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1945 Theatre Catalog, 4th Edition, Page 523 (497)

1945 Theatre Catalog, 4th Edition
1945 Theatre Catalog
1945 Theatre Catalog, 4th Edition, Page 523
Page 523


1945 Theatre Catalog, 4th Edition, Page 523

Standards of the National Board of Fire Underwriters for the installation of airconditioning, warm-air-heating, air-cooling, and ventilation systems were modified to read as follows:

Electrical wiring and equipment shall be installed in accordance with the National Electric Code. Lamps within the enclosure of the conditioning system shall be enclosed in fixtures of the marine (vaportight) type-except that germicidal lamps of a type not using filament, and which operate at relatively low exposed surface temperatures, need not be so enclosed.

The only material, classed as combustible and which may be placed within the airduct in the typical lamp installation, is the insulation on the wires used for connecting the receptacles or sockets supporting the lamps. Normally the current-regulating transformers required are placed outside the duct and only the high tension wires leading to the receptacles are within the enclosure. Where insulated wires are used, they must be Type GTIO-5 gas-tube sign cable and run in enclosed raceways as a protection against abrasion and to prevent smoke being carried into the air duct and distributed throughout the theatre if the insulation should become ignited.

Connecting the receptacles with No. 10 A. W. G. bare copper wire eliminates combustible insulation within the air duct and reduces installation costs. The essential insulation is obtained by maintaining a spacing of at least one inch

TYPICAL ARRANGEMENT OF STERILAMPS in o 30x30-inch duct is shown in these sketches. There are 36 30-inch Steriiumps, set on 10-inch centers. In this air-conditioning system the volume of air is listed as 6,250 cubic feet a minute, with a velocity of 1,000 feet a minute. To accommodate the 30-inch Sterilamps, the height

BAFFLES TO MINIMIZE AIR ,FLOW AROUND SOCKETS

FLOW ..

L.

between the wire and any grounded metals. Non-combustible, non-absorptive insulators, such as have been used in neon signs are spaced at intervals of not more than 18 inches and not more than 6 inches from a terminal other than that of an electrode terminal. 0rdinarily, electrode terminals, designated Bryant LD-75, are spaced 6 to 15 inches, and so intermediate insulators are not required.

Transformers may be enclosed singly or in groups in metal enclosures, mounted on the top or sides of the air duct. The supports for electric receptacles connected with bare wire may consist of simple L-shaped brackets to give the minimum spacing of one inch between wire and any grounded metal.

Primary circuits are so arranged that no group of transformers on any one circuit shall require in excess of 15 amperes. As the primary current on a 115-volt circuit required by an ST-90 transformer, operating four 30-inch Sterilamps, is not more than 1.5 amperes, the maximum number of such transformers on a single circuit is ten. It is desirable to keep the number of transformers to the circuits at eight or less, to permit greater flexibility in operating and testing.

In order to see the groups of lamps to determine if they are all in operation, windows of wired glass are provided. As ordinary and wired glass will not

at'x I6" wmoow IN EACH DOOR

SIDE VIEW AIR

TRANSVERSE BAFFLE

FOR L075 SOCKET

SECTION A-A

1945-THEATRE

CATALOG

L075 SOCKET

HOLE DETAIL FOR

transmit ultraviolet radiation, no bactericidal rays escape through the windows. Wired glass is required for mechanical strength and resistance to shattering to prevent the spread of fire if flames are drawn into the duct. The Underwriters specify that no window shall exceed 720 square inches in area. Windows must be fitted air-tight to prevent leakage. If gaskets are used they must be of felt or synthetic material not adected by ozone.

Service doors of sufficient size and number are required to permit reaching and replacing any lamp in a group. As the intensity of ultraviolet radiation is high and since bare conductors may be used in the radiation chamber, it is necessary to provide interlocking switches on the service doors to open the primary circuit supplying the transformers when any service door is opened. Such switches must be listed by the underwriters and have a capacity at least twice that of the current rating of the circuit controlled. These safety features prevent a person, entering the radiation chamber, from being exposed to the high intensity radiation or possible contact with a 3,000-volt wire.

For testing purposes, the circuits may be arranged so that a group of four or eight lamps, operated from one or two transformers, may be put into operation by authorized persons and checked for ultraviolet output.

of the irradiation chamber has been increased from a diameter of 30 inches to 36 inches. Note should be given to the arrangement of the doors in the ducts that permit easy servicing of the equipment. (All drawings and photographs have been submitted for use by the Westinghouse Electric Corporation's Lamp Division.)

COVERS FOR TRANSFORMERS AND WIRING

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24"x24" STERILAMP SERVICE noon WITH INTERLQCK To OPEN ALL PRIMARY CIRCUITS

LONGITUDINAL BAFFLE FOR L075 SOCKET AIR FLOW PARALLEL TO BAFFLE
1945 Theatre Catalog, 4th Edition, Page 523