There are several known systems to detect the presence and measure the concentration of gases, e.g., combustible gases, and vapors (collectively referred to herein as “gases”). In one such system, the gases are detected based on measuring the rate of heat liberation during catalytic combustion. A combustible gas detector detects and measures combustible gases by burning a gas sample on a catalytic sensor. Catalytic combustion occurs in the sensor on a surface of a heated porous substrate, e.g. silica or alumina that has been impregnated with a catalyst. The resulting increase in temperature of the substrate is proportional to the rate of heat generation during the catalytic combustion and is measured electronically by sensing a resistance change of an imbedded resistance temperature detector (RTD). Details of other types of systems are set forth in the above-identified patent application.
In the field of gas detection/analysis, forced sampling is functionally preferred in contrast to diffusion-type sampling. In forced sampling systems, however, gas velocity variations around the sensor may provoke false sensor readings Generally, two types of pumps for gas sensors have been utilized. There are mechanical pumps which transform electrical power into mechanical movement to transmit the gas sample. Venturi-type pumps are also utilized and which pumps are more robust and reliable. However, venturi-type pumps require a high-pressure compressed air supply which may not always be available. The problem of reliability is oftentimes shifted from the pump to the air compressor. Generally, reliability and cost-effectiveness requirements cannot be met with existing gas sampling pumps, particularly in light of the requirement for ancillary equipment and the substantial number of moving parts.