MAC Instruments is a leading provider of high-temperature humidity measurement instruments for industries around the world. Our moisture analyzers and steam flow rate meters exhibit exceptionally high sensitivity to moisture content, for instant results that you can rely on. We have engineered a broad range of analyzers and meters to meet the needs of a variety of applications, including food processing, oil and gas refineries, mining activities, and metal treatment, among many others. Our instruments are easy to install and include a user-friendly interface for efficient and reliable operation.

We’ve compiled the following glossary to assist our customers in understanding the common terminology surrounding metrology instrumentation.

Glossary of Terms

Absolute humidity  The measurement of the amount of water vapor within a given amount of air at a specific temperature. Air can contain more water at higher temperatures, so absolute humidity is measured based on specific air temperature. Absolute humidity is determined by dividing the mass of water vapor in the air by the mass of dry air in a specific volume of air at a particular temperature. This measurement is typically conveyed in grams of water vapor per cubic meter of air (g/m3).

Annealing  Annealing is a treatment process often used in metal and glass manufacturing to enhance material ductility. It is often performed on materials that have already undergone cold forming or hardening processes. Annealing involves heating the material to a temperature below the melting point to encourage reformation of the crystalline structure and reduce microstructure dislocations. This realignment reduces the material’s hardness and increases its formability, making it less likely to crack or break under strain from normal operations or additional fabrication processes.

Basic Oxygen Furnace (BOF)  A basic oxygen furnace (BOF) is one of the most common methods used to manufacture crude steel. The furnace uses blown oxygen on molten iron and steel to create an exothermic reaction, which oxidizes impurities in the steel. The amount of oxygen blown onto the molten steel can be varied to modify the carbon content as needed.

Dew point – The dew point is the temperature at which the relative humidity of the air reaches 100%. Once air is cooled to a temperature below the dew point, the moisture in the air will be released in the form of condensation. The dew point is determined based on the specific moisture concentration and dew point temperature at a given time and will change relative to these conditions. The dew point is affected by atmospheric pressure and altitude, and is therefore not an absolute scale.

Drying  Drying is the removal of moisture from a solid material through evaporation. The process can be affected through the use of heaters, gas streams, vacuums, and heated drums. It is often used for mass production of food products, fabrication of non-food products such as timber, paper, and detergents, and solid waste removal in industrial sanitation processes.

Flue gas  Flue gas consists of mixed gases produced through combustion and released through a smoke flue. It typically contains nitrogen, carbon dioxide, carbon monoxide, and water vapor, among other gases. Systems can be put in place to filter and recycle some flue gases for reuse in industrial processes.

Humidity ratio  The humidity ratio of air is a measurement of the amount of water vapor in a given volume of air. It is calculated by determining the percent of moisture by volume in the air and the specific mixture of gases present in the air. The humidity ratio (HR) will be measured differently based on the average molecular weight of the gases present and can be determined by multiplying the average molecular weight (MW) of the air by the percentage of moisture by volume (%MV), as follows: HR = MW x %MV / (100-%MV).

Humidity sensor  A humidity sensor is a sensitive instrument used to measure and report air moisture and temperature, enabling the accurate calculation of relative humidity.

Moisture analysis  A broad term for methods used to determine the moisture content of solids, liquids, and gases. The measurement of moisture levels is important for product quality in a variety of applications, including food processing, pharmaceutical production, metal and plastic manufacturing, power plant operations, oil and gas transport, and semiconductor operations, among many others.

Moisture analyzer  An instrument used to obtain moisture measurements in solid, liquid, and gas materials and analyze them for enhanced moisture control. A wide variety of moisture analyzers have been designed to meet the needs of various applications. Due to their ease of use and real-time transfer of information, automated moisture analyzers are becoming more common in numerous industrial settings.

Partial pressure  The pressure exerted by a particular gas or combination of gases within a greater gas mixture. It can be used to determine the total pressure of a gas mixture by adding together the partial pressures of the constituent gases.

Relative humidity (RH)  A measurement of the amount of moisture in the air at a specific temperature and pressure. It is expressed as a percentage of the maximum amount of water vapor that can occur at that temperature and pressure.

Saturation pressure (Ps)  The specific partial pressure expressed by a gas, such as water vapor, when it has reached 100% equilibrium with its liquid state. Measurement of the saturation pressure indicates the evaporation rate of the liquid at a specific temperature and pressure.

Specific humidity  The ratio of water vapor in a particular sample of air to the total mass of the mixture of dry air and water vapor present in that sample. In order to determine the specific humidity of a sample, the percent moisture by volume of the air must be known.

Stack  The means by which exhaust products are emitted from manufacturing facilities into the atmosphere, where they can be safely dispersed over a large area. Types of stacks include chimneys, flues, and boiler exhaust pipes. Stacks are typically engineered to meet the particular needs of the application for which they are being used.

Stack emission monitoring  The process by which the exhaust released through stacks and emissions systems is measured for pollutant concentration. These measurements are compared with industrial and governmental regulations to ensure that emissions are within allowable limits.

Starch gelatinization  The process by which starch combines with water to create a gelatinous substance. During the process, starch particles are submerged in water and exposed to heat, causing the starch to absorb the water and swell into a clear, viscous liquid. The resultant gel is a common ingredient in food products, where it serves as a thickener and texturizer.

Steam  Water that has been converted into its gaseous form through the application of heat above water’s boiling point.

Steam flow  The collection and analysis of the pressure and flow of steam produced from water heated by a power source such as fossil fuel combustion, nuclear power, solar energy, or geothermal energy. Measurement of steam flow allows for accurate calibration and efficient use of energy resources for power generation.

Surface treatment  Surface treatment refers to application of heat, pressure, or chemical treatment to the surface of a metal component to enhance certain characteristics. The treatment process improves the ability of the metal to successfully undergo finishing processes such as painting, coating, and printing. In addition, surface treatments can enhance corrosion resistance, temperature resistance, and abrasion resistance.

Measurement Instruments From MAC Instruments

MAC Instruments is pleased to provide superior humidity measurement instruments for a variety of industries and applications. To learn more about our quality instrumentation and services, please contact us.