h. Fire-rated plywood. i. Fire-stopping for tray penetrations and sleeves. j. Racks with cable managers and power strips. k. Smoke detectors. l. Emergency-power-off station, with circuiting where required by Code. m. Maintenance receptacles on each wall. n. Backup power wiring to racks and equipment, twist-lock receptacles or hard wired. o. Security, electric door locks with key bypass, card reader, magnetic door switch. 5. Outside plant cable: a. Single-mode fiberoptic cable, non-LEC cable. b. Multimode fiberoptic cable, non-LEC cable. c. Copper cable, non-LEC cable. d. Terminations. Note that if gel-filled cables are used, extra terminations may be necessary to meet fire codes which require that gel-filled cables must terminate within 50 ft of entering a building. e. Fiber testing, OTDR. f. Copper testing, electronic cable tester. 6. Main communications room cable and equipment: a. Fiberoptic entrance facility. b. Protected-entrance terminals, PETs. c. Punch-down blocks.

Power roof ventilators are usually roof mounted and utilize either centrifugal or axial blade fans. Both types are generally used in low-pressure exhaust systems for factories, warehouses, etc. They are available in capacities up to about 30,000 ft3 /min. They are, however, limited to operation at a maximum pressure of about 1/2 in water gage. Powered roof ventilators are also low in first cost and low in operating costs. They can provide positive exhaust ventilation in a space, which is a definite advantage over gravity-type exhaust units. The centrifugal unit is somewhat quieter than the axial-flow type. Fans vary widely in shapes and sizes, motor arrangements and space requirements. Fan performance characteristics (variation of static pressure and brake horsepower) with changes in the airflow rate (ft3 /min) are available from fan manufacturers and are presented in tabular form or as fan curves. Dampers. Dampers are mechanical devices that are installed in a moving airstream in a duct to reduce the flow of the stream. They, in effect, purposely produce a pressure drop (when installed) in a duct by substantially reducing the free area

8.21.3 Diaphragm Action of Decks In addition to their normal function as roof panels under gravity loading, steel roof deck assemblies can be used as shear diaphragms under lateral loads, such as wind and seismic forces. When steel roof deck is used for these purposes, special attention should be paid to connections between panels and attachments of panels to building frames. For design purposes, see SDI Diaphragm Design Manual. 8.21.4 Details and Accessories of Steel Roof Deck In addition to the use of nesting or upstanding seams, most roof-deck sections are designed so that ends can be lapped shingle fashion. Special ridge, valley, eave, and cant strips are provided by roof-deck manufacturers (Fig. 8.16). Roof decks are commonly arc welded to structural steel supports with puddle welds at least 1/4 in in diameter or with elongated welds of equal perimeter. Electrodes should be selected for amperage adjusted to fuse all layers of steel roof decking to supporting members without creating blowholes around the welds.Welding washers are recommended for thicknesses less than 0.028 in. Fillet welds at least 1 in long should be used to connect lapped edges of roof