Development Of Portable Ammonia-air Tester

NH3 is a important kind of chemical product and has been used widely in production and living. It's a kind of gas which is achromatous and strongly stimulate feculent. It is lighter than air and is alkalescence. It'll canker and stimulate the skin which touchs it and will destroy endosmosis. NH₃ is a deliquescent air which is harmful to human's and animal's trachea and weakens the resistance of human to disease. When the chroma is very high, it can prevent the heart from flouncing. With the development of levelof life and requestment of higher quality of life, people bring forward higher standard for inspecting the chroma of ammoniacal air, especially,for inspecting the low chroma of ammoniacal air.At present, there are various kinds of ammoniac inspection device in the market .Some devices analysis the consistency of ammoniac in the way of colorimetry which analysis the consistency of ammoniac by color of the liquor. This device consists of lamp-house, integration photoelectricity sensor and microprocessor. Other devices consist of ammoniac sensor and integrate circuit, which is in the way of changing the consistency of ammoniac into analog signal that was sent to MCU by signal processor circuit and the consistency of gas will be displayed in the LCD by computing. In the aspect of collection gas, some devices use in pumping station and some devices use in pervasion station.The article recommends a portable Ammonia air tester which is based on the classical R/F transition circuit. The sensor's equivalent resistance is translated into impulse signal by multivibrator. The MCU calculates frequency. Then, the concentration of ammonia-air is acquired by interpolation.