Why Scientists Trust Diaphragm Pumps in Environmental Studies
In environmental studies pumps are often used for sample collection or transfer during the analyses. A customer recently brought different environmental studies to our attention, all of which are using one of our pumps as a common component. We chose two air-toxics studies for your further reading.
Analyzing air quality samples; highest standards are required
Our pumps are relied upon in ambient, source and portable devices for environmental sample collection and analysis. The Southwest Indianapolis Air Toxics Study (2010) details a project in which the Indiana Department of Environmental Management (IDEM), the U.S. Environmental Protection Agency (EPA), the City of Indianapolis and a diverse group of stakeholders teamed up to conduct an air-toxics study in Indianapolis, Indiana. This region was identified to be an area of potential risk for cancer risk from air toxics.
A KNF pump (customized from a N 86 standard) was was used to enable the analysis of the total non-methane organic carbon (TNMOC) concentration of ambient air. The U.S. Environmental Protection Agency (EPA) set a National Ambient Air Quality Standard (NAAQS) for the criteria pollutant, ozone. In areas of the country where the standard for ozone is being exceeded, additional measurements of the ambient non–methane organic compound (NMOC) concentration are needed to assist the affected states in developing revised ozone control strategies. Measurements of ambient NMOC are important to the control of volatile organic compounds (VOCs) that are precursors to atmospheric ozone and are the subject of many studies into the negative effects that VOCs have on atmospheric ozone and “the expanding hole in the ozone layer”.
Therefore, a reliable pump was essential for the collection of air samples with potentially harmful toxics. Simultaneously, it was critical for the pump to collect samples in a manner that didn’t change or contaminate the samples. Our KNF pumps, known for their reliability and chemical inertness, are ideally situated for this type of application. Additionally, their extremely high gas tightness allows for the accurate and complete collection of media without the risk of sample loss, dilution, or contamination.
Motor and material options for the micro pump overcame application challenges
Also, in 2001, a study titled In Situ Measurements of Long-Lived Trace Gases in the Lower Stratosphere by Gas Chromatography utilized a KNF pump (referenced as UNMP 830 pump in the article). For this study, a four-channel gas chromatograph measured different air qualities at 70- and 140-second intervals. Air outside an aircraft was delivered to the instrument from an external, variable-speed, two-stage diaphragm pump driven by a brushless 24-V DC motor. The pump was mounted on the aft wall and was controlled by the ACATS-IV onboard computer when the ER-2 aircraft ascended through 87 kPa of atmospheric pressure and continuing to much higher altitudes.
Regarding this second study, there are a few points of interest. First, the usage of the pump was possible through the flexible modular design concept offering a variety of motor and material options. The micro pump was small; however, its footprint wasn’t the only reason it was favored in this challenging design. For example, the pump in this application was taking atmospheric samples at an extremely high altitude, measuring parts per billion (ppb) and parts per trillion (ppt). Expectedly, pump inertness was paramount. Much like in the first study referenced above, environmental analysis customers have come to rely on our pump material options, including PTFE and stainless steel, and on the leak tightness of our pumps.
Additionally, the pump used in this second study was driven by a brushless DC (BLDC) motor, which helped meet the small size mandate. BLDC allows flow rates to be adjusted as needed, helping to extend the lifecycle and reliability of a device. Motor adjustment was also particularly important for this application, because at high elevations, fewer air molecules are available to blow across the pump for cooling. Therefore, the pump faced the risk of overheating. However, the ability to adjust and operate the motor at a lower voltage and speed helped to mitigate this concern. The small and lightweight design of those micro gas pumps even allowed for energy-efficient battery operation.
Also, of note, there was far less ambient pressure at the elevation at which the pump in this study was operating, resulting in less pressure on both the top and undersides of the diaphragm. This condition was certainly not ideal for pump operation, which further added to the difficulty of this application. This, and the other challenges presented by high altitude operation and ppb/ppt detection required a specification-driven, individually tailored pump.
The above studies offer a common theme of our diaphragm pumps being well-suited for environmental sample collection and analysis applications. Here are three more studies for additional reading:
- High-Resolution Measurements of Atmospheric Molecular Hydrogen and its isotopic Composition at the West African Coast of Mauritania (Walter 2013)
- Methane Flux Vertical Gradient Mixing Ratio Measurements in a Tropical Forest (Querine 2011)
- Airborne Gas Chromatography In Situ Measurements Long Lived Species Upper Troposphere Lower Stratosphere (Elkins 1996)
Based on KNF OEM Diaphragm Pumps Used in Multiple Environmental Studies, The Pump Post, 2016