Annubar flow meter An annubar is very similar to a pitot tube. The difference is that there is more than one hole into the pressure measuring chambers. The pressure in the high-pressure chamber represents an average of the velocity across the pipe. Annubars are more accurate than pitots as they are not as position sensitive or as sensitive to the velocity profile of the fluid. There may be a single port or multiple tapping ports on the opposite side of the bar to measure the low static pressure in the downstream region. The difference between the total and static pressures is effectively a measure of the fluid velocity head, which together with the pipe area enables the volumetric flowrate to be determined. Annubar flow meter Principle The  Annubar primary flow element is a device used to measure the flow of a liquid, gas or steam fluid that flows through a pipe. It enables flow measurement by creating a differential pressure (DP) that is proportional to the square of the ve...

Ultrasonic Flow Meter Working Animation

  Flow Meter Questions and Answers 1. What are the major three methods of flow meters? Area flow meter Mass flow meter Quantity meters 2. List some examples of the inferential flow meter. In the inferential type of flow metering techniques, the out quantity flow rate is inferred from a characteristic effect of a related phenomenon. Turbine flow meters Target flow meters Ultrasonic flow meters 3. What are the different types of positive displacement meters? Reciprocating piston type Rotating vane type Nutating disk type Lobed impellar type Oscillating piston type 4. What are the different types of thermal flow meters? Heat transfer flow meters Hot wire flow meters 5. Name the different types of weighing methods  Semiconductor feed belt weighing ( Batch weighing) Continuous conveyor scale radio active transmission gauge volumetric solid methods 6. Write any two points of calibration of flow meter Wet meter – manometer which is calibrated with mercury Dry meter – manometer whic...

  Flow Nozzle What is Flow Nozzle ? Flow Nozzle has a smooth elliptical inlet leading to a throat section with a sharp outlet. Restriction in the fluid flow causes a pressure drop, which relates to the flow rate by applying Bernoulli’s equation. The smooth inlet of the Flow Nozzle results in a higher coefficient of discharge than most other differential meters. This higher efficiency means greater flow capacity when compared to most other differential meters of the same size. How it works Flow nozzles are often used as measuring elements for air and gas flow in industrial applications. When a gas/liquid accelerate through a nozzle, the velocity increase and the pressure and density decrease. The maximum velocity is achieved at the throat. After the pressure difference has been generated in the differential pressure flow meter. Flow rate can be calculated. Flow Nozzle Principle When a flow nozzle is placed in a pipe carrying whose rate of flow is to be measured, the flow nozzle caus...

Positive displacement flow meter Introduction A positive displacement meter is a type of flow meter that requires fluid to mechanically displace components in the meter in order for flow measurement. Positive displacement flow meters measure the volumetric flow rate of a moving fluid or gas by dividing the media into fixed, metered volumes.  Positive displacement flow meters are very accurate and have high turndown. They can be used in very viscous, dirty and corrosive fluids and essentially require no straight runs of pipe for fluid flow stream conditioning though pressure drop can be an issue. They are widely used in the custody transfer of oils and liquid fluids (gasoline) and are applied on residential home natural gas and water metering. A diaphragm meter, with which most homes are equipped, is an example of a positive displacement meter. This type of meter is appealing in certain custody transfer flow applications where it is critical that the metering be functional in order ...

 Magnetic flow meter ( Electromagnetic flow meter) A magnetic flow meter (electromagnetic flow meter) is a transducer that measures fluid flow by the voltage induced across the liquid by its flow through a magnetic field. A magnetic field is applied to the metering tube, which results in a potential difference proportional to the flow velocity perpendicular to the flux lines. The physical principle at work is electromagnetic induction. The magnetic flow meter requires a conducting fluid, for example, water that contains ions, and an electrical insulating pipe surface, for example, a rubber-lined steel tube. Electromagnetic Flow Meters Working Principle Electromagnetic Flow Meters, simply known as mag flow meter is a volumetric flow meter which is ideally used for waste water applications and other applications that experience low pressure drop and with appropriate liquid conductivity required. The device doesn’t have any moving parts and cannot work with hydrocarbons and distilled ...

  Ultrasonic flow meter An ultrasonic flow meter can be defined as, a meter that is used to measure liquid velocity with ultrasound to analyze the volume of liquid flow.  Ultrasonic Flow Meters Working Principle Ultrasonic flow meters calculate the flow rate by utilizing the speed of sound through a fluid created by transducers mounted to the pipe wall. There are two types of ultrasonic meters: Doppler and Time-of-Flight. The Doppler ultrasonic meter requires particles in the fluid to reflect sound waves back to the pipe wall transducers. The difference in frequency between the sent and reflected wave is proportional to fluid velocity. The Time-of-Flight ultrasonic meter requires a clean fluid and works by using opposing transducers mounted to transmit/receive sound waves at an angle across the pipe. The difference in the time required to send a pulse along the path between transducers in the direction of flow vs. against the flow is proportional to...

  Thermal mass flow meter Thermal mass flow meters are designed to accurately monitor and measure mass flow (as opposed to measuring volumetric flow) of clean gases, a parameter that is not temperature dependent. Therefore, the thermal mass flow meter does not require a correction for changes in gas temperature, pressure, viscosity and density. Thermal Mass Flow meter Working Principle The thermal mass meter measures gas flow based on the concept of convective heat transfer. The flow meters are available in either inline flow bodies or insertion-style. In either case, the meter’s probe inserts into a gas stream of a pipe, stack or duct. Toward the tip of the meter’s probe are two sensors. These sensors are resistance temperature detectors (RTDs) or resistance thermometers and measure temperature. The RTDs consist of durable reference-grade platinum windings clad in a protective 316 SS or Hastelloy C sheath. One of the RTDs is heated by an integrated circuit and functions as the flo...

  Orifice  flow meter An orifice in a pipeline is shown in below figure with a manometer for measuring the drop in pressure (differential) as the fluid passes thru the orifice. The minimum cross sectional area of the jet is known as the “vena contracta.” How does it work? As the fluid approaches the orifice the pressure increases slightly and then drops suddenly as the orifice is passed. It continues to drop until the “vena-contracta” is reached and then gradually increases until at approximately 5 to 8 diameters downstream a maximum pressure point is reached that will be lower than the pressure upstream of the orifice. The decrease in pressure as the fluid passes thru the orifice is a result of the increased velocity of the gas passing thru the reduced area of the orifice. When the velocity decreases as the fluid leaves the orifice the pressure increases and tends to return to its original level. All of the pressure loss is not recovered because of friction and turbulence los...