Illustration of the structural principle of the smoke density meter

The smoke density testing-equipment' target='_blank'>tester is mainly composed of smoke box, sample holder, ignition system and photoelectric system. 1. Smoke box The structure of the smoke box is shown in the figure. The smoke box consists of a 300mmX 300mmX 790mm rust-proof metal plate with a Pyrex door. The smoke box is fixed at a size of 350mm×400mm× On a 57mm base, there is a controller on the base. The inside of the smoke box should have a surface treatment that protects the metal from corrosion. The smoke box has 25mm around the bottom×The remainder of the 230mm opening should be sealed. A 1700L/min exhaust fan is installed on one side of the smoke box, the air inlet of the exhaust fan is connected with the interior of the smoke box, and the exhaust port is connected with the fume hood. If the fume box is under a fume hood, it may not be necessary to connect it to a fume hood. There is a smoke-tight glass round window with an opening diameter of 70mm at the center position 480mm high from the base on the left and right sides of the smoke box door. Corresponding optical equipment and additional controls are installed at these positions and outside the smoke box. device. A replaceable white plastic plate is installed on the back of the smoke box. It is located in the center of the back panel of the smoke box at a distance of 480mm from the base, with a height of 90mm and a width of 150mm. Through it, an illuminated escape sign with red letters on a white background can be seen.“EXIT”typeface. The flame, smoke and combustion characteristics of the material can be easily observed on a white background. It is helpful to find the relationship between the visibility and the test value by looking at the safety exit signs. 2. The sample holder The sample is placed on a square frame with a side length of 64mm, and the square is 6mm long.×6mm×It is made of 0.9mm stainless steel grid, and the square bracket is located 220mm above the base and equidistant from each side of the smoke box. The steel wire grid is located in the stainless key frame slot. The stainless steel frame slot is supported by a steel rod handle fixed to the right side of the smoke box. Mounted on the same key rod handle, there is a similar stainless steel 7fimm below the sample holder The key frame slot, which supports a square asbestos plate. The asbestos plate can collect drips during the test. By turning the steel rod of the sample holder, the burning sample can be extinguished by falling into a tray with a small amount of water below. 3. The ignition system sample should be ignited by a propane flame produced by an igniter with a working pressure of 276 kPa. The gas should be mixed with the air when the gas passes through the 0.13mm diameter hole. Use the propane venturi to push the air and pass into the igniter together. The igniter must be designed to provide sufficient outside air. The igniter below the sample should be able to be quickly repositioned so that the axis of the igniter falls at a point 8mm above the base, the igniter extends diagonally at the back corner of the smoke box and is 45 mm from the base.°Tilt up. The outlet of the igniter should be 260mm from the reference point on the back of the smoke box. The duct on the outside of the smoke box should be at least 150mm long and should be able to direct air into the igniter. 4. The photoelectric system uses a light source, a photocell with a barrier layer and a temperature compensator to measure the percentage of the light beam passing through the 300mm smoke layer. The beam path propagates in the horizontal direction as shown. The light source is installed in a light source box protruding from the left wall of the smoke box, located at a height of 480mm above the base. The light source is a filament-intensive instrument bulb with a working voltage of 5.8V. The light source is a spherical reflector. Its power is provided by an adjustable voltage transformer. A lens with a focal length of 60-65mm focuses the beam on the photocell on the right wall of the instrument. Another box containing the photometer is mounted to the right of the smoke box. Photocells with barrier layers should have standard spectral responses. A circular grid box should be placed in front of the photocell to protect the cell from astigmatism. The grid should be dark polished. And the openings should be at least twice as deep as they are wide. The current induced by the photocell is displayed on the meter as the absorption rate of light. Photocells decrease linearly with increasing temperature, so compensation should be made. The operating temperature of the photovoltaic cell is not higher than 500 ℃. The meter should have two ranges. The range can be changed by switching the meter to one tenth of its sensitivity. When the smoke has accumulated to absorb 90% of the beam, it should be switched quickly to reduce the sensitivity of the meter to the basic value. To achieve this, the meter should be scaled from 90% to 100%, not from 0 to 100%.
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Many of the textile testing equipment listed here can be purchased for less money, but in general we recommend paying a slightly higher price for significantly improved performance. These are our top choices and their recommended configurations.