkball spring pressure. 
       FIG. 7 
       [0063]    This figure demonstrates a 3-stage auto-cascade system which uses the High Pressure Flow Indicating Switch as the key component used to accurately control the sequential discharge of compressed gas storage cylinders into a cylinder which is being recharged. 
         [0064]    Basic gas flow mapping: The flow from the  44 H-low pressure storage cylinder will flow through the  52 H and  53 -high pressure flow indicating switches. The flow from the  45 H-medium pressure storage cylinder will pass through the second stage  50 H-electric over pneumatic solenoid valve and then flow through the  53 H-high pressure flow indicating switch. And the flow from the  46 H-high pressure storage cylinder will flow directly to the  62 H-pressure reducing regulator. 
         [0065]    The pressure from the three storage cylinders will flow through the  62 H-pressure regulator which will reduce the incoming compressed air/gas pressure to the correct pressure which is required by the SCBA cylinder being recharged. The reduced air/gas pressure then flows downstream where its flow is stopped by the  54 H-bock valve. 
         [0066]    Actual operational results: A  55 -SCBA/SCUBA cylinder is connected downstream of the “closed”  54 H-block valve which is located just downstream of the  62 -pressure reducing regulator. Since the  54 H-block valve is closed, no compressed air/gas will be flowing through the  52 H or  53 H-flow indicating switch thus their respective  50 H and  51 H-electric over pneumatic solenoid valves will remain in their “normally open” position allowing pressure/flow from the  44 H,  45 H and  46 H-storage cylinders to move downstream through their respective  47 H,  48 H,  49 H-tubing. The  44 H-low pressure storage cylinder shall be connected directly to the  58 H-tubing. The  45 H-medium pressure storage cylinder will be connected to the  50 H-second stage solenoid valve and the  46 -high pressure storage cylinder will be connected to the  51 H-third stage solenoid valve. 
         [0067]    When the  54 H-block valve is opened compressed air/gas from the  44 H-low pressure storage cylinder will flow downstream through the  58 -tubing. As the compressed air/gas flows downstream through the  58 -tubing it will pass through the  52 H-second stage flow indicating switch which will initiate and send an electric current which will close the  50 H-second stage solenoid valve which will prevent downstream flow from the  45 H-medium pressure storage cylinder. The compressed air/gas will then flow through the  53 H-third stage flow indicating switch which will initiate and send an electric current which will close the  51 H-third stage solenoid valve which will prevent flow from the  46 H-high pressure storage cylinder. In this way only compressed air/gas from the  44 H-low pressure storage cylinder is permitted to flow into the  55 H-SCBA cylinder being recharged. 
         [0068]    As the pressures between the  44 H-low pressure storage cylinder and the  55 H-SCBA being recharged begin to equalize, the flow of compressed air/gas passing through the  52 H and  53 H-flow indicating switches will slow or stop. The stoppage of flow through the  52 H-second stage and  53 H-third stage high pressure flow indicating switches will cause the electric current going to their respective  50 H-second stage solenoid valves and  51 H-third stage solenoid valves to be stopped thus enabling these two solenoid valves to revert to their normally open position. 
         [0069]    The opening of the second stage  50 H and third stage  51 H-electric over pneumatic solenoid valve re-establishes the compressed air/gas flow through the  58 -tubing. Since the pressure downstream of the  52 H-second stage flow indicating switch is greater than the upstream pressure, the  52 H-second stage flow indicating switch will convert to its secondary function as a check valve thus preventing pressure/flow from moving upstream from the  45 H-medium pressure storage cylinder into the  44 H-low pressure storage cylinder. This upstream to downstream pressure differential also aids in holding the  52 H-flow indicating switch in the “close” position which in turn will keep the second stage  50 H-electric over pneumatic solenoid valve in the “open” position. 
         [0070]    At the same time that the pressure/flow is being restricted from flowing upstream of  52 H-second stage flow indicating switch, the downstream pressure/flow begin pass through the  58 H-tubing and as it pass through the  53 H-third stage flow indicating switch will cause electrical current to be sent to the  51 H-third stage electric over pneumatic solenoid valve causing it to close thus permitting pressure/gas from only the  45 H-medium pressure storage cylinder entering the  58 -tubing and then subsequently flowing into the  55 H-SCBA cylinder being recharged. 
         [0071]    As the pressures near equalization between the  45 H-medium pressure storage cylinder and the  55 H-SCBA cylinder being recharging, the flow of air/gas will slow or stop. The stoppage of flow through the  53 H-third stage high pressure flow indicating switches will cause the electric current going to  51 H-third stage solenoid valves to be stopped thus enabling the  51 H-third stage solenoid valve to revert to its normally open position. 
         [0072]    The opening of the third stage  51 H-electric over pneumatic solenoid valve re-establishes the compressed air/gas flow through the  58 -tubing. Since the pressure downstream of the  52 H-second stage flow indicating switch and the  53 H-third stage flow indicating switch is greater than the upstream pressure, the  52 H-second stage flow indicating switch and the  53 H-third stage flow indicating switches converts to their secondary function as a check valve thus preventing pressure/flow from moving upstream into the  44 H-low pressure storage cylinder and the  45 H-medium pressure storage cylinders thus permitting pressure/gas from only the  46 H-high pressure storage cylinder entering the  58 -tubing and then subsequently flowing into the  55 H-SCBA cylinder being recharged. 
         [0073]    Note: While this demonstrates a 3-stage system, in actuality, this auto-cascade configuration can incorporate an infinite number of stages. Also, while this figure demonstrates the auto-cascade recharging a SCBA/SCUBA cylinder with compressed breathing air CGA grade “D”, “E”, and/or “L”, the auto-cascade in this design can be used with any type of compressed gas.