US1617691A - System of lightning protection - Google Patents

Description

Fv 1 1 eb 5 927 E. c. VAN DlEs-r ET AL SYTE14 O LIGHTNING PROTECTION Filed Aug. `6, 1921 Patented F eb. 15, 1927.

UNITED `STATES PATENT oFFicE.

EDMOND C. VAN DIEST AND FRANCIS GILPIN, OF COLORADOv SPIINGS, COLORADO- SYSTEM OF LIGHTNING PROTECTION.

Application filed August 6, 1921. Serial No. 490,275.

` This invention relates toa method and apparatus for the protection ot' buildings, vtanks and other structures against lightning,.and its primary object: is to provide a protective medium ol siuple and highly etliciciit construction which il' properly applied to ataiik or other elevated structure will, duril'ig electrical storms, prevent the formation of flashes, coi'uiiioiily. known'as lightning, in the. region over the protected area and thereby prevent the destruction of life and property.

We attain this object by causing a dllusion of the ground currents induced during electrical storms-through the .medium of a .multitude of points of discharge above the protective area which'prevent the concentration of electricity necessary to produce a disruptive lightning discharge.

It is Well known that the lightning flashes wh' h are most destructive to life and propert are those lcaused by a s dden discharge of electricity between anelectriticd cloud and the earth. The cloud is composed of finely divided particles ofvapor, each particle-'a'ctingas av carrier of the electric en-A A.ergy latent in the atmosphere and when the vapor becomes sufficiently dense it is precipi.

tated as rain and the electric energy carried by the vapor particles becomes concentrated and induces a similar concentration of electricity of opposite polarity on the surface of the earth.

vThe discharge between these forces when so' concentrated as to disrupt the intery'vening medium causes the lflash or bolt of lightning which by fire alone destroys, an-

' nually, property to an aggregate of millions of dollars. .i

The lightning flashes occurring during electric storms are thus directly'caused by the concentration of induced ground currents, most frequently in elevated objects such asa knoll, tower, building, tank or tree, while the electric current in the cloud is diffusedy by distribution through the countless particles of moisture of which it is composed and it will be evident that if the induced-"ground current yis prevented from concentrating by4 immediate diffusion, no flash o'flightning canxoccur.

It is upon this principle that our invention is based and it is carriedl into effect by coveringl the area to be protected by a multitude ol' iiitercoiiiiiiunicaling upright points which either singly or collectively are connected with the ground. 'l'lic iiuiiiliei' of ipoints required to fully protect the huilddiuin of a common metallic conductor of electricity since by these means a collector of induced current is provided on all sides of the protected structure, which will most directly cause itsdiffusion through the instrumentality of the electrically connected points.

While we do not desire to limit ourselves to the use of any specific mechanicaldevice for carrying our improved method of lightning prevention into practice, we preferably employas a conductive supporting medium for the ramifying points, a metallic ribbon which with' a minimum of material provides a large conductive surface-area and a degree of flexibility which greatly facilitates its application to structures of different forms and dimensions.

In order to fully protect a structure of extensive area, the ribbons may be interconnected in a net work which covers the surface and is connected with the ground at different sides thereof and since it is essential that the points extend in a substantially upright position, We have provided a simsential :if the material of the structure has a lesser degree of conductivity, `and when the surface to which the net f work `of point carrying conductors is applied, slopes to an apex, the points are preferably spaced closer together as they approach the highest point, since it is well known that the induced ground currents tend to concentrate at thc inost elevated portion of an object.

An embodiment of our invention has been illustrated in the'acconipanyi'ng drawings in the various views of which like parts are nfragmentary plan view of the device to prevent ignition of its contents by accidental sparks;

Figure 4, a vertical section through an oil tank, illustrating a -mo fification` in the method of applying our invention thereto;

Figure 5, an enlarged sectional elevation of one of the current diusing points and the conductive support thereof;

Figure 6, a fragmentary section along the line 6-6, Figure 5, and

Figure 7 a fragmentary enlarged view of one of the ribbons-showing the spacing of the points thereon.

Referring to the drawin s, the reference character 5 designates a ta of a type used for the stora e of oils or other inflammable liquids, Whici is supported in an upright position on a suitable foundation and'whoh is covered by a relativelyat and conical roof.

The protective system of ourinvention comprises a number of ribbon shaped conductoi's 3 which radiate from a central hub plate 7. The net work is arranged to adequately cover the roof of the tank and its radiating members are bent downwardly at the peripheral edge of the saine to extend along the upright surface of the structure for their connection with the ground.

The points 8 which extend vertically from the portions of the conductor on the roof of thetank are spaced progressivelfurther.

apart as they near the eripheral e ge thereof, as best shown in igure 7, and they are erected upon the conductors through the medium of sockets 6 which are fastened there.-

to b solderor other suitablel expedient.

T ie openin of the sockets are elongated to permit of t e adjustment of the points to an upright position should the surface on which the ribbon restsbe out of the horizontal, and the points are secured in the sockets by solder inserted into the cavities thereof.

The points consist of short metallic rods providedwith a sharptapering end and the ground connection between the downwardly extending portions ofthe point-supporting i thereby v electrified clou rial, but it will be understood that in caseA Vthe structure to which the system is applied is a poor' conductor of electricity, these Lnsul'ations may be omitted. f

In this connection it will be observed that under certain advantageous conditions, the ribbons may be entirely omitted and the points applied directly to the roof of the metallic structure, as illustrated in Figure 4 of the drawings.

It will be apparent that in the event of an electrical storm the induced ground current is diffused by the multitude of electi'ically intercommunicating and ground-connected points and that the concentration necessary to produce a Hash of lightning is prevented. It follows that where the points are a plied in suicient quantities to oiset the e ectric conductivity of the structure with a fair degree of' safety, no

.of e ectrical storms by preventing any disruptive dischar e o electricity between the dg and the earth.

In Figure 3 of the drawin s is shown an auxiliary device to prevent t e contents of a tank to which our invention is applied from catching fire by sparks which might acci-- dentally be thrown off from the points or conductors during electrical storms.

The device consists of a chamber 13 formed above the roof of the tank by an extension of the circumferential wall thereof, and a second roof which is spaced from the other. The chamber has in the center of its roof an opening covered with a fine mesh screen 14 and similarly covered olpenings 15 maIy be formed in its upright wal .nl'lammable gases arising from the combustible contents of the tank and escaping through leaky rivet holes or other apertures caused by imperfect joints between the parts of which the structure is composed, are upon entering the chamber, artially dissipated through the openings in its sides, but Vthe greater portion of the gases escapes through the meshes of the screen which covers the opening in the roof.

In the event of a spark being thrown off any of the points of the protective medium which in this case is placed to cover the roof of the chamber, the possible ignition of the gases will occur above the' screen 14 and are there consumed. The screen thus acts as a burner' for the gases arising from the chamber and the flames are prevented from reaching the contents ot' the tank in any manner whatsoever.

The chamber thus provides a protective medium Whichivill effectively prevent cpntlagrations such as frequently occur by lightning or other causes, and we desire it understood that it' so'desired the chamber may be used without the current dii'using element within the scope ot' our invention.

lVhen the tank is used without-the superposed chamber, the screen-covered opening can be formed directly in the root thereof, to concentrate accumulated gases to one foraminated outlet which as before, acts as a burner for their consumption outside the tank in case of lire.

The outlet whether in the roof of the tank or in the ro'of of the chamber is obviously placed so as not to be obstructed by the conductivesupports of the lightningprotector outlet r outlets in the roof of the tank isA similar to those of the outlet or outlets in the roof of the chamber, as shown in Figure 3, no separate illustration'of this feature of the invention is required to convey a complete understanding o its purpose and advantages.

What We claim and desire to secure by Letters-Patent is:

1. In a system for protecting structures from lightning, a plurality of conductive radial arms, and vertically disposed conductive pointsprotruding 'from the upper surface of each of said radial arms, thc said points being arranged in continuous rows and spaced in such manner that the distance between the successive points of each row' decreases as the center is approached.

2. A. system for protecting structures from lightning, comprising a central inember, a plurality of conductive radial arms disposed about said central member, and vertically disposed conductive points protruding from the upper surface of said central member and of each of said radial arms, the. said points being arranged in continuous rows and spaced in such manner that the distance between the successive points ot' each row decreases as the center is approached.

3. A. system for protecting structures from lightning, comprising a central hub plate, a plurality of conductive radial arms disposed about said hub plate, uprights integral with said radial arms, the lower ends of which are adapted to be grounded, a common metalliclv strip engaging said lower ends, and vertically disposed conductive points protruding from the upper surface of each of. said radial arms,-the said points beingV arranged in continuous rows and spaced in such manner that the distance between the successive points of each row decreases as the center is approached.

In testimony whereof we have aixed ourv signatures.

EDMOND C. VAN DIEST. FRANCIS GILPIN.

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