US 3673424 A
A safety lighting system for a chain of lamps, each of which is housed within a hermetically sealed translucent tubular housing member. A control box is provided for supplying electrical power to the lamps in the lighting assemblies. A pressurized source of inert gas is fed through the control box at a predetermined pressure and through each of the sealed translucent tubular housing members. A pressure sensitive switch is provided in the control box for disconnecting the electrical power to the lamps when the pressure of the inert gas within any of the translucent tubular housing members drop below a predetermined level.
Description (OCR text may contain errors)
United States Patent Phlieger, Jr. 1 June 27, 1972 s41 PRESSURIZED LIGHTING SYSTEM 3,508,236 4/1970 Adams; ..340/240  Inventor: Graydon A. Phlleger, Jr., Cocoa, Fla. Primary Examiner Heman J Hohauser  Assign: The Unhed Sums of Amerlm as Attorney-James O. Harrell and John R. Manning represented by the Administrator of the National Aeronautics and Space Adminls-  ABsrRACT tratlon A safety lighting system for a chain of lamps, each of which is housed within a hermetically sealed translucent tubular hous-  1971 ing member, A control box is provided for supplying electrical  A N 114,849 power to the lamps in the lighting assemblies. A pressurized source of inert gas is fed through the control box at a predetermined pressure and through each of the sealed translucent tu-  US. Cl ..307/118, 307/92, 340/240 bular housing membels A pressure sensitive switch is [5 l 1 Int. Cl. vided the control box for disconnecting the electrical power Field of Search to the lamps when the pressure of the inert gas within any of 340/240, 242 the translucent tubular housing members drop below a predetermined level. 56 R f ces C'ted 1 e 3 Claim, 4 Drawing Figures UNITED STATES PATENTS 3,164,821 1/1965 Broder et a1. ..307/l 18 X ru U 42 OFF P'A'TENTEDJUNN I972 SHEET 10F 2 INVENTOR. GRAYDON A.PHL|EGER JR.
gum/4! 6Q M ATTORNEYS PRESSURIZED LIGHTING SYSTEM The invention described herein was made by an employee of the United States Government, and may be manufactured and used by or for the Government for Governmental purposes without the payment of any royalties thereon or therefor.
The invention relates to a safety lighting assembly, and more particularly to a lighting assembly which includes a plurality of lamps that are maintained in a pressurized atmosphere of inert gas. When the pressure within the lighting assembly drops below a predetermined level the electrical power to the lamps is disconnected.
The construction, maintenance and servicing of space vehicles and launch vehicles necessarily requires that activities take place within the vehicles themselves, and often in a hazardous environment. These hazardous environments may include environments where there is a higher than normal concentration of oxygen, hydrogen, or combinations of the explosive gases. If the explosive gas mixture were allowed to enter into lighting assemblies where electrical power is being utilized to illuminate the lamps, it is possible, as a result of faulty wiring, overheating lamps, etc., that an explosion may occur endangering personnel within the vicinity as well as damaging expensive equipment. It has also been found that lamps which are confined to restricted housing tend to overheat which shortens the life span of such. If condensation is allowed to collect within the lighting assembly, such in turn, affects the illumination of the lighting assembly, as well as permits corrosion of certain connections which, if allowed to persist, would possibly interfere with the operation of the lighting assemblies.
In accordance with the present invention, it has been found that difficulties encountered in lighting assemblies which include a protective casing, may be overcome by providing a novel safety lighting system. This lighting system includes the following basic components: l) A plurality of lighting assemblies, (2) each of the lighting assemblies including a hermetically sealed translucent tubular housing, (3) caps carried on each end of the tubular housing members, (4) an electric lamp carried within each of the housing members, (5) a source of electrical power, (6) means for coupling the source of electrical power to each of the lamps in the tubular housing members for illuminating the lamps, (7) a fitting extending through each of the caps for providing communication with the interior of the housing member, (8) a pressurized source of an inert gas, (9) tubular means coupled to the fittings on the caps of the lamp assemblies for connecting the lamp assemblies within a series chain, (10) means coupling the pressurized source of inert gas to the tubular means for causing the gas to flow through the tubular housing of the lighting assemblies, (1 l) a pressure activated switch coupled to the tubular means and the source of electrical power for disconnecting the source of power from the lamps when the pressure of the inert gas flowing through the lighting assemblies drops below a predetermined level, and (12) a control box interposed between the electrical power source and the lamps, as well as the pressurized source of an inert gas and the tubular means for disconnecting the source of electrical power from the lamps when the pressure within the lighting assemblies drops below a predetermined value.
Accordingly, it is an important object of the present invention to provide a safety lighting system which can operate in hazardous environments that disconnects power from the lamps responsive to the pressure of inert gas passing through the lighting assemblies dropping below a predetermined level.
Another important object of the present invention is to provide a simple lighting assembly wherein, inert gas is passed through the assemblies for aiding in cooling lamps carried therein, preventing a hazardous environment from develop ing, as well as minimizing condensation within the lamps.
Another important object of the present invention is to provide a safety lighting system which can be used in hazardous environments, wherein if any of the lighting assemblies become defective as a result of a drop in pressure of inert gas passing therethrough, all of the lighting assemblies are disconnected from the source of power provided for the lamps.
Still another important object of the present invention is to provide a safety lighting system which includes a plurality of lighting assemblies that can be connected in a suing so as to be conveniently positioned in the area which is desired to be illuminated.
Still a further object of the present invention is to provide a safety lighting system which includes a plurality of lighting assemblies which are continuously purged with an inert gas, such as dry nitrogen, that prevents hazardous gases from leaking into the lighting assemblies and possibly causing an explo- .sion.
Other objects and advantages of this invention will become more apparent from a reading of the following detailed description and appended claims taken in conjunction with the accompanying drawings wherein:
FIG. 1 is a front elevational view illustrating a control box utilized with the invention,
FIG. 2 is a schematic flow diagram for the inert gas,
FIG. 3 is a schematic electrical diagram of the lighting system, and
FIG. 4 is an elevational sectional view of a lighting assembly which may be utilized in the present invention.
Referring in more detail to the drawings, there is illustrated a safety lighting system which utilizes hermetically sealed lighting assemblies. One suitable lighting assembly which is capable of being purged by gas and utilized in the present invention, is disclosed in my copending United States patent application entitled INTERNAL WORK LIGHT, bearing Ser. No. 752,729.
Referring in more detail to FIG. 1, there is illustrated a control box which contains the controls and indicators forming a part of the safety lighting system. Included in the front of the control box are quick disconnect fittings 10, 12 and 14, provided for installation and removing of the hoses which carry the inert gas nitrogen. The inert gas nitrogen may be supplied from any suitable source, such as the pressurized bottle 16. The gas is coupled by means of a hose 18 to the input quick coupling fitting 10'carried on the front of the control box 20. After the gas flows through various components, such as illustrated in FIG. 2, it leaves the box through the quick coupling fitting l2. Tubular means, such as hoses 22, are coupled to the quick coupling 12 and supplies the gas to lamps 24, which are connected in a series chain. The gas flows in a continuous stream through the lamps and is returned back to the control box through fitting 14, and is exhausted from the control box through a vent tube 26. During operation of the lighting system a continuous flow of gas flows from the bottle 16 through all of the lamps 2A in series, and out the vent 26.
Various components are provided in the control box for monitoring and controlling the flow of the gas through the lamp assemblies 24. As the gas enters the control box 20 through the tube 18 it passes through a pressure regulator 28 that is adjusted to read approximately l5 p.s.i. on the gauge 30. The gas is then fed to a vent valve 32, which when open, allows the lines 18 flowing through the control box to be purged, as well as the box 20 itself. When the vent valve 32 is closed the gas flows through line 18a, outlet valve 34, from the control box 20 via means of the fitting 12. The gas then flows through hose 22, lamps 24, andis returned to the control box 20 through the return fitting 14. Another regulated valve 36 is interposed in the hose coupled between a pressure switch 38 and the return gas fitting 14.
Since the outlet valve 34 is open and the vent valve 32 is closed, the gas purges all of the hoses and lamps in the system. Normally it is recommended that this purging operation be allowed to continue for 5 minutes to insure that the inert nitrogen gas replaces all of the air in the lamp assemblies 24. This purging operation takes place with the hose 22, which returns back to the return fitting l4 disconnected. After the lamps have been purged the return hose 22 is reconnected to the fitting l4 and the pressure of the gas flowing through the hose 22, which is under control of regulator 28, is reduced to approximately 7 p.s.i. The gas is allowed to flow through the regulator 36 and the pressure switch 38 out of the vent hose 26 at this pressure setting for approximately five additional minutes to make certain the complete system is purged of air. The regulator 36 is adjusted so that the pressure entering pressure switch 38 when the device is operating properly remains above 3 p.s.i.
The electrical schematic for the system is illustrated in FIG. 3. A 1 volt A.C. source, generally designated by the reference character 40, is coupled via leads 42 and 44 to the input power connector 46. The lamp 48 is connected via leads 50 and 52 between the input leads 40 and 42 for indicating when there is power being fed into the control box. Interposed in lead 42 is a contact 54 which is operated by the pressure switch 38. When the pressure of the inert gas flowing through the system, and in particular hoses 22, is above 3 p.s.i., the contact 54 is connected to terminal 56 which allows power to be supplied to the lamps 24 which are connected in parallel between leads 42 and 44. This also illuminates lamp 58 which indicates that the pressure is normal and power is being supplied to the control panel. A manually operated switch 60 is interposed in lead 42 for manually turning on and off the lamps 24. When the switch 60 is closed, as shown in the drawing, lamp 62 on the control panel is illuminated indicating that the lamps 24 are being supplied with power.
If the pressure in the lamps 24 or in the hoses 22 drops below the predetermined desired setting of 3 p.s.i., the pressure switch causes contact '54 to move to the left disconnecting power from the lamps 24 and illuminating the below normal lamp 64.
As can be seen from reviewing the schematic diagrams of FIGS. 2 and 3, the lamps 24 from a pneumatic standpoint are connected in series, whereas, from an electrical standpoint they are connected in parallel.
Referring now to FIG. 4 of the drawings, tube light 24 is shown to include one end cap 66 and a second end cap 68 that are attached to a substantially light transparent plexiglass tube 70 by threads 72. Grooves 74 may be provided in end caps 66 and 68 for a purpose to be more fully understood hereinafter. End cap 66 has central aperture 76 and apertures 80, which provide access for rivets 86 to fixedly attach retainer plate 82, end cap 66, and chassis 84 to one another.
Chassis 84 includes longer upright flange 88 and shorter upright flange 92 extending from body 90. Flange 88 attaches to end cap 66 by rivet 86. Ballast 94 and starter socket 96 are rigidly secured to body 90 of chassis 84 and are supported thereby. Starter 98 is mounted in socket 96. Starter socket 96 and ballast 94 are attached to chassis body 90 by conventional devices.
Bi-pin lamp holders 108 are connected to a pair of stabilizer plates 104, slightly less in diameter than the inner diameter of tube 70, by nuts and bolts 110. One stabilizer plate 104 is secured to shorter upright flange 92 by bolts 106 to thereby provide a rigid connection between that stabilizer plate 104, chassis 84, and end cap 66.
Three longitudinal, electrically conductive rods 112 have heat shrinkable tubing 114 substantially covering their length between stabilizer plates 104. Threads 116 on the ends of rods 112 receive nuts 118 to securely and fixedly attach stabilizer plates 104 to one another and to chassis 84 as noted hereinabove. Fluorescent lamp 120 is mounted in bi-pin lamp holders 108 to complete the inner structure of tube light 24.
A radio frequency interference (RFI) shield 71 having an outer diameter substantially equal to the inner diameter of tube 70 may be utilized within tube 70 and surrounding the hereinabove described internal structure of tube light 25. Alternatively, RFI shield 71 could be of slightly greater diameter than the external diameter of tube 70 and held in place by grooves 74 in end caps 66 and 68. This construction prevents radiation of radio frequency interference which is created by fluorescent lamps and which would otherwise, cause discrepancies in the electronic recording and other equipment utilized in the vicinity of space vehicles where tube lights 24 may be used.
A floating end ring 124 fits around and is slidable on end cap 66. Fixed end ring 126 fits on one end cap 68 by a threaded engagement with bulkhead connector 132. Fixed end ring 126 has chain 128 attached thereto with receptacle protection cap 130 attached to the end of chain 128 to provide an easily and readily accessible protector for connector 132 when the latter is not in use.
The internal wiring of the light assembly is not illustrated since it is connected up through use of the rod 60 in the conventional manner that fluorescent lamps are wired with the ballast 94 and starter 98. The wires coming from the power source, which is shown schematically in FIG. 3, are fed in through the connector 132. One suitable way of wiring the lamp is illustrated in my copending United States patent application bearing Ser. No. 752,729.
Referring again to FIG. 2, purge gas fittings 134 extend through end caps 66 and 68 and permit connection of purge gas hoses 22 to thereby permit purge gas, such as dry nitrogen, to flow into the interior of tube 70 and thereby provide an inert ambient environment for the electrical system of the tube light 24. The conduits 22 extend from the control box as shown in FIG. 1, into a first tube light 24 and from that tube light to the next tube light 24 in the string. Such system may be continued to the extent desired with observance of electrical principles to prevent overload of any power system or circuitry being used to operate the system.
As best seen in FIG. 2, lanyard 102 may be attached to and extend between floating end ring 124 and fixed end ring 126 to provide for suspension of tube light 29 in any given work area.
The purging gas flowing through the lighting assemblies 24 creates an inert ambient environment which isolates the electrical components within the lamp assemblies 24 from explosive environments that the lamp may be utilized in. The purging gas also cools the lamps 108, prevents condensation within the lamps, and as a result, minimizes corrosion of components within the lamp assemblies.
While a preferred embodiment of the invention has been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.
1. A safety lighting system comprising:
A. a plurality of lighting assemblies;
B. each of said lighting assemblies including a hermetically sealed translucent tubular housing member,
C. caps carried on each end of said tubular housing members,
D. an electrical lamp carried within said housing member,
E. a source of electrical power,
F. means for coupling said source of electrical power to each of said lamps in said tubular housing members for illuminating said lamps,
G. a fitting extending through each of said caps for providing corrununication with the interior of said housing member,
H. a pressurized source of inert gas,
I. tubular means coupled to said fittings on said caps of said lamp assemblies for connecting said lamp assemblies in a series chain,
J. means coupling said pressurized source of inert gas to said tubular means for causing said gas to flow through said tubular housings of said lighting assemblies, and
K. a pressure activated switch coupled to said tubular means and said source of electrical power for disconnecting said source of power from said lamps when the pressure of said inert gas flowing through said lighting assemblies drops below a predetermined level,
L. whereby the interior of all of said tubular members must be pressurized with said inert gas in order for any of said lamps in said lighting assemblies to be illuminated.
2. The safety lighting system as set forth in claim 1 further comprising:
A. a regulator interposed between said pressurized source of inert gas and said tubular means for maintaining the pressure of said inert gas within said tubular members at a predetermined level.
- 3. The safety lighting system as set forth in claim 2 further comprising a control box,
A. said control box having an input receptacle for being coupled to said source of electrical power,
B. an output receptacle for supplying electrical power to said lamps,
C. said pressure regulator being carried in said control box,
D. a pressure gauge coupled to said regulator,
E. a gas input connector carried by said control box communicating with an input of said regulator and said pressurized source of inert gas,
F. a gas output connector carried by said control box communicating with an output of said regulator,
G. said tubular means being connected to said gas output connector for receiving said inert gas from said pressurized source through said control box, and
H. said pressure switch being carried in said control box for disconnecting said electrical power supply from said output receptacle responsive to the pressure of said inert gas within said tubular member dropping below a predetermined level.