Ammonia is a colorless gas that has a bevy of uses in industry such as a compound used for the production of fertilizers and as a refrigerant. There are a few states and compounds of Ammonia that are common including liquid Ammonia, Anhydrous Ammonia, and Ammonium Hydroxide. Although it has many uses, Ammonia is intrinsically dangerous because it is flammable and can cause severe irritation if the user is exposed. Careful selection of materials of construction is required to sustain a stable Ammonia system.
Tree logs are pulped by using "white liquor" (consisting primarily of sodium hydroxide and sodium sulfide), process water, heat, and pressure to separate wood chips into lignin and cellulose fibers. Wood chips contain approximately 50% water and 50% wood by weight. Process water and white liquor are necessary to create "black liquor". Black liquor is created when the process water is drained off and recycled, leaving lignin, other organic chemicals, and inorganic chemicals behind. Water is removed until the black liquor has a viscosity similar to molasses, and has a composition of 60 percent solids by volume. At this stage, a small amount of diesel fuel is added to the black liquor to produce a low cost fuel mixture to burn in plant boilers. This helps the process become more energy efficient. The black liquor burn is not 100% efficient, and a residue called "green liquor" remains. Green liquor is further chemically treated, and recycled to the start of the process to become white liquor.
Boiler blowdown is a term that describes water that is purged to prevent contaminants like scale and solids from building up in a boiler. These contaminants build up over time, which reduces the efficiency of the boiler and can prevent the boiler from operating properly. Makeup water is the water added to replenish the boiler system after the blowdown is purged. Makeup water is usually preheated in a heat exchanger prior to entering the make up tank to 175-190°F. This helps the water to blend with the hot returning condensate in the make up tank without flashing. Flashing is the sudden, violent change of liquid water to water vapor because of a pressure drop. Flashing could cause water hammer and potential damage to the level control system and piping.
Caustics are compounds that corrode certain materials that they come in contact with. Two common caustics are Sodium Hydroxide (Caustic Soda) and Potassium Hydroxide (Caustic Potash). These chemicals are dangerous: skin contact may produce severe burns and inhalation could cause damage to the respiratory system. Knowing these facts, careful selection of materials of construction and characteristics of valves is imperative to sustain a safe, stable caustic system.
Chlorine is highly reactive and toxic in all concentrations. Due to these facts, knowing more about the system that the chlorine will be present in is vital. Chlorine service can be divided into two categories: wet systems (greater than 150 ppm of water) and dry systems (less than 150 ppm of water). Knowing whether the Chlorine system is wet or dry determines what materials of construction will be selected to best perform in the system.
Ethanol is produced in a four step process. First, the feedsock is milled and water, enzymes, and other components are added to convert the feedstock to glucose sugar. Mash is created from this mixture. Next, yeast is then added to the mash to start the fermentation process. After fermentation is complete, beer and distiller grains are left and other solids are removed. The distiller grains are then removed from the water/ethanol mixture and sold, and the water/ethanol mixture is sent to distillation. Distillation uses heat and the volatility of water and ethanol to achieve a 95% ethanol mixture. Molecular sieves are then used to further separate the mixture to become about a 98.5% ethanol mixture. Denaturing of the high concentration of ethanol by adding gasoline helps producers avoid liquor taxation.
Ethylene Oxide is very flammable and explosive. It also is a carcinogen and could cause other major health problems such as nerve damage in low concentrations. Ethylene Oxide is also known to decompose at higher temperatures (842-1040°F) and this decomposition could produce runaway reactions. Although there are inherent dangers that are present for the production and handling of this molecule, Ethylene Oxide is very useful in production of detergents, cosmetics, and the sterilization of surgical equipment. Careful selection of materials of construction and characteristics of valves is imperative to sustain a safe, stable Ethylene Oxide system.
Hydrogen Peroxide is a colorless liquid that can be used for things such as disinfection and bleaching. Handled correctly, Hydrogen Peroxide can be safe. Handled incorrectly, however, it can be explosive and dangerous. A very clean and safe system is required for Hydrogen Peroxide service because of the dangers of this molecule. With this in mind, careful selection of materials of construction and makeup of Hydrogen Peroxide service valves is imperative. It is also important to know whether the system will have diluted concentrations of Hydrogen Peroxide (less than 50%) or higher concentrations (greater than 50%), and the temperature of the application.
Natural Gas is a colorless, odorless, and non-toxic gas that primarily consists of Methane and other heavier hydrocarbons like ethane, propane, etc. Other components of Natural Gas can include Nitrogen, Carbon Dioxide, Water, and Hydrogen Sulfide. Natural gas burns readily with air when between its lower flammability limit in air (about 4% concentration in air) and upper flammability limit in air (about 15% concentration in air). When Natural Gas contains a set concentration of Hydrogen Sulfide, it is commonly referred to as "Sour" Natural Gas, while if it is below that set concentration it is commonly referred to as "Sweet" Natural Gas. This concentration varies between states/countries. Hydrogen Sulfide in low concentrations can attack soft materials such as Nitrile Buna Rubber (NBR). Knowing these facts, careful selection of materials of construction for pneumatic actuators is imperative for a safe, stable Natural Gas system.
Oxygen is an element that exists as diatomic molecule (O2) in most conditions. Although Oxygen is necessary for life, it is very reactive at certain pressures and temperatures. Reactions with Oxygen can be minor like the production of rust, but they can also be major culminating into an explosion. Knowing these facts, careful selection of materials of construction and characteristics of valves is imperative to sustain a safe, stable Oxygen Gas system.
Please consult A-T Controls for seat material selection for your unique applications. These parameters are guidelines, and customers are responsible for materials of construction being compatible with their valve application. ANSI/ASME B16.34 should be considered when selecting valve materials of construction (for example, ASTM A216 Grade WCB is not recommended in services above 797°F). Please note other materials present in the valve will be affected by higher temperatures/pressures, such as o-rings, joint gaskets, and pyramidal stem seals. MAST (Maximum Allowable Stem Torque) should be considered when using seat materials that require added torque. Frequency of operation is also a factor that should be investigated when selecting a seat material. Pressure vs. Temperature charts for individual valves series should also be considered when selecting the correct seat material. Applications that involve process media that is prone to thermal expansion (Ammonia, water/steam, Chlorine, etc.) require a vented ball to improve seat durability. Room temperature is defined as 72°F.
Steam is an invisible gas unless condensed in cooler air. Steam has many industrial uses like heating and cooling applications and because of its expanding nature, for generating power. Forms of steam include saturated, superheated, and supercritical. Caution needs to be used when selecting valves for steam service to assure the application temperature and pressure are met with the right valve body and valve trim materials.
In wine making, temperature control is a critical factor in two key areas. First, control of fermentation temperature, and second the wine is stored at a constant temperature after fermentation is complete until bottling. One of the most effective methods of tank temperature control is employing a glycol system. Other methods include Ammonia. Please contact A-T Controls for Ammonia application details. The use of a glycol temperature control system is discussed below.
A vacuum is defined as pressure below atmospheric pressure at sea level. Atmospheric pressure is usually defined as about 14.70 psia (pounds per square inch absolute), 760 mm Hg (Mercury) absolute, 29.92 inches Hg absolute, or 760 torr.