Portable Gas Detector

1
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

• 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.