DOWESTON has compiled and written definitions of several industry terms. This list is intended to be a glossary to help you better understand the elements of our industry. Process instruments are used in a very wide range of applications wherever measurement of media flowing in a stream or stored in containers or tanks is required. Many of these terms will help you understand the techniques used in this type of measurement.

Accuracy

The accuracy of a flow meter is the maximum positive or negative deviation between the meter's indicated value and the true value of the flow rate or the total value of the flow rate. It is the interval between the true value of a measured quantity that can be expected and the stated probability. Accuracy can also be called uncertainty. Accuracy includes combined errors due to linearity, hysteria, and repeatability. Accuracy can be expressed as a percentage of span or full scale, as a percentage of rate, or as a percentage of an upper or upper limit value. It is important to understand the difference between the stated values.

Back pressure

Back Pressure - Refers to the pressure rather than the required flow of gas in a given pipe diameter. Any condition where the pressure in the system is greater than the supply pressure. Back pressure is caused by obstructions in the pipe, pipe direction or direction, pipe surface and pipe type, and tight bends. The term back pressure is misleading when pressure is maintained and causes flow to flow in the same direction due to air resistance, friction between molecules, but flow is reduced due to resistance. Back pressure is often confused with pressure drop. Back pressure facilitates the release of vapor from a liquid and is a function of the liquid flow tube system head. This condition is often called cavalier.

flow meter

Flow meters measure continuous flow by detecting thermal changes in the medium as it flows through the sensor. For reference, thermal flow meters are commonly used in air conditioning, dust collection, energy conservation systems, potable/non-potable water, sulfuric acid, and ventilation monitoring.

Flow Switch

A flow switch that measures flow by detecting thermal changes in the medium as it flows through the sensor. Thermal flow switches are used in chemical feed systems, cold water feeds, combustion cooling systems, damping regulators, for pump protection and ventilation.

Cavitation

If a liquid enters the meter at a pressure close to vapor pressure, a pressure drop in the meter will cause the liquid to gas. If, as the pressure is restored, the gas pressure rises above the vapor pressure again, the bubbles will burst, causing cavitation. Plating and vaccination can damage many piping systems and many types of flow meters.

Degree

Properties of liquids expressed as weight or mass per unit volume. Liquid density is generally a function of temperature. Gas and vapor density changes with changes in temperature and pressure. For example, water has a density of 62.34 pounds per cubic foot and is 60o F. Density is 60.13 pounds per cubic foot at 200o

F. [TOP]

EMI/RFI effects

EMI/RFI Effects - Electromagnetic interference (EMI), also known as radio frequency interference (RFI), occurs when interference in the radio spectrum is caused by external interference, affecting circuits through electrostatic coupling or conduction. Electromagnetic emissions can cause adverse reactions or degradation in the performance of electrical equipment. Typically produced by welders, motor starters, VF drives, radios, resulting in a proliferation of analog instrument signals. Shielding and line filters can reduce these effects.

Meter

A process instrument that measures the continuous flow of a medium through a pipe or other container. The medium being measured is usually gas, liquid or mud. There are many technologies available for flow measurement, some of which include thermal, mass, positive displacement, turbine, ultrasonic, and variable area/volume measurement. When there are particulates in the media, extreme temperatures, pressures, or low flow applications, certain factors must be considered when selecting the right flow meter for the application.

Quantity switch

A process tool that measures the flow rate of a medium at a set point as it passes through a pipe or other container. The medium being measured is usually gas, liquid or mud. There are many technologies used for flow switches, some of which include thermal, ultrasonic, and variable area/volume. When the media has particulate matter, extreme temperatures, pressures, or is in a low-flow application, certain factors must be considered when selecting the right flow switch for the application.

medium

Liquids are typically classified as liquids, gases, or vapors. Liquids are actually incompressible and occupy a certain volume. Gases and vapors are compressible, filling any volume at a known or given pressure.

Hole meter

Any flow meter that typically uses an entire flow team for flow measurement. Full-bore instruments may include threaded or flanged process connections and typically have the same process connection size as a given pipe size.

Every flow meter applies energy to the system in the form of pressure or head. In addition to the instrument, all accessories, valves and even straight pipes will affect the head flow meter to a certain extent. The fewer heads the flow meter introduces into the system, the better. The energy lost due to friction causes resistance to flow, called head

Inflow meter

Any flow meter that is inserted into a piping system, usually through a pipe insertion port or an isolation valve manufactured into the process piping system. Insertion flow meters are generally classified as any device that infers overall flow rate based on a single measurement of fluid velocity at strategic locations within a pipe. A typical insertion instrument consists of a sensing element, support structure attachment mounting, and a pressure seal. Used only in measurements, the accuracy of the instrument is based on the assumption that there is a known relationship between the measured velocity and the average fluid or gas velocity.

Factor

K-Factor - The K-factor of a flow meter is the ratio of the meter output in a pulse to the corresponding total amount of fluid passing through the meter during the measurement. The change in K-factor can be presented as a function of Reynolds number or flow rate. Flow meter manufacturers can generate K-factor versus Reynolds number curves when the meter is calibrated on a convenient fluid (usually water or air). The K-factor may vary due to thermal effects on the instrument body or between pipe schedules.

Flow

Laminar flow - A flow condition when a fluid flows in parallel layers, with no interruption between layers. Laminar flow is the ideal flow condition for gas flow when all air molecules move forward together along the pipe. High-efficiency airflow systems should have a Reynolds number of less than 2300.

Don't switch

A process instrument that measures the level of media points in barrels, vessels, flues, tanks, weirs or other vessels. The medium being measured is usually a liquid, slurry or solid. Three common technologies for level switches include guided wave radar, non-contact ultrasonic, and vibration. When the medium has a low dielectric constant, is extremely hot, or is in a foam or vapor zone, appropriate level switching technology must be selected for accurate measurement and durability.

No transmitter

A process instrument that measures the level of a continuous medium in a barrel, vessel, flue, tank, weir, or other container. The medium being measured is usually a liquid, slurry or solid. Two common technologies for horizontal transmitters include non-contact ultrasonic and guided wave radar. When the medium has a low dielectric constant, is extremely hot, or is in a foam or vapor zone, appropriate horizontal emitter technology must be selected for accurate measurement and durability.

Flow meter

A flow meter that uses the Coriolis principle to measure the mass of the medium passing through the meter in one unit of time. Mass flow meters generally have a higher cost than other instrumentation technologies and are very accurate. Typical applications for mass flow meters include gases, industrial coatings, methanol/catalyst streams, and oils.

Open channel flow meter

A flow meter that measures the level of flow through a channel of known size. By using a flue or flue, the flow level can be plugged into a mathematical formula to determine the flow rate. Given the way open channel flow meter measure flow rate, the meter itself consists of a level transmitter as well as a process monitor that is capable of converting from level to flow rate, depending on other factors involved. Typical applications for open channel flow meters include wastewater flows, gravity-fed sewer lines, stormwater monitoring, and clarifier flows. Waste and wastewater are the main industries for this type of flow meter.

Displacement flow meter

A flow meter that measures the displacement of a gear or spur as media passes through the meter. This type of measurement uses the volumetric principle of measurement by counting gears or spurs as they move a known volume of media. These gauges maintain consistent accuracy despite changing viscosity conditions and are frequently installed in brake fluid, fuel, glue, grease, oil, polymer and Skydrol applications.

Process display

Process tools to monitor and display process conditions. A process display may display its measurements via digital readout, scale, or other means. A process display with data input, usually including a method for outputting data, such as an analog loop output. Process displays come in a variety of configurations, and it is important to choose a display that has all the features required by your application.
[

Chemical flow meter

A flow meter that measures flow to determine flow rate. Volumetric flow meters are also commonly known as variable area flow meters, cycle meters, and rotation meters. A purge flow meter is a flow meter that meets the classic definition of a rotary meter and is designed for low flow rates. The flow passes through a meter lift ball or other indicator that can be read directly from the scale within the meter. If the media contains particulate matter, filtration is required. Typical purge flow meter applications include measuring low-flow liquids and gases, including oxygen, nitrogen, air, helium, water, and deionized water.

Notts number

Dimensionless quantities for predicting flow patterns in liquid and gas flow systems. Reynolds number is used to predict the transition from Laminar flow to turbulent conditions.
Turbulent and laminar flows can also be calculated, use the following formula to determine what is called
Reynolds number: re = vd/μ
Where:

AgainIt's Reynolds number.
\Is the air density.
vIs the average speed.
dIs the diameter of the pipe.
μIs the dynamic viscosity.

Tammy/Spinometer

See Volumetric Flow Meter.

Mass Flow Meter

Flow meters measure continuous flow by detecting thermal changes in the medium as it flows through the sensor. For reference, thermal mass flow meters are commonly used in air conditioning, dust collection, energy conservation systems, potable/non-potable water, sulfuric acid, and ventilation monitoring.

Mass flow switch

A flow switch that measures flow by detecting thermal changes in the medium as it flows through the sensor. Thermal mass flow switches are used in chemical feed systems, chiller water feeds, combustion cooling systems, damping regulators, for pump protection and ventilation.

Flow

A condition in which fluid flow fluctuates irregularly in a channel or layer. The velocity or velocity of a flow that moves with irregular amplitude and direction. Turbulent flow is the most efficient flow condition because air molecules spend so much energy bouncing off the pipe walls, forward, backward, and sideways, that they spend so much energy moving away from the pipe.

Rotation meter

A flow meter that measures vane displacement as media passes through the meter. This type of measurement is based on velocity. In contrast to positive displacement flow meters, which count gears or spurs to determine how much the medium moves, turbine flow meters measure flow rate based on how fast the medium moves through the meter. Turbine gauges are often used with abrasive and corrosive liquids because of their accuracy and mechanical integrity. Typical applications include chemical processing, coal bed methane applications, hydraulic applications, pesticide manufacturing, reclamation and secondary oil recovery.

Sonic flow meter

A flow meter calculates the flow rate of a medium as it sends ultrasonic waves between the instrument sensors. Ultrasonic flow meters will average the transit time of a beam, or use the Doppler effect to measure changes in frequency to determine flow rate. The ultrasonic flow meter is non-invasive, meaning it is installed outside the pipe. Since no access is required, installing the instrumentation does not require interruption of the process. Typical ultrasonic flow meter applications are aerated liquids, dredged soil, plastics, pulp, sludge, slurry and sewage.

Show with process

As standard factory configuration, process displays for various monitoring process applications are provided. Generic process displays typically include a communications interface (such as RS-485 and/or Ethernet) and outputs for controlling relays. "Universal" means the device has more functionality built into it than a standard process monitor.

Variable area flow meter

See Volumetric Flow Meter.

Degree flow meter

A flow meter that measures the speed or velocity of a given fluid or mass, usually based on the fluid's internal volume flow rate at which the fluid is opened.

Volume flow meter

A flow meter that measures flow to determine flow rate. Volumetric flow meters are also commonly known as variable area flow meters, cycle meters, and rotation meters. In the FLO-CORP line, we call our MEMFlo™ flow meter lines our volume lines. MEMFlo flow meters use the volumetric principle of measurement to determine flow rate and have greater functionality than classic volumetric/variable area flow meters.
Our MEMFlo™ flow meter lines are extremely rugged, available in all metals for high temperatures and pressures, and are capable of handling suspension in media
Solid. Classic volumetric/variable area flow meter cannot handle particulate matter and require filtration before the media enters the flow meter. Additionally, other instruments use the quantity measurement principle, including positive displacement flow meter and volume meters. Positive displacement flow meters count gears or spurs to determine the known volume of media passing through the meter: Even though these meters use design volume measurements, the name refers to the way the medium displaces the gears or spurs to determine flow rate. Water flow meters typically rely on positive displacement (volume) or turbine (velocity) measurements.

Online monitoring

Monitoring done without the use of wires between the device reporting data and the interface receiving it. For example, cellular wireless devices wirelessly report data to cell towers. Then, view the reported process data through the web interface. In this example, wires might be used to connect process measurement equipment to cellular transmitters in the field, and the wires are used to move the data once it reaches the cell tower. Regardless, the process involves wireless monitoring, as field devices can report data at some stage of the process without having to use a hard-wired connection.
Wireless monitoring can use a variety of transmission methods, including Bluetooth, wifi, cellular, and satellite
Wait. Consider another example of a horizontal launcher mounted on a tank truck. Level transmitters periodically measure the tanker truck's level when pickups and/or deliveries are made. At set intervals and/or trigger points, wireless monitoring devices report via cellular or satellite data. These data are then available through a web interface. As long as the tanker is in a battery coverage area or has unobstructed contact with the satellite, data is reported via wireless monitoring. Once the data is reported, it can be viewed by logging into the web interface or software interface. Additional functionality is also available through the interface, including wirelessly configuring reporting devices, setting up email/text alerts, GPS location (if the device is GPS capable), and other information.

Line monitoring system

A device (or devices) that processes data using wireless communications to report measurements from process instruments (flow meters, level transmitters, etc.). Provides processing data, configuration functions, and other functions as an interface to the system through software or a web interface. Wireless surveillance systems are a type of machine-to-machine (M2M) functionality. See Wireless Monitoring.