Gass II-For CEMS and Process Gas Monitoring

The task of a gas sample conditioning system is the removal of particulates, coalescable liquids, and water without loss of analyte gases. Other gas
sample conditioning systems rely on a filter associated with the sample extraction probe to remove all particulates. The GASS-II™ System
includes its own filter for additional protection. Since the filter element in the GASS-II System is sufficiently inert and any trapped particulates absorb a
negligible quantity of gases, filtration has virtually no observable effect on gaseous sample components.

Coalescing liquids can present more of a problem. In addition to water, other compounds that are liquids at room temperature (e.g., sulfuric acid)
may be present in the sample stream. The GASS-II System removes these higher-boiling-point compounds by condensation and subsequent filtration in
its coalescing filter, while water remains in the sample stream until removed in the vapor state by a Nafion® gas dryer.

The GASS-II Systems combines Nafion dryers with a particulate/coalescing filter and all necessary controls to provide a complete gas sample conditioning system. The GASS-II systems can process sample streams with flow rates of up to 25 liters per minute and water levels of up to 75%. Even at these high water levels, a properly configured system will reduce the water content to a dew point well below 0ºC without loss of analyte gases.

Mini-GASS

Perma Pure Mini-GASS sample conditioning systems are designed to prepare hot gas sample streams for high flow, high performance gas monitoring applications. The Mini-GASS system will remove particulates, mists & water vapor from a gas stream without the loss of analyte gasses.

Gas conditioning is accomplished by filtering the sample and then removing water vapor with a Nafion® membrane gas dryer. The dryer is installed downstream of the filter. When the sample enters the dryer it will remove water vapor from the hot sample before it cools down and condenses. This is a distinct advantage over chiller systems, which exposes the sample to condensate in the drying process, allowing water soluble analytes to be lost.

Nafion is not only highly resistant to chemical attack, it also exhibits highly selective absorption. Only compounds that associate chemically with the sulfonic acid group within the Nafion tubing are removed. Gases of environmental interest such as carbon monoxide, carbon dioxide, nitrogen oxides, sulfur dioxide, and hydrogen chloride are totally retained within the sample. With the exception of ammonia, virtually all compounds routinely monitored in a CEMS application are totally retained within the sample stream. Table 1 lists the selectivity of Nafion dryers.

Micro-GASS

The Micro-GASS systems prepare gas samples for analysisby electro-chemical sensor (ECS) analyzers when the sample is hot and wet. These sensors are a very reliable means of detecting the presence of toxic or explosive compounds in a gas stream but inmoisture-saturated samples, sensor life is greatly reduced due to condensation within the cell and subsequent leakage of electrolyte. ECS can also be used with corrosive samples like stack gases, but also suffer reliability problems when the sample humidity is too wet. The Micro-GASS system reduces sample humidity to the ideal range for ECS, typically 30 to 70% R.H., while also removing any dust or dirt particles present.

ACES Ambient Temperature Sampling System for Electro-Chemical Sensors

The Perma Pure ACES™ systems prepare gas samples for analysis by electrochemical sensor (ECS) analyzers when the sample is to humid for analysis but not condensing at ambient temperature.

ECS analyzers suffer reliability problems when the sample is either too wet or too dry. ACES systems reduce sample humidity to the ideal range for ECS (typically 30-70%RH), while also removing any dust or dirt particles present. Incorporating a Perma Pure model MD-070-12P Nafion® membrane dryer, disposable 0.1 micron pre-filter, and integral sample pump, the ACES systems offer full corrosion resistance and very high selectivity, allowing
complex samples to be processed without loss of analyte.