Related Experiment Video
Updated: Aug 10, 2026

VacuSIP, an Improved InEx Method for In Situ Measurement of Particulate and Dissolved Compounds Processed by Active Suspension Feeders
Published on: August 3, 2016
Effect of back-pressure on absorption efficiency of impingers used for air sampling
1Center for Water and Waste Technology, School of Civil & Environmental Engineering, The University of New South Wales, Sydney 2052, Australia. Xinguang.wang@unsw.edu.au
Abstract:
The gas-liquid absorption method, using an impinger as an extracting device, is the most common method for quantifying most gaseous pollutants. The performance of conventional impingers was studied, and several modified impingers were tested. It was found that the sampling efficiency varied from impinger to impinger, which resulted from back-pressure differences between impingers. The back-pressure of ten tested impingers ranged between 160 mm to 520 mm water gage when a 50 mL absorbing solution was used, which caused the ammonia concentration coefficients of variations to be up to 15%. It was also verified that an open bubble distribution tube could be used to eliminate back-pressure variations between impingers. Nearly identical back-pressure (44 +/- 4 mm water gage) could be obtained. This modification can improve measurement repeatability significantly and reduce the coefficient of variation of measurements to 1.2%. With this modification to the impingers, greater accuracy, repeatability and comparison of results can be achieved in the measurement of gaseous pollutants in air.
Related Concept Videos
Measuring Reaction Rates
Le Chatelier's Principle: Changing Volume (Pressure)
Bernoulli's Principle: Applications
Entrainment devices use a high fluid speed to create low pressures and, thus, entrain one fluid into another. Some examples of these devices are given below:
Atomic Absorption Spectroscopy: Interference
Spectral interference occurs when signals from other elements or molecules overlap with the analyte signal, falsely elevating or masking the analyte's absorbance. This interference can be corrected using Zeeman,...
Pressure Relationships in Thoracic Cavity
Breathing Mechanisms
Both intra-alveolar and intrapleural pressures rely on specific lung properties. The ability to breathe—allowing air to enter the lungs during...
Adsorption of Gases on Solids

