Aspirating Smoke and Gas Detectors
Air sampling monitoring systems detect smoke, H2S, H, CH4, CO & many other components in a wide range of applications
Air sampling monitoring systems detect smoke, H2S, H, CH4, CO & many other components in a wide range of applications
Aspirator systems are used to measure the concentration of specific components in a gas stream flowing through duct using an external instrument. Monitoring for hazardous material releases and acting upon the sample readings can improve operations, ensure safety, and aid in regulatory compliance in a variety of applications such as gas turbine power generation, wastewater treatment plants, and LNG or LPG tankers.
Aspirators are instrument air driven sampling protection systems predominantly used for safety purposes. The sample being measured is pulled under an adjustable vacuum created by an air driven eductor. Flow rates are controlled by an integral needle value with the velocity being indicated on a flow meter. The sample is passed across the sensor and exhausted, along with instrument air, via the exhaust port. If the aspirator is positioned in a “safe” area, it is advisable to pipe the exhaust back to the area it has come from. With external measurement, a sample stream is drawn off from the duct and sent to a remotely-mounted instrument analyzer mounted a safe distance away from the gas stream.
Smoke and gas aspirators are placed in a location outside of the sampling area to maintain accuracy that could be effected by temperature and moisture conditions inside the duct. Self compensating duct probes could be placed in air sampling areas such as in duct in the air intake or exhaust. An aspirator addresses the issues faced by other sampling systems by simultaneously drawing samples across the entire width of the duct to ensure all components are captured. These samples are mixed to maintain proper proportions with respect to their true distribution within the duct
Facility personnel that are unable to remotely monitor for the presence of toxic or combustible gas could enter potentially dangerous areas leading to unsafe working conditions. Examples of applications where aspirators would be useful include: oil & gas; downstream hydrocarbons, power generation; chemical; and water & wastewater. Aspirators commonly are used to monitor for methane, hydrogen, smoke, hydrogen sulfide, carbon monoxide, carbon dioxide, and oxygen depletion in gas streams.
In situ systems are an alternative method of monitoring for hazardous material releases in gas streams. Although in situ measurements offer fast response time, these types of systems do not work well when the gas stream is at a high temperature or is highly corrosive. In these cases, the sensor can foul or fail outright, rendering the measurement invalid. This can be particularly problematic when sensor replacement requires downtime in applications where uninterrupted operation is essential. In situ instruments and analyzers often tend to be expensive due to the requirement for designs with some level of protection from the gas stream.
Documentation and replacement recommendations for discontinued analytical and detection products
