Smoke Density Apparatus is designed to measure the Smoke Density from the burning or decomposition of plastics as per the requirements of the ASTM D-2843. The apparatus consists of a Smoke Density Chamber and control console. The chamber is made out of 14SWG Aluminum sheet and is of 300x300x790mm (±5mm) size. The front side of the chamber is provided with hinged door fitted with glazed heat-treated toughened glass. The chamber rests on a strong base also made of 14 SWG Aluminum sheet. The Chamber is sealed except for 25 by 230mm openings on the four sides of the bottom of the chamber. A 1700 liters/min. blower is mounted on one side of the chamber. The inlet duct to the blower is equipped with a close fitting damper. The two adjacent to the door are fitted with 70-mm.-diameter Smoke tight glazed glass windows centered 480 mm above the base. At these locations and outside the chamber cubical boxes containing the light source with necessary lenses and mirror on one side and a special photocell with a set of baffles to prevent stray light, on the other side are fitted. A removable white plastic plate is attached to the back of the chamber. This is a 90 by 150mm clear area centered about 480mm above the bottom of the chamber through which is seen as an illuminated white on red EXIT sign. The white background permits observation of the flame, smoke and burning characteristic of the material. The viewing of the exit sign helps to correlate visibility and measured values.The specimen is supported on a 64mm square of 6 by 6mm 0.9mm gauge stainless steel wire cloth 220mm above the base and equidistant from all sides of the chamber. This screen lies on a stainless steel bezel supported by a rod through the right side of the chamber. From the same rod a similar bezel is located 76 mm below. By rotation the specimen holder rod, the burning specimen can be quenched in a shallow pan of water positioned below the specimen holder. The specimen is ignited by propane/LPG flame from a burner operating at a pressure of 276Kpa (40PSI). The fuel is mixed with air that has been propelled through the burner by the venturi effect of the propane/LPG as it passes from a 0.13mm diameter orifice. The light source is fitted inside the cubical box on the left hand side of the chamber. It consists of a lamp with a regulated power supply of 5.3 to 7volts, and fitted with a reflector mirror, and a converging lens. The reflector lens arrangements make the light been slightly converging and throwing a powerful light beam on the photocell housed in the right hand side box.