Public Address system

The Public Address system shall be a complete system for amplifying sound signal from

microphones, background music source and distribute them to loud speakers at various

locations with provision to distribute sound on selective and zonal basis as shown on the

riser diagram.

SYSTEM COMPONENTS:

-          Microphones ( wire & wireless )

·         Types:

-          Dynamic microphones

-          Condenser microphones

-          Ribbon microphones

·         Specification

-          Sensitivity

-          impedance

-          Speakers

·         3 types ( wall mounted, surface mounted & recessed mounted )

·         Cover area approximately about 30 meter square and located every 6 meter at corridor.

-          Amplifiers

-          is an active component that increases the output signal of a sound source (e.g. microphone) and passes its output signal to a sound transducer (e.g. loudspeaker).

-          Capacities

( 120w, 240w............)

-          Matrix

§  The main unit for the system which work as the interface between the system inputs as ( microphone, radio & CD player ) and the ouput units as speakers

-          FM\AM radio

-          CD\DVD Player

-          Volume control ( attenuator )

·         Located at closed rooms and it have different wattage capacities depend on number of speaker connected to volume control.

-          Network audio adaptor

·         Used only in IP public address

-          Rack

·         All previous devices will be located inside the rack which will be located in the main control room of the project

-          Types of cable used in public address system

·         Shielded twisted pair cable 2 x 1.5 mm   

-          Types of conduits  used in public address system

·         PVC Conduits

·         EMT Conduits used in Exposed installation when using public address in voice evacuation

·         UPVC Conduits used in outdoor installation

Fire alarm system-design secrets

Addressable  system design secrets:

·      Distance between Smoke Detector mustn’t exceed 10 m to avoid dead area between detectors

·      Distance between heat Detector mustn’t exceed 7 m to avoid dead area between detectors

·      Fire detector must be mounted at least one meter from any forced air inlet.

·      Ramps at car parking must be covered by heat detectors

·      Voice evacuation located at escape stair must be in a separate loop.

·      Fire fighter telephone must be located at elevator lobbies & pump rooms.

·      Each fire loop must have 20% spare capacity.

·      Access control system ( ACS ), elevator, Door holder,Public address system ( PA ), exhaust fan’s, Air Handling Units( AHU’S ) connected to fire alarm system via control module ( CM )

·      Fire fighting system( FM200, CO2, Sprinkler system( flow switch & Tamper switch ) ) connected to fire alarm system via monitor module ( MM ).

·      Alarm bell located at 2200mm above finished floor level.