Activated Alumina is an aluminum oxide that is highly porous and exhibits tremendous surface area. It is resistant to thermal shock and abrasion and will not shrink, swell, soften nor disintegrate when immersed in water.
Activated Alumina is available in very smooth, uniform balls of 1/8" (3.2mm), 3/16" (4.8mm) and 1/4" (6.4mm). The uniformity of ball size prevents channeling of the gas flow and minimizes pressure drop.
Activated Charcoal (or Carbon) is a versatile and high capacity adsorbent of hydrocarbons, organics and odors. It is used for the removal of hydrocarbons from liquid and gas streams and the removal of odors. ADCOA stocks both coconut shell based and coal based Activated Charcoal.
Activated Charcoal is commonly used throughout the health physics industry as an air sampling trap. Contaminates adsorbed on the Activated Charcoal can be quantitatively determined and them compared to NIOSH Standards.
Activated Charcoal is used to adsorb trace quantities of contaminates, such as pesticide, from solvents. It is the ideal oil mist removal agent for compressed air.
It is also the preferred adsorbent for the trapping of hydrocarbons in inert gas streams.
ADCOA carries a full line of prepackaged bagged desiccants in a range of bag sizes and filler types. In general, the volume of the container you wish to dry will determine the size of the prepackaged bag required. The type of filler you will need will depend on the application ie: temperature, static Relative Humidity and integrity of the container. We recommend using humidity indicator cards in each desiccant application. The addition of a humidity indicator allows the container to be periodically inspected to insure that the desiccant remains active and the contents safe. As long as the desiccant is in the active condition, the contents of a sealed container will remain free from mildew or corrosion and will be in the same condition as when packaged for shipment or storage.
ADCOA has had long experience in working with the major utilities and power circuit breaker manufacturers in the development and production of SF6 Circuit Breaker Desiccant Bags. These bags are designed to be suspended in the breaker housings to adsorb water vapor and other arc products.
Our Power Circuit Breaker Desiccant Bags are made from self extinguishing, non-dusting Dacron. In most of these bags, we utilize Type 4A Molecular Sieve as the active desiccant. Type 4A has been found to be the preferred desiccant for this application.
Circuit Breaker Desiccants have become a mandatory maintenance item for most breakers in use today. The 4A Molecular Sieve is a synthetically reconstituted alumina silicate which is generated and processed under stringent conditions to establish exact pore dimensions within the lattice of the molecules crystalline structure. These pores are created by removing the water of crystallization from the compound. In its dehydrated state, the Molecular Sieve exhibits a tremendous affinity for water and smaller hydrocarbons, adsorbing over twenty percent of its weight of such contaminates. The incorporation of Type 4A into the static drying system essentially eliminates the danger of arcing caused by gas contamination in the breaker housing.
ADCOA also offers a full range of desiccants for use as a bulk moisture drying bed in the circuit breaker door. These desiccants include Activated Alumina and Silica Gel. We package all of our Circuit Breaker Desiccant Bags in heat-sealed, vapor-proof foil enclosures to prevent contamination of the product prior to use. Packaged in this manner, we guarantee a minimum shelf life to two years.
Molecular Sieves are synthetically produced Zeolites characterized by pores and chrystalline cavities of extremely uniform dimensions. Other adsorbents of commercial importance are typically described as having "pore size ranges". The pore sizes of these adsorbents can vary widely on the face of the same particle. Molecular Sieves will not have this variation in pore size.
An important adsorption characteristic of Molecular Sieve is its ability to continue the adsorption process at temperatures which would cause other desiccants to desorb trapped contaminate molecules. In a gas drying system, water will continue to be adsorbed even though the process temperature may be in excess of 300°F. It must be understood, however, that the adsorption capacity of all desiccants is negatively affected by temperatures in excel of 100°F. Molecular Sieves retain their ability to adsorb water molecules over a much wider spectrum of temperatures than other desiccant materials.
Molecular Sieves have a much higher equilibrium capacity for water vapor under very low humidity conditions and are very effective in reducing the water vapor content of gases in the parts per million range. Molecular Sieves are ceramic-appearing pellets of balls in diameters of 1/16" or 1/8" and do not change size or shape upon reaching saturation. Molecular Sieves have the lowest dusting factor of any commercially available desiccant.
ADCOA Moisture-Indicating Molecular Sieves have the same high capacity adsorption characteristics as our non-indicting Molecular Sieves. In the active condition, Moisture-Indicating Molecular Sieves are bright blue in color. As the desiccant adsorbs moisture and the relative humidity approaches 10%, it turns a lighter blue color. As the desiccant progresses towards saturation the color turns to buff. At this point, the Molecular Sieve should be replaced .
Silica Gel is the most widely known and most versatile of all desiccant products. The Silica Gel offered by ADCOA is of the highest purity (99.7+% Elemental silica). Chemical purity is of great importance as the presence of metallic impurities can impede reaction processes or cause corrosion. An important factor that affects the adsorption efficiency of desiccants is the surface. For example, Grade 03 Silica Gel has a surface area of nearly 900 square meters per gram. To visualize this phenomenon, we can say a teaspoon of Silica Gel has an internal area equivalent to a football field... including the two end zones. All of this area is available for the removal of impurities or moisture. Silica Gel has a high equilibrium capacity. Although this capacity hardly varies with changes in temperature, it increases greatly when the relative humidty is elevated. Silica Gel will selectively adsorb compounds of differing molecular weights. In the vapor phase, compounds of high polarity are more readily adsorbed. The relative adsorbability for several compounds is as follows:
Water (most readily adsorbed)
Paraffins (least readily adsorbed).
Dynamic adsorption is the process by which the Silica Gel removes an impurity (e.g.: water) from a continuously flowing gas stream. The use of Silica Gel in a drying column can produce exit gas with a dew point of -100°F. The adsorption process is easily reversed by a number of methods. In general, these methods require that the condition surrounding the adsorbent are changed to those corresponding to a very low equilibrium capacity. Thermal swing is the most commonly utilized process by which Silica Gel is regenerated. By increasing the temperature of the Silica Gel Bed, the adsorption capacity is effectively reduced. As the adsorbate leaves the Silica Gel surface, it is easily removed with a purge gas.
Granular Moisture Indicating
Beaded Moisture Indicating
The decision to use a granular or beaded type of Silica Gel depends upon your application. A few of the advantages of each type are listed below:
Container Dri® II is a line of specially designed cargo desiccants aimed at protecting cargo during shipping by aggresively absorbing moisture from the air. In doing so, Container Dri® II reduces dew point temperature (the temperature at which condensation begins to form, causing “container rain”), keeping cargo safe and dry. The Container Dri® II line includes several configurations to best fit different needs and modes of transport.
Humidity Indicator Cards are simple "hygrometers" that rely upon the reaction of a chemical agent impregnated on each card with water in the surrounding atmosphere to show within a narrow range of accuracy the prevailing Relative Humidity. Humidity Indicator Cards can be used in conjunction with a Desiccant in order to assure that the Relative Humidity within a package, compartment, electrical panel, vessel, instrumentation cabinet or sealed container never approaches levels that would cause corrosion. condensation or equipment failure. The "Active" (Blue) condition of the card can be restored many times with the application of fresh desiccant when card spots become "Saturated" (Pink). These cards are accurate within the range of plus or minus 2.5% RH.