AN ANALOGUE-ADDRESSABLE OPTICAL SMOKE AND HEAT DETECTOR. THE DETECTOR UTILISES THE LIGHT SCATTER SENSING PRINCIPLE, USING BOTH INFRA-RED AND BLUE LIGHT EMITTING DIODES (LEDS) AND A PHOTO-DIODE AS THE SMOKE SENSING ELEMENT. THIS PROVIDES A MORE ACCURATE MEASUREMENT OF THE SIZES OF PARTICLES FOUND WITHIN ITS SENSING CHAMBER. BY CALCULATING THE RATIO OF THESE LIGHT SOURCES, WHICH OPERATE AT DIFFERENT WAVELENGTHS, IT CAN DETERMINE THE PARTICLE SIZE AND THUS DISTINGUISH BETWEEN SMOKE AND NON-COMBUSTION PRODUCTS SUCH AS STEAM DROPLETS OR DUST. HEAT DETECTION IS MADE USING A THERMISTOR OF LOW THERMAL MASS, WHICH CAN BE SET TO DETECT TEMPERATURE RATE OF RISE OR TO TRIGGER AT A FIXED AMBIENT TEMPERATURE. THE PRODUCT COMPRISES A CIRCULAR ABS-TYPE PLASTIC CASING CONTAINING METAL FASTENINGS AND CONNECTING TERMINALS PLUS A POPULATED PRINTED CIRCUIT BOARD WITH THE SMOKE SENSING CHAMBER ATTACHED; PLUS AN EXTERNALLY MOUNTED THERMISTOR AND A FURTHER EXTERNAL 360-DEGREE LED. IT ALSO INCORPORATES A CHEMICALLY-ETCHED STAINLESS STEEL INSECT SCREEN TO MINIMISE INGRESS OF INSECTS AND AIRBORNE CONTAMINANTS. THE PRIMARY FUNCTION OF THEDE 24680/14-1 PRODUCT IS THE DETECTION OF SMOKE. THE DETECTOR IS USED IN CONJUNCTION WITH A FIRE ALARM SYSTEM CONTROL PANEL. IT DOES NOT CONTAIN AN INTEGRAL RECORDING DEVICE NOR ANY AUDIO-VISUAL WARNING EQUIPMENT. IT HAS REMOTE INDICATOR OUTPUT. THE DETECTOR MAY BE SOLD SINGULARLY IN A SMALL CARDBOARD BOX BUT IS MORE COMMONLY DESPATCHED WITHIN LARGER CARDBOARD CARTONS CONTAINING 10 OR 100 UNITS.

CLASSIFICATION HAS BEEN DETERMINED IN ACCORDANCE WITH THE FOLLOWING: GENERAL INTERPRETATIVE RULES (GIR)S GIR 1 HAS BEEN USED TO CLASSIFY THIS PRODUCT BY THE TERMS OF HEADING 9027 - INSTRUMENTS AND APPARATUS FOR PHYSICAL OR CHEMICAL ANALYSIS (FOR EXAMPLE, POLARIMETERS, REFRACTOMETERS, SPECTROMETERS, GAS OR SMOKE ANALYSIS APPARATUS); INSTRUMENTS AND APPARATUS FOR MEASURING OR CHECKING VISCOSITY, POROSITY, EXPANSION, SURFACE TENSION OR THE LIKE; INSTRUMENTS AND APPARATUS FOR MEASURING OR CHECKING QUANTITIES OF HEAT, SOUND OR LIGHT (INCLUDING EXPOSURE METERS); MICROTOMES GIR 5 (B) HAS BEEN USED TO IDENTIFY THE PACKAGING GIR 6 HAS BEEN USED TO CLASSIFY THE GOODS TO SUBHEADING LEVEL 9027 10 - GAS OR SMOKE ANALYSIS APPARATUS CN CODE 902710 10 - ELECTRONIC ALSO CLASSIFIED IN ACCORDANCE WITH: NOTE 3 TO CHAPTER 90 ADDITIONAL NOTE 1 TO CHAPTER 90 HARMONIZED SYSTEM EXPLANATORY NOTES (HSEN) (9) TO HEADING 9027