US2049987A - Method of and means for protecting combustibles - Google Patents

Description

Aug. 4 1936. w. J. WILLENBORG METHOD OF AND MEANS FOR PROTECTING COMBUSTIBLES Filed Jan. 15, 1950 3Sheets-Sheet, 1

I um/n h d/fer f hW/mfioy Aug. 4, 1936. I w. J. WILLENBORG 2,049,987

METHOD OF MEANS-FOR PROTECTING CQMBUSTIBLES Filed Jan. 13, 1950 :s Sheets-Sheet? awuwtoz ll d/ /ir i v [VJ/c0507 936. w. J. 'WlLLENBORG 2,049,987

' METHOD OF AND MEANS FOR PROTECTING COMBUSTIBLES. I

' 'Fild Jan. 13, 1950 s Shets-Sheet :5-

anoemtoz ,Patented Aug. 4, 1936 rras . ms'rnon or" arm man's ron PRO- rncriuc coMBUs'rmLEs Walterii. Wilienborg, Weehawken, N. 5., assignor to United States Fire Protection Corporation, l-ioboken, N. J., a corporation of Delaware Application January 13, 1930, Serial No. 420,613

15 Claims. (01'. 230-85) mable gases;' it is the object of this invention to provide protective means for the spaces ,in which combustibles are kept.

An important object of my invention is to provide and maintain, in spaces in which combustibles are kept, an atmosphere in which such combustibles, or gases given off thereby, cannot be infiarned or burned.

Another object is to devise means by which the so-called inert atmosphere in .spaces which serve for the storage of combustibles is kept substantially at atmospheric pressure, so that the walls of said spaces are not exposed to excessive strains. Giving to the walls of such spaces sufficientstrength to withstand the pressure of the atmoshere on the outside, in case the atmosphere in said spaces is rarefied, or to withstandan excessive pressure of the "inert gases-contained therein, would represent a considerable economical burden, particularly because such spaces are frequently very large.

1 Another important reason for preserving the inert" atmosphere in such spaces at a pressure substantially equal to that of the atmosphere surrounding said spaces is the object of preventing the leakage of the inert gases contained therein through cracks or openings 'in the walls making up said spaces, or, to prevent the difiusion of the outside air through such cracks-or openings into the inert atmosphere which is maintained on the inside .of such spaces.

A further object of this invention is to maintain the inert atmosphere in a space, in which combustibles are contained, at a standard of safety which experience has proven to oflera fully satisfactory protection and automatically to raise said standard of safety in case the requirements of protection are increased, when inflammable gases are given off by the combustibles in said space.

It is another object of my invention to provide compensation for the fluctuation of the amount of inert gases contained at substantially atmospheric pressure in such spaces, such I fluctuation being caused by an increase or de-' must frequently be accorded to the spaces where such means and machinery are operated, be-

cause mechanical friction and electric sparks, which are difficult to avoid in the operation of such means and machinery, must be protected against, in order to prevent, ignition and explosion of the surrounding atmosphere. I have devised regulation for the atmosphere in the spaces in which such means and machinery are kept, which affords a protection against such ignition or explosion and which'at the same time permits the entrance of a person into the respective spaces for the purpose of manually opcrating such means or machinery in the case of an emergency.

Another, important object of my invention is to provide for the protection of the inside of the. tanks of a tanker, which are known to corrode and deteriorate at an extraordinary rate under the combined and alternating influences of salt water, air, oil and oil-vapors. -Such de-- terioration is effectively prevented by my invention in which the atmosphere in the tanks is largely rendered inert.

In view of these and other objects I have developed the method and means described below, and; have exemplarily chosen for an illustration of my invention a prominent field of its application, which is tankers used for the overseatransportation of inflammable liquids, such as oil, petroleum or gasoline. Such tankers and the means whichI use in the application of my protection to such tankers are illustrated in the accompanying drawings, in which,-

Figure .1 is a side elevation of part of a tanker.

Figure 2 is a corresponding plan view of the tanker.

Figure 3 shows a schematic top view of the arrangement of pipes, pump and control means in the shaft.

Figure 4 is a corresponding part of the "shaft.

Figure 5 is the side elevation of the forepart of a vessel showing a modification of my invention.

Figure 6 shows a diagram view of the vapor indicator and the apparatus controlled thereby.

Figure 7 shows a partly sectioned side View of the breathing means. Similar numerals refer to similar parts throughout the various views.

, The tanker shown in Figures 1 and 2 is laid along the lines of present day practice of constructing vessels of this type. The engine andboiler rooms are arranged in the stern of thevessel and the power plant comprises a generator which supplies steam or electricity for the opera-- side elevation of tion of the motive parts, primarily pumps, used in connection with my improvements; the bow is used for freight, and quarters for the crew whereas the tanks containing the liquid cargo are arranged therebetween and are ordinarily separated from the fore and aft parts of the vessel by protective coffers. Two vertical shafts I3 and M, which are normally open at their upper ends extend down from the main deck to substantially the keel; in their lower ends I5 are arranged the oil pumps which serve to pump the oil out of the vessel. Two pairs of main tanks l6 and I1 are arranged aft each of the shafts I3 and I4 and correspondingly two pairs of tanks I8 and I9 are arranged fore thereof.- Alongside of the tanks I0, II, I8 and I9 are indicated the wing tanks I0 which may be protected by my improvements in a manner corresponding to the hereinafter described protection of the first-mentioned tanks.

The various tanks are ordinarily filled with oil or gasoline.l2, a small clearance being allowed between the surface of the liquid and the top walls of said tanks, which are represented by the main deck. These clearances allow for. the expansion and contraction of the liquid under dif-- :in the tanks above the liquid, if the tanks were hermetically sealed, and the walls of the-tanks would thereby be exposed to dangerously high and low pressures. For this reason so-called breathers are ordinarily provided, which, througha trap-like arrangement, connect the gas filled space above the liquid in the tank to the outside and through which the pressures above the liquids phere.

in the tanks may be balanced against the atmos- Through such breathers air is taken in when, at sunset, the contracting contents of the tanks tend to create a vacuum thereabove; whereas gas is driven out through the breathers, when the temperature rises in the morning.

-In my invention the unidirectional valves 20 take the place of the breathers. They permit the excess pressure of gas above the liquid in the tanks to be relieved therethrough, but they do not allow air from the outside to enter into the space above the tanks at night, when the temperature drops and a vacuum is created above the liquid, but I provide in that case other means for restoring the low gas pressure above the liquid to a normal pressure, which is slightly above atmospheric pressure. v

The unidirectional valves maybe constructed according to the simple principles of a safety valve; they may take the shapes of traps, the liquid in which allows the passage of gas therethrough in one but not in the other direction or they may take the shape of one of the many devices which provides for unidirectional sensitive gas pressure control. To the unidirectional valves are connected the pipe lines 2| extending to the sides of the ship and their outlets 22 issue overboard, below the'level of the main deck.

A detailed illustration of a particular modification of the breathing apparatus is shown in'Figto those acquainted with the art of valve sears.

I sea.

The checking operationin the. valve body is brought about by the plunger IOI which operatively connects a diaphragmin the diaphragm chamber I02 to the shut off means in the valve body proper. The valve connects by means of the pipe I03 to the space above the liquid in the tanker and an auxiliary. pipe I04 by-passes a small amount of the gas coming from the tank into the diaphragm chamber. In the diaphragm chamber the diaphragm is raised and lowered I06 and a screen I01 which extends across the whole horizontal extent of said chamber I06. Flash-arresters of this kind are used in the line through which, surplus gas is released from the pump room, as well as throughout the apparatus of my invention wherever pipe lines issuing from one or the other tank are merged or are connected to a common header. If for any unforeseeable reason an inflammable gas mixture is contained in one or more of the tanks, such flash-arresters prevent the propagation. of .an explosion, which may occur in one of said tanks, to the other tanks. Below the flash-arrester, above the outlet of the breatherv line, thepipe shows another enlarged chamber-I00 in which a hollow ball I09 is supported, from-below, by brackets IIO. Chamber I08 is of such size as to allow a free passage of the gases breathed out from the tanks around said ball. I09. The contracted lower end of the pipe prevents splashing .of water thereinto and the ball I09 is buoyed and blocks the neck III of chamber I00, when'the lower end of the breather pipe line is submerged under water in a rough 7 Near the center of thebody arises above the main deck an inert gas Igenerating plant 23 in which, by means of an internal combustion engine 24, gases are produced which are commonly termed ine gases. These inert gases are the exhaust gases of the engine 24 and are termed inert" gases because they are non-oxidizing, inasmuch as they prevent the combustion of inflammable materials therein, unless such inflammable materials contain the oxygen required for their combustion. The exhaust gases of the engines 24 are purified and cleaned in scrubbers 25 and then they are stored in high pressure tanks 20. These high pressure tanks are connected by pipe lines 28 to a reducing valve board 21 from where pipe lines 29 connect into the shafts l3 and I4. The reducing valves are set to maintain the gas in pipe lines 20 at a pressure which assures a free flow of said gases to the points of use of such gas, when required. The gas for the operation of engines 24 is supplied from an auxiliary gasoline. tank 30. This gasoline tank and the pipe line 3| connecting said tank to the engines are protected and jacketed with inert gas manings sealed by heavy glass covers 33. These pump rooms are filled with an inert atmosphere, means for maintaining such an atmosphere being more specifically discussed below. At times, when it becomes necessary to enter this chamber, air 7 is admitted, so that the breathing of a person entering the pump. room is not impaired; at the same time an explosion-proof condition of the atmosphere in the pump room may be maintained. it being known that the-oxygen in a room may be reduced to such an extent, that it will not permit ignition of inflammable materials, said atmosphere not causing to a person entering thereinto any serious discomfort excepts slight shortness of breath.

On deck 32 in the pump room I install the apparatus by which I protect the inflammable-liquids contained in the various tanks I6, II, It and i0.

' The equipment in each of the shafts i3 and I4,

into lines at and 55 which issue into the respecr I tive pairs oi port and starboard tanks below the main deck and above the top level of the liquid. 4 The suction lines 38, 31, 08, 49 and 50 connect, as return lines, the tanks 10, II, It and i9 and the pump'rooms E5 to the blowers 34, 05, 30, 31 and 38. .In the manner of the branches 44 and 40 issuing from the discharge lines 38,-40, 4|, and 62 into the various tanks l8, l1, l8 and [9, the

suction lines 66, $1, $8 and 49 are branched oil at their ends by lines 5| and'52.- The pipe, lines El and '52 issue upon the opposite ends of the spaces above the liquids in each of the port and starboard tanks. I

The discharge lines are provided with check valves 53 at points near the blowers and, ahead of these valves, small pipe lines 50 branch oi! and lead to the vapor indicators 05. Behind the check valves the pipe lines 56 issue thereinto. Those pipe lines 56 connect to the solenoidal valves 51 which in turn connect to a manifold 58 to which 13 and i i.

inert gas reduced to a predetermined pressure is supplied from the reducingvalve boa-rd 2'! of the inert" gas generating plant by pipe line 29. The solenoidal valves connect to the manifold M by the pipe lines 59, 80, 6t, 62 and, 63, which, respectively, belong to the systems of the blowers '38,

M, 31, 36 and 3b.

The operation of the vapor indicators and of the solenoidal valves may best be seen from the diagram of Figure 6; an unbalanced Wheatstone bridge M is connected by means of wires 65 and 66. across the source 67- of a' constant E. M. E. One pair of arms of the bridge are formed by-the fixed resistances 6t and 69, whereas the other pair of arms contain the resistance wires of-the thermal conductivity units I0 and .H. The gal-- vanometer F2 is connected across the bridge as an indicating instrument by'means of the wires Thermal conductivity unit I0 is bridged by a suitable resistance wire and it contains a comparison gas, whereas the thermal conductivity unit H which is equipped with a similar resistance wire is connected at the inlet 15 to the small pipe line 54 through which gas is supplied for analysis from the blowers.

, The galvanometer is empirically calibrated, I

showing a-scale fromzeroto 100 which may be defined as a percentage scale for inertness of the gas analyzed. The divisions are arra ged in such a manner that a-de-flection of 50 is registered by the galvanometer when air mixed with just enough inert gas so as not to sustain free combustion passes through the conductivity unit H, whereas the 100% point of the scale is registered, when the'best possible "inert" gas produced by the generating plant 23 is introduced in the thermal conductivity unit ll.

Exemplarily I choose thecalibration point 50' of the-scale for the quality which is to be main- I tained in the gas above the liquid. in the tanks.

. I exemplarily allow 15% upward and downward marginal limits for that standard; therefore I l0 have provided means that a supplyof substantially. fully inert" gas which has been delivered by the generating plant is admitted through the pipe line 56 into the discharge of the blower,

when theinertness indicator registers per- 15 cent but I shut oil this supply of inert gas when the inertness" is indicated to have risen to 65%. Simple means to bring about such a control of thesupply of inert gas by means of thevapor indicator are shown in Figure 6; the hand I6 of the 20 galvanometer 12 carries a brush 11 near its point-- ed end which is adapted to contact electrically with the segments 18 and 19, when either an inertness .from zero to 35% or from 65% to 100% is registered. Electricity is supplied to the 20 hand by means of wire 80 and it flows from the galvanometer through wires BI and 82 to relays 03 and, when the brush 11 on hand 16 contacts with the segments l8 and |9 respectively. A return wire 85 closes the electric circuit and it also supplies electricity to the magnet lever 86, which will swing to the right or to the left according to whether relay 03 or relay M is excited.

Whereas the various pieces of electrical apparatus are shown to be supplied with current from 35 a common source ti, they may of course be supplied from difierent sources of current, each one oi'which is particularly suited for the respective current requirements; or the various electrical devices such as the analysis units, the solenoidal valves, the relays, and the apparatus used collaterally in the galvanometer operation may be floated on the line oi'the ship's electrical power supply.

The diagrammatic drawing of Figure 6 illus-- trates the principle upon which the vapor indicator controls the -inert gas supply. In a practical application the hand 18 oithe galvanometer is of course not used for carrying currents, nor do which I may choose the one best. adapted for the problems of a particular installation. The circuit closing contact does not have to be brought about directly by the handf'lt, but the present state of the art ofiers'many instniments in which such a contact is indirectly brought about and instruments in which periodically, at short and regular intervals ai time, mechanical means automatically feel ,out or test theposition of a pointer and accordingly close or open relay circuits. and which may readily be substituted for the apparatus diagrammatically shown in the drawings. I U I The lever 06 is, retained in its positions o1' at'- traction to one or theother oi the relays by the wedge-shaped nose extending from an upwardly tensioned catch 81, said wedge-shaped nose engaging the right or left side of the lower pointed end of the lever 86 in the extreme positions of deflection of said lever. When the lever 86 is attracted by relay 06, it closes the circuit .94 of the solenoidai valve 51 at the pointof contact 88,

which circuit inthe drawing is connected across the source .61 of electric power. The solenoidal valve 51 is normally open, so that it allows inert" gas to be supplied from the generating plant to the discharge lines of the respective blowers, when the solenoid isnot excited. i

The lever 86 being swung to the right in the drawing and the solenoid circuit 94 therefore being open, the solenoidal valve is open. But if the percentage of inertness registered by the galvanometer rises from 38 to 65, contact of brush If the degree of "inertness of the gas circulating through the respective blowerdecreases slowlyuntil it reaches the low safe margin of 35%,

the brush 1! will contact with segment 18, the solenoid circuit is opened and the solenoidal valve opens, the degree of "inertness of the gas which moves from the respective blower through the respective discharge line being increased by the supply of fully inert gas from thegenerating plant. The galvanometer will consecutively register a higher degree of inertness until the upper margin of 65% has been reached again, when the supply through the solenoidal valve is shut o'fi.

An alarm 90 is connected in parallel with relay 83. It may be taken out of the circuit by opening switch 9|. When switch 9! is closed the alarm will be actuated whenever the inertness" of the gas circulating'through the respective blower is below the safe lower margin of 35%.

The arrangement of Figure shows the "inert gas generating plant located in an alternative position near the bow of the boat. From the reducing board 21 of the generating plant the inert gas passes in this modification to a main pipe line 92. Branches 95 of that pipe line run to each of the main tanks and to the pump room and are respectively-controlled by the solenoidal valves 51. Small motor driven pumps 93 are arranged near the unidirectional breathers 20 and they continuously supply a small amount of the gas to the vapor indicator 55. vWires connecting the vapor indicator 55 to the solenoidal valve 51 form part of the solenoid circuit 94.

Whereas any kind of an inert" gas may be used to create a safe atmosphere in the various spaces in which combustibles are stored or handled, the most economical gas used today for such purposes is the properly cleaned exhaust gas of an internal combustion engine. The arrangement of a generating plant for such gases has been described by me in Letters Patent No. 1,952,005, issued March 30th, 1934, entitled "Control for a producer of non-oxidizing gases and plants of this kind are indicated at 23 in Figures 1 and 2 near midship and in Figure 5 near the bow of a boat. Such a plant produces an exhaust gas, cleans it, tests it and automatically stores it in high pressure tanks 28. The high pressure tanks issue upon areducing valve board 21. The gas flows from the high pressure tank through the valves mounted on that board, and from there, at a reduced pressure,when the line pressure, at the point of use, drops below a predetermined pressure standard, to which the reducing valve is set,-into the main distributing lines 29.

In theabove cited prior patent it has been stated that any reliable apparatus serving for the determination of the carbon dioxide contents in a certain atmosphere may be satisfactory for checking the quality of the inert gas produced in the generating plant. Any such 'device, which is adapted for registering the carbon dioxide contents of an atmosphere, may also be used in the vapor indicators 55 which serve to check the quality of the gases in the spaces above the liquids in the tanks as well as the quality of the gas in the pump room i5. However, I illustrate in' Figure 6 of my drawings an apparatus which seems particularly adapted for the purpose of protecting spaces to. which I have referred in my introduction. In addition to reacting upon and registering the carbon dioxide contents of the atmosphere to be tested, this apparatus is also influenced by the inflammable gases which are apt to arise from the oil or gasoline stored in the various tanks of a tanker.

In observing the thermal conductivity of gases the value of the conductivity of a gas is compared with air and the observed or computed ratio is termed the factor of thermal conductivity of gas. The gases primarily coming into question for observation in considering the protection of tanks in which hydrocarbons are stored are carbon dioxide and hydrogen. The thermal conductivity factor of carbon dioxide is comparatively low and I have found that the protective quality of an exhaust gas is the greater, the larger the percentage of carbon dioxide contained therein. Since carbon dioxide primarily influences the thermal conductivity test of an exhaust gas, the actual percentage of carbon dioxide in an exhaust gas can be substantially directly observed and registered on a galvanometer by means of a Wheatstone bridge arrangement, The procedure in and the apparatus used for making such observations is described in detail in Technologic Paper No. 249 published by the Bureau of Standards of the Department of Commerce of the United States and a detailed description thereof will therefore not be necessary. vThe comparison gas is accommodated in the thermal conductivity unit 10, whereas the gas to be tested passes through the thermal conductivity unit II. The latter is therefore connected to one of the small pipe lines '|5 which issue from the discharge lines of the tanks and of the pump rooms. In the modification of Figure 5 the thermal conductivity unit H of the vapor conductivity 55 is connected to a small pump 93 which withdraws a small sample of the gas contained above the inflammable liquid in the tank, from a corner opposite the corner at which the supply of "inert gas issues into said space through the pipe 95. Whereas in the testing apparatus of my prior invention the testing or the exhaust gases only had to be considered and the dilution of said gases with air was largely the determining factor for the percentage of carbon dioxide observed, in this new application of a'thermal conductivity unit for determining the quality of gases withdrawn from the space above hydrocarbons the gases volatilized from the hydrocarbons must also be considered in the reading registered, and hydrogen and other gases given oil. by inflammable liquids indeed exert a great influence upon the'thermal conductivity of the atmosphere they are contained in.

Hydrogen has a high factor of thermal conductivity and its influence upon the reading observed is directly opposed to the deflection caused by carbon dioxide. The scale of the galvanometer 12 being empirically divided to register the quality of an inert gas from the center of the 7 in a harbor and when there is substantially no scale which would correspond to' the thermal conductivity of air mixed with just enough inert gas so as not to sustain free combustion, to a maximum inertness which would correspond to the highest possible carbon dioxide contents ordinarily observed in exhaust gases, the introduction of hydrogen or of gases which have similar thermal conductivity factors will tend to cause the deflection of the needle is in counterclockwise direction, so that the galvanometer will register less inertness inan inert atmos phere, as soon as hydrogen or similar inflammable gases are introduced into said atmosphere. The galvanometer is arranged to operate the collateral apparatus so as to preserve an average inertness of 50%. Assuming that there is an average inertness of 50%, the inertness registered will fall below the 50 calibration as soon as inflammable gases enter upon the therbeing automatically increased when inflammable gases are present.

The solenoidal valve 51 is shown enlarged in Figure 6 and the flow of gas pressure is indicated to take place from the right to the left. When the solenoid is excited the stem of the valve is lifted and the port'is closed, the valve seating therein from below, so that the supply of inert gas from the reducing valves, to the right, is shut ofl from the spaces above the liquids or from the pump room, to the left of said valve. The force with which the solenoid holds or retains the valve in its seat can be adjusted so that it is readily overcome by a certain drop if the pressure from the right to the left in said valve. This allows the solenoidal valve to be also used as a check valve, "inert" gas being admitted to the spaces above the liquids in the tanks, or to the gases circulating therethrough when the pressure drops below. a certain, fixed value. In a practical application of my invention I preferably use pressure control means which act independent of the quality-controlling.

solenoidal valves. Such means are not indicated in Figure 3,not to obscure the principle of the invention shown. But in Figure 4 a check or pressure regulating valve 20 is shown inserted between thepoint 91 of line 40 and the line 63 connecting the corresponding solenoidal valve to the manifold 58 and correspondingly the pipes v59, 50, Bi, and 62 may be connected by check or pressure in the tanks rises above a predetermined pressure in excess of normal atmospheric pressure, is removed from the deck of the ship.-

Owing to its heaviness that gas will drop onto the water alongside of the ship and it therefore will not inconvenience the crew of .the ship moving about on the deck. This featureis of particular importance when the ship is anchored wind to take away from the deck of the. ship gases which may prove to be annoying.

The small pumps 93 of Figure 5 drive samples of the gas'contained in the tanks above the inflammable liquid, and gases contained in the pump room near the top thereof, into the vapor indicators 55 where their quality of inertness is registered. Accordingto the quality registered, the solenoid circuit of the solenoidal valve 51, to which the impulses of closingv and opening the relay circuits by means of the contactor H are transmitted through the wires 94, will be operated. If the quality of the gas recorded is of insufiicient safety, the supply of gas from the reducing valve board 21 is supplied through the solenoidal valve into the spaces above the inflammable liquids or into the pump room and such a supplying of new inert gas will continue until the vapor indicator 55 again registers a high degree of safety in the atmosphere in the respective spaces. The pressure of the gas supplied from the reducing valve board slightly exceeds the pressure normally preserved in the spaces above the inflammable liquids and in the pump room and the valves 20 are set to release at a pressure between that of the gas'supplied from the reducing valve board and atmospheric pressure. The flow of "inert gas through the pipes 95 into the various spaces will therefore not be prevented by a buildingup of pressure 'in the respective spaces, but the gas of inferior quality will be breathed out" of the spaces above the inflammable liquids at the opposite ends. thereof, until a safe standard of inertness" has been reached in said spaces and the supply of new inert" gas is shut off by the solenoidal valves- 51!.

If the pressure in the spaces above the liquids rises above the pressure normally to be mainsucked in through the solenoidal valve in accordance with the action described above, or it enters through a check valve arranged in parallel with the solenoidal valve 51. The releasing of surplus pressure .from the pump room is not indicated in the drawing by check valves, but

ings around the port holes 33 or through other crevices and cracks. If such releasing should operate reversedly, sucking air into said room, the inert standard of safety of the atmosphere would automatically be restored since the inferior quality of the gas, as'sampled in the vapor indicator 55, would bring about a supply of new inert gas to the pump room from the reducing valve board. As an extreme measure of safety I may of course provide check valves on the pump rooms, as I have shown them in'connection with the'spaces abovethe inflammable liquids in the tanks. But such a measure will ordinarily not be necessary, because the gas in the pump room is not exposed to'the same amount of expansion and contraction due to temperature diflerences, which occurs in the spaces above the inflammable liquids in the tanks.

-Maintaining the gas in atank above an inflammable liquid at a fixed degree of inertness or at zero intrinsic inflnmmability, instead of providing a may inert" zone therein and of coin- 7 I such releasing may take place through the opensafety. It is also important from an economical point of view, because normally a very limited supply of inert gas is required to maintain the quality of the protecting zone. The necessity of introducing additional gas arises in my improvements primarily, whenja replacement of a volume of gas, which has been breathed out" on account of expansion, has to be made.

The system of Figure 5 requires however the release of a certain amount of the atmosphere contained above the inflammable liquid, when safe inertness" is to be reimparted to said atmosphere. The gas thus released may also contain vapors of the inflammable liquid and the inflammable liquid will automatically give off additional amounts of vapors until a normal saturation of the newly introduced inert gas has been attained. A part of the most valuable ingredients of the inflammable liquid, i. e., the parts which ordinarily have the highest'fiash-point are thereby removed from the inflammable liquid.

The quality of the inflammable liquid is thus impaired and I have succeeded in improving still further upon the system of Figure 5, by the system of Figures 1, 2, 3 and 4, in which substantially the same gas makes up the atmosphere above the inflammable liquids in the tanks, said gas being continuously circulated and restored to a pre-' determined inert quality during such circulation. In the drawings I show a central point at which the testing, controlling and circulating apparatus is located, 1. e., in the shafts l3 and it, above deck'32. Of course this arrangement and location of the apparatus may be modified in adaptation to the vessel or storage means, in connection with which it is used. The choice of the number of individual circulating systems shown has also been arbitrary; in the same manner in which I provide one individual circulating system for a pair of adjoining tanks, and in the manner in which I apply the circulating system to two adjoining tanks in a parallel arrangement, I may also use one system for a smaller or greater number of tanks and may connect the system to said tanks in a series arrangement. Likewise the protection provided for the tanks located along a longitudinal center line of the vessel may be extended to the wing tanks l0.

Although the description of the apparatus, as given above, explains many parts of the apparatus of Figures 1, 2, 3 and 4, I describe in the following the circuit of one circulating system, in order to ascertain the understanding of my invention: The pump 35 continuously withdraws the atmosphere contained in the pair oftanks II by means of the branches 5| and 52 of pipe line 41; at the discharge end of pump 35 a sample of the gas is by passed through the small pipe line 54 at a pressure which maybe largely controlled by dimensioning the conductors. Check valves 53 prevent a flow of the newly introduced gas in a direction opposite to that in which circulation is caused by the pumps. The small pipe line 54 introduces the by-passed gas into the thermal conductivity unit II and the quality of the gas thus tested, as compared with the comparison gas in thermal conductivity unit III, is registered by the galvanometer 12. The electrical parts of Figure 6 operatively connect the galvanometer 12 to the solenoidal valve S'Lwhich controls the supply of "ine gas from manifoldfl through pipe lines 63 and 56 into the discharge line 40 of stored in the tank culated back to the pair of tanks i1 and dis- I tributed thereinto by means of the branches H and 45 of pipe line 40.

When the pressure of the gas in tank ll above the inflammable liquids contained therein drops owing to a; temperature drop, the valve 20 between the point 91 of line 40 and the line 63 operates, or

' the solenoidal valve 51 connecting pipe line 63 to pipe line 56 functions as a check valve, as described above, and a supply of inert gas suflicient to restore atmospheric pressure in the tanks ll passes therethrough; when that gas pressure rises above atmospheric pressure the check valve 20 allows breathing out of the gas, overboard, until substantially atmospheric pressure is rell. Of course the gas breathed out of the tanks may be stored in gasometers or pressure tanks, and recirculated when pressure conditions in the storage spaces warrant it. I

The use of a circulating system of gas in connection with my invention brings about a great economy in the use of inert" gases and I therefore am in a position to provide comparatively small inert gas generating plants in connection with large vessels. Such smaller gas generating plants may not have a capacity sufficient to supply all the inert" gas which may be regasometers filled with inert" gas, which supply the bulk of the amount of inert gas required when the vessel is unloaded. The vapor indicators on the vessel may function as protective means when inert gas is admitted to the tanks from the gasometers arranged along the shore of the harbor. Insufficiency of quality of the gas supplied from shore or leakage of the supply line and connections will be indicated on the galvanometer and an alarm is given by the alarm 90, for as long a period of time as the quality of the gases in the tank is below a standard of 35%. The alarm may of course also be used during the ordinary operation of my invention to warn -the crew that the quality of the atmosphere in the testing method chosen allows a regular or continuous testing and the resulting registrations are adapted to control and to' be operatively connected with the control valve gears. If the exhaust gas of the internal combustion engine is used, any of the many carbon dioxide analyzers known to the art today may be adopted for a measurement of inertness. v 7

One particular modification of the apparatus is, under certain circumstances, of particular value for obtaining a high degree of safety in protecting combustibles. My thermal conductivity method may be combined with a carbon dioxide analyzer, the two kinds of tests being 75 i spanner v a from said tanks for its quality of sustaining comecarried on'alongside of each other, .one serving to measure the general quality .of the atmosphere above the combustibles and registering therefor;

generally, the degree of danger of the mixed gases, the other test registering the quality of inertness, only, of the atmosphere, without consideration of the inflammable gases which are contained therein. Such compounding, tests and corresponding modification of the operation of the control valve suggests itself in particular for spaces in which the inertness cannot be carried toan extreme limit of safety but where the a necessity of occasional entrance of an operator has to be considered a Such an arrangement could for applied tothe'pump room; the compounded registering means allow, differentially, a determination of the inflammable gases present and .under certain circumstances it may be advisable for the operator to flush out the atmosphere in the pump dial, 'as-shown, is exemplarly, only, and under varying conditions a higher or lower standard of safety may be adopted.

Although I have shown and described several specific form'sof embodiment of my invention in detail, -'yet I'do not wish to be limited thereby except as the state of the art and the .appfinded claims may require, for a large range ofemodiflcations and changes suggest themselves to the engineer and designer applying my invention to problems of protecting combustibles, without thereby bringing about 'a departure from the spirit andsco'p'e of my invention.-

What I desire to patent is: 1 a v 1. The method of protecting combustible liquids stored in tanks, comprising withdrawing from said tanksgas contained "in said tanks above said liquids, analyzing the gas withdrawn instance be bustion, registering said analysis, and injecting gas of inferior quality of sustaining combustion into said tanks above said liquids, said injecting of gas being automaticallycontrolled by said registering of said analysis.

2. The method of protecting'combust'ible liquids stored" in tanks, comprising withdrawing from said tanks gas contained in said tanks above said liquids, analyzing the gas withdrawn from said tanks forits 'inflammability, registering said analysis, and infecting gas of low quality of sustaining combustion into said tanks above said 1 liquids, said injecting of gas being automatically controlled by said registering of said analysis.

' 3. 'The method of preserving a standard of inertness in, the jatmosphere contained in an en-' closure and admixed with combustible gases,

comprising circulating said atmosphere in an endless circuit, observing the degree of inflammability of said circulating atmosphere by continuously registering the proportionate amount of carbon dioxide and combustible gases contained therein, and injecting inert gas into said atmosphere in conformity with said observations.

4-. The method of preserving a. standard of inertness in the atmosphere containedin an enclosure and admixed withcombustible gases, comprising circulating said atmosphere in an endless circuit, observing the degree of infiammability of said circulating atmosphere by continuously registering the thermal conductivity thereof, and injecting inert gas into said atmosphere in conformity with said observations? 5. Means for providing a protective gas zone 35 in an enclosure, comprising an endless pipe system through which the gas contained in said en-' closureis continuously circulated, means measuring the quality of inertness of the zone of gas of said enclosure, a source of inert gas, and valve and'admitting said inert gas to said enclosure'in conformity with said measurements.

.. WALTER J WILLENBORG.

. means connecting said source with said system, operatively connected with said measuring means

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