Dispersion Modeling uses mathematical formulations to characterize the atmospheric processes that disperse a pollutant emitted by a source. It is used to predict concentrations at selected downwind receptor locations based on emissions and meteorological input. The air quality models are used to determine compliance with National Ambient Air Quality Standards (NAAQS), and other regulatory requirements such as New Source Review (NSR) and Prevention of Significant Deterioration (PSD) regulations. These models are addressed in Appendix A of EPA's Guideline on air quality models to provide consistency and equity in the use of modeling within the air quality management system. These guidelines are periodically revised to ensure that new model developments or expanded regulatory requirements are incorporated. It serves to assist in the design of effective control strategies to reduce emissions of harmful air pollutants.

Displacement transducer is a transducer used for measuring relatively small amounts of movement in the vertical or horizontal plane. The amount of movement is detected by means of change in an electrical signal caused by the movement of an iron core within a coil. It can measure either linear displacement or angular displacement. It can also be classified according to the principle of transduction on which it is based.

Displacer actuated external cage switches are external cage units that utilize a single switch mechanism for level alarm or control functions in higher-pressure applications. Liquid level movement changes the buoyancy force on a displacer suspended from a range spring. The force change on the spring causes it to expand or contract, moving an attraction sleeve into or out of the field of the switch magnet, actuating the switch. It is used in hydraulic accumulators, natural gas receivers and separators applications.

Displacer actuated level controls for boiler feed systems is a displacer actuated level controls that provide output signals in direct proportion to changes in liquid level. As the buoyancy force on a displacer changes with liquid level movement, a range spring supporting the displacer extends or compresses, moving a magnetic ball. A magnet carriage within the controller head follows the ball producing a change in output. It is applicable in feed water and steam drum applications.

Displacer Type Level Switches offer the industrial user a wide choice of alarm and control configurations. These units utilize a simple buoyancy principle. It is well suited for simple or complex applications such as high level alarm or control of multiple pumps and alarms.