Tech Challenge 
Aging HVAC Systems and Possible Chemical Exposure The HVAC systems at Greenhouse Produce are beginning to show signs of age. Two of the most common gases produced by fuel combustion during the heating of the greenhouses are sulfur dioxide and ethylene. If an HVAC system is failing, these gases can flow into the greenhouses. Damage to plants can begin to occur after exposure to ethylene above 0.05 ppm and sulfur dioxide above 0.5 ppm. Danger to humans begins above 2 ppm for sulfur dioxide. Ethylene is known as an asphyxiant gas, so its danger to humans is relative to the amount of oxygen it displaces in the lungs. How can the producers determine if these two gases are present at levels dangerous to their plants and themselves? A. Use a Sensidyne® gas sampling pump and two detection tubes for ethylene (0.1 to 100 ppm) and sulfur dioxide (1 to 60 ppm). B. Use a gas monitor, such as the Drager CMS analyzer and two gas detection chips for ethylene oxide (0.4 to 5.0 ppm) and sulfur dioxide (5 to 150 ppm). C. Use a Photo Ionization Detector (PID), such as the ToxiRAE Plus pocket monitor. D. Use a gas sampling pump, such as the Drager accuro® pump kit, and two gas detection tubes for ethylene (0.2 to 5 ppm) and sulfur dioxide (1 to 25 ppm). Answers: A. Use a Sensidyne® gas sampling pump and two detection tubes for ethylene (0.1 to 100 ppm) and sulfur dioxide (1 to 60 ppm).
Correct. It is possible to detect these two gases at low enough levels to make sure both people and plants are safe. This will indicate if the HVAC system needs repair. B. Use a gas monitor, such as the Drager CMS analyzer and two gas detection chips for ethylene oxide (0.4 to 5.0 ppm) and sulfur dioxide (5 to 150 ppm).
Incorrect. Ethylene oxide is not the same as ethylene, and the sulfur dioxide chip does not register low enough ppm for adequate safety because 5 ppm is the lowest it will detect. C. Use a Photo Ionization Detector (PID), such as the ToxiRAE Plus pocket monitor.
Incorrect. Although this gas detector will measure ethylene, it will not detect sulfur dioxide. In addition, this detector is nonspecific, so it might detect gases other than ethylene that are nontoxic. D. Use a gas sampling pump, such as the Drager accuro® pump kit, and two gas detection tubes for ethylene (0.2 to 5 ppm) and sulfur dioxide (1 to 25 ppm).
Incorrect. This system can detect both types of gas but does not have the lowest range available. . |
