US3762304A

US3762304A - Valve responsive to air blast pressure or the like

Info

Publication number: US3762304A
Application number: US00191979A
Authority: US
Inventors: R Clark
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-10-26
Filing date: 1971-10-26
Publication date: 1973-10-02
Anticipated expiration: 1990-10-02

Abstract

An air flow valve responsive to air blast or shock wave pressure, including an air flow body divided into inlet and exhaust chambers by a deformable diaphragm. A plurality of parallel plates are spaced from the diaphragm onto which the diaphragm is deformed by the impacting shock wave. An enclosure is provided above the diaphragm extending to within the space between the parallel plates and diaphragm to receive air from the inlet chamber beneath the diaphragm through a plurality of interconnecting delay line tubes or plenums. Thus, air forced into the inlet chamber travels through the tubes into the enclosure, between the parallel plates to the space between the plates and the diaphragm, and then exhausted back through the parallel plates. Upon arrival of the shock wave, the diaphragm is deformed onto the plates and blocks the air path through the plates and, consequently, the exhaust chamber of the valve, before the arrival of the shock wave thereat.

Description

Oct. 2, 1973 United States Patent 1 Clark ABSTRACT VALVE RESPONSIVE TO AIR BLAST PRESSURE OR THE LIKE An air flow valve responsive to air blast or shock wave including an air flow body divided into inlet [76] Inventor: Robert 0. Clark, 5l8 Camino de la pressure Sierva N.E., Albuquerque, 87123 and exhaust chambers by a deformable diaphragm. A

plurality of parallel plates are spaced from the diaphragm onto which the diaphragm is deformed by the losure is provided above the diaphragm extending to within t Oct. 26, 1971 impacting shock wave. An cnc Filed:

he space between Appl. No.: 191,979

the parallel plates and diaphragm to receive air from the inlet chamber beneath the diaphragm through a plurality of interconnectin g delay line tubes or ple- [52] US. 98/ll9, l37/498, l37/5l7 [5H Int. Flblt 7/l7 nums. Thus, air forced into the inlet chamber travels through the tubes into the enclosure allel p between the par- [581' Field of Search............ ....,....t 98/] I); [37/517,

lates to the space between the plates and the diaand then exhausted back through the parallel phragm, plates. Upon arrival of the shock wave, the diaphragm I56] References Cited I UNITED STATES PATENTS is deformed onto the plates and blocks the air path through the plates and, consequently, the exhaust chamber of the valve, before the arriva 1 f th h k 137/5 wave thereat o e S QC 137/498 8 Claims, 5 Drawing Figures Mason Breckenridge..... ..t. Benz et Primary Examiner-William ODea Assistant Examinerl aul Devinsky Attorney-Richard A. Bachand PATENTED DU 2 973 SHEET 10F 2 Fig.|

INVENTOR.

Robert 0. Clark BY qxmgfgcm ATTORNEY PATENTEUUCT 2191a SHEET 2 BF 2 Fig. 2b

VALVE RESPONSIVE TO AIR BLAST PRESSURE OR THE LIKE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to improvements in air valves, and more particularly to improvements in valves operable in response to the throughflowing air pressure.

2. Description of the Prior Art It is often desirable to protect an area from, for example, oncoming air blasts or shocks, by such as one or more air overpressure actuated control valves or the like in the air intake flow path.

Such air valves are generally widely known and used especially in air ducts or air supply lines from above the surface of the ground to underground weapons systems or missle installations to shut off the air path in the event a shock or blast wave passes thereinto. The valves presently used are designed primarily under the assumption that high strength materials with massive movable closure mechanisms must be used to properly operate under such tremendous forces as may be encountered in high pressure air blasts. The closure mechanisms are, in fact, often so massive that considerable external force may be required to close the valve upon impact of a blast wave. Thus, ordinary air or blast valves generally employ some sort of hydraulic or other type mechanism to swing shut the heavy blast-closing doors of the valve and thereby aid the air overpressure in closing the valve. It may be seen, however, that a considerable time may be required to close such massive doors from the arrival time of the blast.

To prevent the shock from entering the protected area, a delay line or path is usually provided through which the shock is directed during the time the doors are closing. Most delay lines are extensive in length, for example, not uncommonly of two hundred feet or more, and, of course, a blast detecting system is also usually necessary to begin the doors closing upon arrival of the blast.

An additional problem arising from the extensive delay paths in their cleaning and maintenance. Since thermal, radioactive, and material debris which may be associated with a high pressure blast may flow into the delay paths, debris pits or chambers for capturing any such debris and material are sometimes included, further complicating the structure.

Thus, for a blast valve for merely closing an air duct or line, at least three fairly complicated support systems for the massive closing door structure are presently required, the auxiliary closure force producing means, the extensive delay path, and the debris chamber.

BRIEF DESCRIPTION OF THE INVENTION In light of the above, it is, therefore, an object of the invention to present a valve for controlling air flow.

It is a further object of the invention to provide a valve for controlling air overpressure which obviates using extensive delay paths.

It is'yet a further object of the invention to provide a valve for controlling air flow which does not require massive closure mechanisms and accompanying additional support systems or auxiliary closure force.

It is yet a further object of the invention to present an air flow valve which may be simply and economically fabricated.

These and other objects, features, and advantages will become apparent to those skilled in the art from the following detailed description, read in conjunction with the appended claims and accompanying drawing.

The air control valve, in accordance with the invention, in its broad aspect, includes a means defining an air flow chamber, the chamber being divided by an essentially flat diaphragm therewithin into first and second spaces. The diaphragm is made of a material which is permanently deformable by and in the direction of a shock wave of predetermined amplitude. Apluralityof parallel plates are also mounted within the second space, having concave edges adjacent the diaphragm, spacing the body of the plates from it. The plates provide an area between them through which air may flow, but onto which the diaphragm is deformedand retained by the impacting shock wave. At least one wall is provided within the second space extending to the concave edges of the parallel plates to divide the second space above the edges into third and fourth spaces, the third space being closed above the plates and the fourth communicating with the output of the valve. Finally, means are provided for carrying air between the first and third spaces. Thus, with the valveoperating as an inlet valve, air is forced into the first space which travels through the carrying means into the third space, then between the parallel plates to within the space between the edges of the plates and the diaphragm,.then back through the parallel plates intothe fourth space from where it is exhausted. Upon-the arival of a shock wave, the diaphragm is deformed against the concave edges of the platesthereby blocking the air path between the third and fourth spaces and cutting off the air flow through the valve.

BRIEF DESCRIPTION OF THE DRAWING The invention illustrated in the accompanying drawing wherein FIG. 1 is a cross-sectional plan view of an exemplary installation beneath the ground showing the valve incorporated thereinto, in accordance with the principles of the invention;

FIG. 2 is a perspective view of the valve of FIG. ll, partially cut awayto show the interior of the valve, in accordance with the invention;

FIG. 2a is a detailed perspective view of a modification of the valve of FIG. 2 showing a double diaphragm positioned beneath and adjacent the lower concave edges of the grid plates;

FIG. 2b ia s further enlarged detailed perspective view of the modification of FIG. 2a showing the top diaphragm partially cut away to clarify the position of the slots therethrough and to show the joining lines between the top diaphragm and the dividing walls within the exhaust chamber; and

FIG. 3 is a perspective view of an alternative preferred embodiment of the air control valve, in accordance with the principles of the invention, also partially cut away to show the interior structure of the valve.

It is understood that like reference numerals in the various figures of the drawing represent like parts. It should also be pointed out that various parts and features illustrated may be exaggerated in size or dimensions for clarity of illustration and ease of description.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In accordance with the invention, an air control valve is presented which may be used in underground missile or other such facilities to which air control is desired, particularly with a view to stopping air flow entirely after the onset of an air shock or blast shock. For example, as shown in FIG. I, the valve may be employed within an air flow line to a room 11 or other area beneath the ground 12.,A duct 13 may be provided to carry air from above the surface 14 of the ground to the intake 15 of the valve 10, and which may be pulled through the valve by a fan 16, or the like.

At this juncture it should be pointed out that a typical installation, such as room 11, will require both inlet and exhaust valves. Although the valve of the invention is described below with respect to its application as an inlet valve, its operation is precisely the same, except with reversed air flow direction, when used as an exhaust valve.

as shown in FIG. 2 the valve 10 is connected to the intake duct 13 through which air from the ground surface 14 flows. Extending upwardly from the intake duct 13 are a plurality of pipes 20, which serve to create a slight delay path for the incoming air, as described below in detail. Extending upwardly from the sides of the intake duct 13 are a plurality of upstanding pipes or ducts 21, attaching essentially tangentially to the intake duct 13. Thus, the intake duct 13 together with upstanding pipes 21, combined with enclosing end plates (not shown) form an enclosure or interior cham ber 22, having an open top 23, which may includes a number of connecting brace members or joists 24 in a grate-like pattern. The grate cross-members 24 serve to lend rigidity to the pipes 21, yet allow air to freely flow therebetween.

To conduct air through the pipes 21 are intake holes 25 and exhaust holes 26 at top and bottom portions of the pipes 21, respectively. Dividing the interior chamber 22 into first and

second air spaces

27 and 28, respectively, is a diaphragm 30, of metal, fiberglass, spring steel, rubber, or other such deformable material. If fabricated from metal, the diaphragm may conveniently be 0.125 inch thick spring steel or the like. The diaphragm 30 extends completely to the walls of the chamber 22, to essentially seal the bottom and

top spaces

27 and 28, respectively.

Above the diaphragm 30, in the second space 28, are a plurality of parallel plates 31, for example, of onefourth inch steel spaced one-fourth inch apart, to form a grid network which enables incoming air to flow therethrough in either direction. On the bottom edge of the plates 31 may be formed concave edges 32, to define an air space 33 between the plates and the diaphragm, thus spacing the diaphragm 30 from the plates.

Although as illustrated the parallel plates 31 have concave edges 32 spacing the diaphragm 30 from them, it should be understood that the plates may be one of manifold grid type configurations apparent to those skilled in the art, the primary consideration being to receive the diaphragm 30 in a manner to cut off the air flow through the valve 10. Likewise, the diaphragm 30 may be disposed flat within the valve 10, as shown, or may be arranged in a flexed position outwardly in the center away from the plates 31 such that it snaps into closed position upon impact of the air overpressure upon it; alternatively, the diaphragm 30 may be moved in its entirety to the plates or grid 31, perhaps from temporary rubber or the like holding devices (not shown).

Dividing the second air space 28 above the diaphragm 30 are

walls

40 and 41, extending from the top corners of the enclosure 22 to the bottom of the plates 31 at their concave edges 32. The exhaust space situated between the

walls

40 and 41 communicates upward with the opening in the top 23. Shock wave confining spaces are formed between the pipes 21 and

walls

40 and 41 respectively which are isolated from the opening in the top 23 except by way of the spaces between the plates 31. To make the areas between the dividing

walls

40 and 41 essentially air tight at the top, L shaped

members

42 and 43 are provided to which the

walls

40 and 41 may respectively seal. Thus, as shown by arrowed line 44, for an intake valve, air flowing into the valve 10 through intake duct 13, flows through pipes 20, and downwardly into intake holes 25 of pipes 21. The air is then directed upwardly through pipes 21 to be exhausted through holes 26 into the shock wave confining spaces between the

walls

40 and 41 and the pipes 21. The air then travels downwardly through the parallel plates 31 above the diaphragm 30, then within the space above the diaphragm 30 but under the concave edge 32 under the

walls

40 and 41. The air then travels upwardly between the plates 31 into the exhaust space between the

walls

40 and 41, and exhausts through the top 23 of the valve 10. Upon the arrival of a blast or shock wave the diaphragm 30 is deformed thereby upwardly against the concave portion of the plates 31, to effectively stop the air from traveling beneath the

walls

40 and 41, thereby shutting the valve off. In the event the valve 10 is used as an exhaust valve, the direction of normal air flow, represented by arrowed line 44, is reversed. The shock wave, however, enters the valve in the same manner through duct 13 against the outflowing air.

It can be seen, from the configuration of pipes 20, that the shock wave will directly impact upon the center of the diaphragm 30 to force it up onto the plates 31 to shut off the valve 10. Then, the shock wave continues to travel along the ordinary ventilation flow path through pipes 21 to impact downwardly against an outside edge of the diaphragm 30. The diaphragm, depending on a number of factors including the magnitude of the shock or blast, may not be reopened. It may, however, be necessary to include a double diaphragm, with the top diaphragm, 34 adjacent the grid of plates 31 as seen in FIG. 2(a), having a plurality of slots or holes 35, as best seen in FIG. 2b, passing downward through the two laterally separated portions of the diaphragm 34 extending inwardly from tubes 21 to

walls

40 and 41 respectively. The slots 35 are adapted to permit passage downward therethrough of the shock wave. Thus, if the shock is of such magnitude that the diaphragm would be moved back to its original position, only the bottom diaphragm 30 may be moved, the shock between the diaphragms actually reinforcing the closing seal. In that event the top diaphragm 34 would make contact with the bottom of

walls

40 and 41 along joining lines 36.

The various components of the valve 10 should be made of as heavy and durable material as practical. For example, the pipes 21 may be 4 inch outer diameter pipe with a wall thickness of approximately 0.250 inch,

and the upwardly extending pipes may be of 8 inch outer diameter with, also 0.250 inch walls.

Because of the particular spatial relationship of the air inlet pipes 20 beneath the diaphragm 30, a shock wave entering the valve 10 is partially reflected back out through the inlet duct 13, to set up a debris" barrier to later approaching shock waves. Since early arriving shocks are generally clean, or free from objectional debris, the valve does not pass any debris, hence requires no debris pits or the like.

An alternative embodiment of the invention is illustrated in FIG. 3. The valve 60 of FIG. 3, rather than being rectangular or square, as valve 10 of FIG. 2, is of cylindrical shape, consistent with many installation requirements. The valve 60 includes upstanding

parallel partitions

61 and 62 to define a slight delay path, together with additional parallel offset partitions 63 (the complementary partition to 63 not shown), to define a path or plenum between the intake chamber 64 and enclosed chamber 65 above the diaphragm 66. Additionally, extending across and between

partitions

61 and 62 are stiffener members 67. The diaphragm 66 and the parallel plates 70 having concave edges 68 facing the diaphragm 66 operate in the same manner as above described with respect to FIG. 2.

Extending downwardly from the dome-shaped top 75 are dividing wall members 76 and 77 to the concave edges 68 of the plates 70 to define, essentially, three chambers above the bottom of plates 70 through which air may ordinarily flow namely, an exhaust space between walls 76 and 77 and shock wave confining spaces between partitions 63 and walls 76 and 77 respectively, but which will enable the diaphragm 70 to cut off the air flow path after the oncoming shock has deformed the diaphragm 70 against the bottom of the plates 70 and the walls 76 and 77.

Thus, air flowing into the valve in opened position follows the path shown by arrow 80, up and around

walls

61 and 62, around wall 63 and its complement, not shown, beyond wall 62, through plates 70, to the space between the diaphragm 66 and the concave edges 68 of the plates 70. It thenflows beneath the walls 76 and 77, back through the parallel plates '70 and is into the central exhaust space formed by dividing walls.76 and 77 exhausted out through the top of the valve 60. V

Although the invention has been described and illustrated with certain degree of particularity, it is .understood that the present disclosure has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the scope and spirit of the invention is hereinafter claimed.-

1 claim: 1. A valve positionable in an airflow line for controlling air over pressure in said airflow line, comprising: a. a hollow airflow body having a bottom, a top, and

side walls; v

b. a diaphragm extending laterally between said side walls intermediate said bottom and top to divide said airflow body into an inlet chamber and an exhaust chamber communicating through openings in said bottom and said top respectively with the airflow line, said diaphragm being displaceable by and in the direction of travel of an impacting wave of air over pressure in said airflow line;

c. a diaphragm receiving grid within the exhaust chamber spaced above said diaphragm and onto which said diaphragm is displaced by the impacting wave;

d. means within said exhaust chamber extending downward to the bottom of the grid for dividing the exhaust chamber there-above into an exhaust space communicating upward with the opening in said top and a shock wave confining space isolated from said opening in said top except by way of said grid; and

e. means bypassing said diaphragm for transmitting a delayed wave of said air over pressure from said inlet chamber into said shock wave confining space within said exhaust chamber, whereby upon introduction of the wave of air over pressure into the inlet chamber through the opening in said bottom said diaphragm is displaced onto said grid thereby blocking the air path between said shock wave confining space and said exhaust space, cutting off the valve.

2. A valve positionable in an airflow line for controlling air over pressure in said airflow line, comprising:

a. a hollow airflow body having a bottom, a top, and side walls; i

b. a diaphragm extending laterally between such side walls intermediate said bottom and top to divide said airflow body into an inlet chamber and an exhaust chamber communicating through openings in said bottom and said top respectively with the airflow line, said diaphragm being displaceable by and in the direction of travel of an impacting wave of air over pressure and said airflow line;

c. an intake duct in said airflow line communicating with said inlet chamber through the opening in the bottom thereof to transmit a wave of air over pressure therein;

(1. a diaphragm receiving grid within the exhaust chamber spaced above said diaphragm and onto which said diaphragm is displaced by the impacting wave;

e. means within said exhaust chamber extending downward to the bottom of the grid fordividing the exhaust chamber there-above into an exhaust space communicating upward with the opening in said top and a shock wave confining space isolated from said opening in said top except by way of said grid; and

f. a plurality of upstanding adjacent parallel pipes extending between said inlet and shock wave confining space externally of said diaphragm, each pipe having a first hole communicating with the inlet chamber near said intake duct and a second hole communicating with the shock wave confining space in said exhaust chamber to provide a bypass around said diaphragm adapted to transmit a delayed wave of said air over pressure between said inlet chamber and said shock wave confining space.

3. The valve of claim 2 further comprising a second plurality of upstanding pipes within said inlet chamber communicating with said intake duct, opening onto said diaphragm to direct the over pressure wave onto said diaphragm and to define an airflow delay path with respect to the first holes of said plurality of adjacent parallel pipes.

5. The valve of claim 2 whwerein said diaphragm is spring steel of thickness of approximately 0.125 inches.

6. The valve of claim 2 further comprising a second diaphragm positioned between said diaphragm and said grid and displaceable with said grid, said second diaphragm being provided onto a plurality of slots passing vertically therethrough and spaced so that they do not communicate with said exhaust space upon displacement of said second diaphragm onto said grid.

7. A valve for cutting off an airflow path in response to air over pressure comprising:

a. a walled enclosure having a top and a bottom;

b. a first pair of upstanding partitions extending through the bottom to within said enclosure to form an inlet path communicating between the interior and exterior of said enclosure;

0. a second pair of upstanding partitions between said first partitions and the walls of said walled enclosure and extending above the top of said first pair of partitions to almost the top of the enclosure and below the top of said first pair of partitions to almost the bottom of the enclosure to define a delay path within said walled enclosure;

d. a laterally extending diaphragm connected between said second pair of upstanding partitions immediately above said first pair of partitions, said diaphragm dividing the interior of the enclosure into a lower inlet chamber and an upper exhaust chamher, said diaphragm being displaceable by and in the direction of travel of the air over pressure entering the inlet chamber along said intake path;

e. a grid carried between said second pair of upstanding partitions above said diaphragm onto which said diaphragm is displaced by the air over pressure; and v a pair of dividing walls connected to said top and extending downward therefrom within said exhaust chamber inward of the second pair of upstanding partitions to the bottom of said grid to divide the exhaust chamber there-above into an exhaust space communicating upwardly with the outlet of said valve through said top and a shock wave confining space isolated from said top except by way of said grid, whereby upon introduction of the wave of air over pressure into the inlet chamber along said intake path the diaphragm is displaced on said grid to block the airflow path between said shock wave confining space and said exhaust space.

8. A valve for cutting off an airflow path in response to air over pressure comprising:

(a) a walled enclosure having a top and a bottom;

(b) a first pair of upstanding partitions extending through the bottom to within said enclosure to form an intake path communicating between the interior and exterior of said enclosure;

c. a second pair of upstanding partitions between said first partitions and the walls of said walled enclosure and extending above the top of said first pair of partitions to almost the top of the enclosure and below the top of said first pair of partitions to almost the bottom of the enclosure to define a delay path within said walled enclosure;

d. a laterally extending diaphragm connected between said second pair of upstanding partitions immediately above said first pair of partitions, said diaphragm dividing the interior of the enclosure into a lower inlet chamber and an upper exhaust chamher, said diaphragm being displaceable by and in the direction of travel of the air over pressure entering the intake chamber along said intake path;

e. a plurality of parallel plates within said exhaust chamber extending at right angles to said diaphragm and spaced apart therefrom, said plates having bottom edges with concave contours adapted to receive and retain said diaphragm upon displacement thereof; and

f. a pair of dividing walls connected to said top and extending downward therefrom within said exhaust chamber inward of the second pair of upstanding walls to the bottom edges of said parallel plates, thereby dividing the exhaust chamber there-above into an exhaust space communicating upwardly with the outlet of said valve through said top and a shock wave confining space isolated from said top except through said parallel plates, whereby upon introduction of the wave of air over pressure into the inlet chamber along said intake path said diaphragm is displaced onto said parallel plates to block the airflow path between said shock wave confining space and said exhaust space.

Claims

1. A valve positionable in an airflow line for controlling air over pressure in said airflow line, comprising: a. a hollow airflow body having a bottom, a top, and side walls; b. a diaphragm extending laterally between said side walls intermediate said bottom and top to divide said airflow body into an inlet chamber and an exhaust chamber communicating through openings in said bottom and said top respectively with the airflow line, said diaphragm being displaceable by and in the direction of travel of an impacting wave of air over pressure in said airflow line; c. a diaphragm receiving grid within the exhaust chamber spaced above said diaphragm and onto which said diaphragm is displaced by the impacting wave; d. means within said exhaust chamber extending downward to the bottom of the grid for dividing the exhaust chamber there-above into an exhaust space communicating upward with the opening in said top and a shock wave confining space isolated from said opening in said top except by way of said grid; and e. means bypassing said diaphragm for transmitting a delayed wave of said air over pressure from said inlet chamber into said shock wave confining space within said exhaust chamber, whereby upon introduction of the wave of air over pressure into the inlet chamber through the opening in said bottom said diaphragm is displaced onto said grid thereby blocking the air path between said shock wave confining space and said exhaust space, cutting off the valve.

2. A valve positionable in an airflow line for controlling air over pressure in said airflow line, comprising: a. a hollow airflow body having a bottom, a top, and side walls; b. a diaphragm extending laterally between such side walls intermediate said bottom and top to divide said airflow body into an inlet chamber and an exhaust chamber communicating through openings in said bottom and said top respectively with the airflow line, said diaphragm being displaceable by and in the direction of travel of an impacting wave of air over pressure and said airflow line; c. an intake duct in said airflow line communicating with said inlet chamber through the opening in the bottom thereof to transmit a wave of air over pressure therein; d. a diaphragm receiving grid within the exhaust chamber spaced above said diaphragm and onto which said diaphragm is displaced by the impaCting wave; e. means within said exhaust chamber extending downward to the bottom of the grid for dividing the exhaust chamber there-above into an exhaust space communicating upward with the opening in said top and a shock wave confining space isolated from said opening in said top except by way of said grid; and f. a plurality of upstanding adjacent parallel pipes extending between said inlet and shock wave confining space externally of said diaphragm, each pipe having a first hole communicating with the inlet chamber near said intake duct and a second hole communicating with the shock wave confining space in said exhaust chamber to provide a bypass around said diaphragm adapted to transmit a delayed wave of said air over pressure between said inlet chamber and said shock wave confining space.

4. The valve of claim 2 wherein said grid comprises a plurality of parallel plates extending at right angles to the diaphragm, the bottom edges of said plates having a concave contour adapted to receive and retain said diaphragm upon displacement thereof.

7. A valve for cutting off an airflow path in response to air over pressure comprising: a. a walled enclosure having a top and a bottom; b. a first pair of upstanding partitions extending through the bottom to within said enclosure to form an inlet path communicating between the interior and exterior of said enclosure; c. a second pair of upstanding partitions between said first partitions and the walls of said walled enclosure and extending above the top of said first pair of partitions to almost the top of the enclosure and below the top of said first pair of partitions to almost the bottom of the enclosure to define a delay path within said walled enclosure; d. a laterally extending diaphragm connected between said second pair of upstanding partitions immediately above said first pair of partitions, said diaphragm dividing the interior of the enclosure into a lower inlet chamber and an upper exhaust chamber, said diaphragm being displaceable by and in the direction of travel of the air over pressure entering the inlet chamber along said intake path; e. a grid carried between said second pair of upstanding partitions above said diaphragm onto which said diaphragm is displaced by the air over pressure; and f. a pair of dividing walls connected to said top and extending downward therefrom within said exhaust chamber inward of the second pair of upstanding partitions to the bottom of said grid to divide the exhaust chamber there-above into an exhaust space communicating upwardly with the outlet of said valve through said top and a shock wave confining space isolated from said top except by way of said grid, whereby upon introduction of the wave of air over pressure into the inlet chamber along said intake path the diaphragm is displaced on said grid to block the airflow path between said shock wave confining space and said exhaust space.

8. A valve for cutting off an airflow path in response to air over pressure comprising: (a) a walled enclosure having a top and a bottom; (b) a first pair of upstanding partitions extending through the bottom to within said enclosurE to form an intake path communicating between the interior and exterior of said enclosure; c. a second pair of upstanding partitions between said first partitions and the walls of said walled enclosure and extending above the top of said first pair of partitions to almost the top of the enclosure and below the top of said first pair of partitions to almost the bottom of the enclosure to define a delay path within said walled enclosure; d. a laterally extending diaphragm connected between said second pair of upstanding partitions immediately above said first pair of partitions, said diaphragm dividing the interior of the enclosure into a lower inlet chamber and an upper exhaust chamber, said diaphragm being displaceable by and in the direction of travel of the air over pressure entering the intake chamber along said intake path; e. a plurality of parallel plates within said exhaust chamber extending at right angles to said diaphragm and spaced apart therefrom, said plates having bottom edges with concave contours adapted to receive and retain said diaphragm upon displacement thereof; and f. a pair of dividing walls connected to said top and extending downward therefrom within said exhaust chamber inward of the second pair of upstanding walls to the bottom edges of said parallel plates, thereby dividing the exhaust chamber there-above into an exhaust space communicating upwardly with the outlet of said valve through said top and a shock wave confining space isolated from said top except through said parallel plates, whereby upon introduction of the wave of air over pressure into the inlet chamber along said intake path said diaphragm is displaced onto said parallel plates to block the airflow path between said shock wave confining space and said exhaust space.