Portable Gas Detector

1. Client:Senior Design Project: Dec. 03-11 Faculty Advisors: Dr. Ratnesh Kumar Dr. Nicola Elia Portable Gas Detector Team members: Sven Soell EE Miao Qin CprE Hwa-Sung Ryu CprE Pek-Yee Teoh EE Abstract In most homes combustion gases are produced by appliances such as gas-fired furnace, boiler, or water heater or other fuel-burning devices. Normally, these combustion products — which can include both visible smoke and various invisible gases — should be vented to the outdoors. Unfortunately, they may instead escape into your home, where they could raise a variety of health and other concerns. Since toxic elements present in combustion gases are hardly detectable with human senses, this project shall implement a domestic gas detector which shall detect and monitor gases such as carbon monoxide and methane and warn the owner when a certain gas concentration is exceeded. • Measurable Milestones • Project definition • Implement testing circuit for sensor and micro controller • Test gas sensor with a reference device • Build case and write documentation Proposed Approach Sensory The gas detector shall be implemented using semiconductor sensors which offer low cost, long life, and good sensitivity to the target gas. The concentration of the gas will be determined via a unique relationship between the concentration of the gas and the internal sensor resistance. The gas sensor will be implemented in a circuit as shown in Figure 1. Data Acquisition and Display For the data acquisition a microcontroller shall be used. The controller will include an A/D converter for signal conversion and functions to address a display. To display the target gas concentration, a LED display will be used.The overall schematics is shown in Figure 2. Figure 1: Sensor circuit Figure 2: Overall schematics • Introduction • Problem Statement • Design and implementation of a portable gas detector which • detects CO and methane and displays their concentrations on a • display and warns the user via an audible alarm • The detector will consist of three parts: • 1. Sensory for detection of the target gas • 2. Data acquisition via a micro controller • 3. Display of target gas concentrations • Operating Environment • Residential domains • Normal household conditions • Intended Users and Uses • Home users who use fuel burning devices • To detect and monitor carbon monoxide and methane • Assumptions and Limitations • The gas detector shall be used for domestic use only • Correct positioning of the detector according to the target gas • The temperature does not exceed 40C° and dip below -5C° • No long term exposure in adverse environment • No excessive vibrations or contact with water • Expected End Product • A portable gas detector that detects and monitors CO and • methane and displays their concentrations on a display • Batteries and operating manual • Technology Considerations • Infrared, electrochemical, catalytic and semiconductor sensors • Computer based data acquisition using Labview • Testing Approach • Create an artificial environment with the target gases • Test the gas detector and compare values with a reference system • Client demonstration testing Schedules, Financial Resources, Personnel Effort • Project Requirements • Design Objectives • Simple to use and easy to set up • Portable and low in maintenance • Functional Requirements • To detect the concentration of methane and CO • Display the gas concentration in ppm to 3 significant digits • An audible alarm • An on/off switch • Battery powered • Design Constraints • Cost effective and simple design • Portable Summary Since toxic elements present in combustion gases are hardly detectable with human senses, the gas detector will help make the residential environment a safer place. It will provide safety and comfort.