Pumps, Dryers, and Filters

Perma Pure MD-Series gas dryers are single tube Nafion® dryers designed for high performance gas monitoring

applications. These dryers can be used to dry a sample to as low as –45° C without removing sample analytes. The
Perma Pure dryers consist of a single Nafion tube housed within a stainless steel or flexible plastic tube shell.
Sample gas flows within the Nafion tube while water vapor absorbs into the Nafion membrane tube walls and is
removed. A dry purge gas within the shell that flows countercurrent to the sample carries moisture permeating the
membrane away. Purge gas should be instrument quality (-40° C dew point) air or nitrogen flowing at two to three
times the sample flow rate.

Perma Pure offers three MD dryer product lines: MD-050, MD-070, and MD-110 (050, 070, and 110 correspond to a
Nafion tube outside diameter of 0.050", 0.070", and 0.110" respectively). Dryers are available in lengths of 12", 24",
48", 72", 96" and 144", depending on the dryness required. Each model is available in stainless steel (S),
fluorocarbon (F), and polypropylene (P) versions to accommodate corrosion resistance and temperature
requirements.

MD-050 dryers are used for up to 200 cc/min. gas flow rates. MD-070 and MD-110 dryers are both suitable for flows
of up to 2 liters per minute. These two dryers offer approximately the same drying performance; select the MD-110
when pressure drop is a concern and the MD-070 when minimizing dead volume

Perma Pure PD-Series™ gas dryers are multi-tube Nafion dryers designed for high flow, high performance gas drying applications. These dryers can be

used to dry to -45°C without removing other compounds. PD-Series dryers consists of a bundle of 0.030" O.D. Nafion tubes housed within a single large tube shell. Feed gas flows within the Nafion tubes while water vapor absorbs into the tubular membrane walls and is removed. Moisture permeating the tubing is carried away by a dry purge gas within the shell that flows countercurrent to the feed. Purge gas should be instrument quality air (-40°C dew point) or nitrogen flowing at two to three times the sample flow rate. Perma Pure offers three PD dryer models: PD-50T, composed of 50 tubes; PD-100T (100 tubes); and PD-200T (200 tubes). Each dryer is offered in lengths of 12", 24", 48" and 72". Dryers are available in the following configurations: polypropylene (PP) (50T-12" only), polypropylene fittings with stainless steel shell (PS), Kynar (fluorocarbon) fittings with stainless steel or anodized aluminum shell (KS,KA), and stainless steel fittings with stainless steel or anodized aluminum shell (SS,SA). For special applications, dryers are also available with flexible rubber shells or corrugated stainless steel shells.

Applications for PD-Series gas dryers include gas sample conditioning for continuous emissions and process monitoring. In these applications, sample gases flowing through the Nafion tubing are dried without removing any of the sample analytes. PD-Series dryers are also used as moisture exchangers in fuel cell applications. Fuel cell exhaust gases transfer their moisture and heat to the dry inlet gases (primarily hydrogen). Finally, PD-Series gas dryers can be used in small scale process applications. Process applications take advantage of one or more of the unique properties of Nafion: highly efficient and selective moisture exchange, ion exchange capabilities, and extreme corrosion resistance. The Performance curves to the left are based upon an inlet dew point of 20°C. For conditions higher than ambient temperature, it is assumed that the first half of the dryer will be used to bring the dew point down to ambient. For this reason, read the value of the next shorter dryer. For example, a stream with an initial dew point of 50°C, flowing at 2
lpm; a PD-50T-24 should yield an outlet dew point of -6°C, the performance of the 12" unit.

ME™-Series moisture exchangers from Perma Pure are ideal for both drying and humidifying gas streams. This device uses Nafion® membrane tubing technology to transfer water to or from a gas stream. In either application, ME-Series moisture exchangers will act to achieve equilibrium between the gas inside the tubing and the surrounding atmosphere. This is done without loss of analytes and with no utility requirements.

In drying applications, ME-Series moisture exchangers transfer water vapor from a wet gas stream into the surrounding atmosphere. Drying is complete when the sample humidity level is equal to the ambient humidity level. Since drying proceeds as a First Order kinetic reaction, this level can be reached extremely quickly, usually within 100 to 200 milliseconds. This behavior makes the dryer ideal for applications involving a very humid sample at room temperature. Sample humidity can easily be reduced to as low as 10% of its original moisture content with only a short length of Nafion tubing. ME-Series dryers are used to prevent condensation in a variety of gas monitoring equipment. For humidification, the ME-Series will transfer water vapor from the atmosphere to a dry gas flowing within the tubing. Once again, this process occurs in a fraction of a second and is very stable and repeatable under constant operating conditions. A common application is to humidify calibration gases, which allows calibration of analyzers at humidity levels equal to those seen in samples, providing a more consistent calibration/sample baseline.

For applications requiring portability, the DM™-Series dryer is ideal. No pumps or purge gases are required, yet the cigarette pack-sized dryer removes water vapor from a flowing gas stream for hours, leaving other components in the gas stream unaffected.

The dryer can be reused repeatedly and can be recharged in moments by replacing its desiccant.

DM (Desiccant/Membrane) gas dryers combine the selectivity of Nafion® gas dryers with the simplicity of desiccant canister dryers. Gaseous sample flowing through the dryer contacts only Nafion tubing, which very selectively absorbs water vapor from the gas while quantitatively retaining the remaining sample components in the gas stream. Typically water passes through the Nafion tubing wall and is carried away by a dry purge gas; instead, in DM-Series dryers, desiccant packed around the tubing provides a dry purge environment. No power or other utilities are required.

Two DM dryer models are available. The DM-060-24 accepts a flow rate of up to 500 mL/min., while the DM-110-24 is best suited for flows of up to one liter per minute. The DM-060 contains approximately 2.5 ounces of molecular sieve, while the DM-110 contains approximately 5.5 ounces.

THE WATER PROBLEM
As a byproduct of respiration, water is present in breath as an unmeasured and undesirable interferent. Exhaled air is saturated with water vapor. Unless it is removed prior to analysis, this water vapor interferes with the measurement of the breath gases of interest in several ways:

When condensation collects in small quantities in the sample lines or measurement cells of gas analyzers, the precision and accuracy of the analysis degrades. As the quantity of condensation increases, the measurement is interrupted entirely when the water occludes a sample line, infrared cell window, or electrochemical membrane. In some analyzers such as paramagnetic oxygen analyzers and mass spectrometers, the detector may suffer
permanent damage when exposed to water. Water has numerous broad absorption bands in the infrared region of the spectrum. These overlap spectral lines used in infrared analyzers to detect carbon dioxide (see Figure #1).

Although methods exist to subtract this background signal, removal of the water vapor prior to analysis improves the accuracy and precision of the carbon dioxide measurement by substantially reducing this interference.
If gas analyzers are calibrated at low humidity and patients are monitored at saturated humidity, the elevated partial pressure of water vapor yields an inaccurate analysis unless a correction is applied to the results. Removal of the water vapor prior to analysis eliminates this interference.
Selectively removing water vapor from breath samples without altering the concentration of analyte gases is consequently a key step in obtaining accurate, precise, and reliable results from medical gas analyzers.

DRYING BREATH SAMPLES
Since breath is saturated with water vapor, liquid water will begin to condense as soon as the temperature of the breath begins to fall. Various devices are used to remove this condensation from the expired breath sample, such as hydrophobic filters or unfiltered and filtered water traps.
Although these devices remove liquid water, they do not remove water vapor. They also add dead volume to the sample circuit, and must be drained or replaced when filled with water. Since water vapor is not removed by any of these devices, the problems may be reduced but are not eliminated. Devices typically used to remove water vapor are inappropriate for this application because they are not sufficiently selective. For example, desiccants will
remove water vapor from air, but they also absorb or desorb analyte gases, particularly carbon dioxide. Permeation membranes remove analyte gases in addition to water vapor and also require long exposure times to remove the water. Fortunately a device to selectively remove water vapor is available. ME Gas Dryers™ constructed of Nafion® are ideal for removal of water vapor from breath. ME Gas Dryers remove up to 90% of the water vapor while
leaving the oxygen, carbon dioxide, and anesthetic gases unaffected.

NAFION - THE PERFECT DRYING MATERIAL
Nafion is a copolymer of tetrafluoroethylene (Teflon®) and perfluoro 3,6dioxa-4-methyl-7-octene-sulfonic acid (see Figure 2).

Nafion shares the high chemical resistivity of Teflon, but the presence of its exposed sulfonic acid groups confers unusual properties. The sulfonic acid has a very high water-of-hydration, absorbing 13 molecules of water for every sulfonic acid group in the polymer; consequently, Nafion absorbs 22% by weight of water.
Unlike membrane permeation, which is a relatively slow process, water is absorbed by Nafion as water-of-hydration. Since this absorption proceeds as a first order kinetic reaction, equilibrium is reached very quickly, removing water from the sample in only 100 to 200 milliseconds. Water passes through the Nafion membrane and evaporates into the surrounding air until equilibrium with the external humidity is reached in a continuous process called perevaporation.
Exposing a breath sample to liquid water in traps or to desiccants or permeation membranes invites exchange of analyte gases with the water or the absorbant, changing the results of the analysis. Since Nafion is totally inert to the analyte gases, it is extremely selective; it removes only the water vapor, leaving the analyte gases otherwise unaffected.

ME-SERIES DISPOSABLE GAS DRYERS
Gas Dryers exploit this unusual property of Nafion to produce a device to remove water vapor from a flowing gas. They are constructed of Nafion tubing surrounded by a polypropylene monofilament braid (1) for mechanical strength and for protection from skin oils and other contaminants. This design produces a rugged sample line that rapidly removes water vapor from breath, but is otherwise quite inert. Water is continuously passed to the surrounding
atmosphere while the remainder of the breath passes unchanged to the analyzer.
The patented ME Gas Dryers have injection-molded luer fittings (2,3) fused to the protective braid (4) for a gas-tight seal. No adhesives or solvent bonding processes are required. The dryers are available as a low-cost disposable item; if desired, an inert sampling line can be attached for connection to medical gas analyzers. Sampling tees and low dead-volume hydrophobic filters to remove solids from the sample may also be packaged with the dryers. The dryers and lines are produced in a variety of diameters to accommodate a wide range of flow rates.

INVESTMENT IN RELIABLE RESULTS
The modern medical gas analyzer is designed to minimize problems associated with water entry into the system; nevertheless, accumulation of water inside the system remains the primary cause of analyzer failure.
Substitution of a disposable ME Gas Dryer sample line for the nondrying sample line between the patient and the analyzer reduces the humidity of the sample to room levels before the sample reaches the analyzer, virtually eliminating these problems. Failure of the analyzer at a critical moment may be life-threatening to the patient. The benefits of reduced analyzer downtime and maintenance costs - plus improved accuracy and precision when water interference's are removed - far outweigh the modest dryer cost to the patient.

PROVEN TECHNOLOGY
Perma Pure Inc. developed the first Nafion gas dryers more than twenty years ago. The dryers are used throughout the world for sample conditioning prior to analysis by scientific and medical instrumentation. Typical medical applications include:

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.

The sample entering the system may have traveled only a short distance from the sampling point and remain very hot, or it may have traveled a considerable distance through heated lines and be near the operating temperature of the GASS-II System. Three separate temperature zones are maintained within the GASS-II enclosure in order to accept virtually any sample and to provide optimal conditions for each phase of the
sample treatment.

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.

Micro-GASS units offers full corrosion resistance and very high selectivity, so complex samples can be processed without loss of analyte gases. Nafion dryer technology is the driving force behind this system. Operating as a self-contained unit, the Micro-GASS incorporates a built-in sample pump to draw the sample gas through a 0.1µ filter then into a MD-Series™ Nafion gas dryer where water vapor is absorbed into and through the membrane walls. The dried sample then flows to the sensor where the measurement is made. After exhausting from the ECS, the gas passes through a needle valve and expands, causing a reduction in vapor pressure. It then reenters the dryer to be used as a purge gas. Because the purge gas is generated from the exhaust stream of the sensor, it makes the Micro-GASS a self-regenerating and transportable conditioning system, relying only on a power source. Typical applications for the Micro-GASS sample conditioning system include monitoring of boiler and burner efficiencies.

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.

The ACES system is very easy to operate. Simply connect the ECS diffusion cell to the sample outlet of the ACES unit, then connect the sampling cell outlet back to the sample return port on the ACES. The ACES pump continuously draws the sample through the ECS, providing quick response time.

System power is supplied by a standard 120 or 240VAC circuit. If electrical power is not available or the system is to be installed in a hazardous area, an air driven version is also available. All models are housed in NEMA 3R housings that measure 12"W x 7"H x 6"D and has a clear hinged cover for convenient inspection of the flow rate and disposable filter. No tools are required for replacement of the filter or panel mounted fuse. Vertical installation is required for proper operation of the flowmeter. Wall mounting feet are supplied with the unit.

#121 FF-250 Coalescing Filters
#122 FB-Series Inertial Bypass Filters
#123 FF-Series Filter
#130 HD-Series Compact Heatless Desiccant Dryers
#140 Portable Zero-Air Generators
#150 Ammonia Scrubbers
#160 Hydrogen Purification Systems
#170 Eductors
please contact us for more information on these accessories

Our 800 series liquid "Free Flow" filter housings are ideal for a variety of liquid purification solutions. The Free Flow housings are available in stainless

steel (SS), cast iron (C), or brass with a 304 stainless steel bowl (B). Port sizes range from 1/4" NPT up to 1 1/2" NPT and 2" NPT. The larger port sizes are unique to UFS. Our competitors only offer these types of filters up to 1" and then "force" you into a multi-element vessel. The larger port sizes allow greater flexibility in providing the correct filter for the application. We can also provide these housings with gauges, flanges or sight glass columns.

1. One piece bowl construction for quick and spill free element service.
2. Extra bottom reservoir capacity for sediment deposit collection.

Choose from disposable spun polypropylene or pleated elements, to our cost effective, re-cleanable, pleated stainless steel elements to cover all your
requirements. Our elements range from 500 micron efficiency down to sub-micronic. With our housing and element choices these flexible filters can
be used to process water, coolant, paint, and petro-chemical filtration.

Base Model	Maximum Flow Rate
816	5 GPM
820	10 GPM
895	20 GPM
897	30 GPM

Sampling Pumps

Dia-Vac® Gaseous Sampling Pumps
High quality Diaphragm Pumps and Compressors
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Explosion Proof Diaphragm Pumps and Compressors
Air Driven Diaphragm Pumps and Compressors
Heated Head diaphragm Pumps and Compressors
Micro Dia-Vac® Pumps
Standard Dia-Vac® Pumps
Mini Dia-Vac® Pumps
Specialty Dia-Vac® Pumps
Explosion Proof Dia-Vac Pumps
Heated Head Dia-Vac Pumps
Double Diaphragm Dia-Vac pumps
Air Driven Dia-Vac Pumps

Environmental Analytical Systems
286 Mask Island Drive
Barry's Bay, Ontario, Canada K0J 1B0

Phone: 613 756 0101
Toll Free (Canada only): 1 800 427 8591
Fax: 613 756 0909
email: info@enviro-analytical.com