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Showing posts with the label Flow

Thermal mass flow meter working principle and Applications

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  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 flow se

Orifice flow meter

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  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 losses in th

Turbine flow meter

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  Turbine flow meter A turbine flow meter is used for volumetric total flow and/or flow rate measurement and has a relatively simple working principle. As fluid flows through the turbine meter, it impinges upon turbine blades that are free to rotate about an axis along the center line of the turbine housing.  Turbine flow meters use the mechanical energy of the liquid to rotate a rotor within the flow stream. The rotational speed is directly proportional to the velocity of the fluid traveling through the meter. These meters are used in multiple industries to reliably measure liquids, gases and vapors. Introduction Turbine flow meters are used to measure clean, dry gases and liquids such as hydrocarbons, chemicals, gases and vapors, fuels and other types of liquids with lower viscosity, and for applications requiring highly accurate and precise measurements. These turbine flow meters are mostly used for military applications. They are also used in blending systems in the petroleum indus

What is a Orifice Plate and explain

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  Orifice Plate   The orifice plate is the most common form of restriction that is used in flow measurement. An orifice plate is basically a thin metal plate with a hole bored in the center. It has a tab on one side where the specification of the plate is stamped. The upstream side of the orifice plate usually has a sharp, edge. below Figure shows a representative orifice plate. When an orifice plate is installed in a flow line (usually clamped between a pair of flanges), increase of fluid flow velocity through the reduced area at the orifice develops a differential pressure across the orifice. This pressure is a function of flow rate.  With an orifice plate in the pipe work, static pressure increases slightly upstream of the orifice (due to back pressure effect) and then decreases sharply as the flow passes through the orifice, reaching a minimum at a point called the vena contracta where the velocity of the flow is at a maximum. Beyond this point, static pressure starts to recover as

What is Flange Taps

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  Flange Taps   Flange taps are the most widely used pressure tapping location for orifices. They are holes bored through the flanges, located one inch upstream and one inch downstream from the respective faces of the orifice plate. A typical flange tap installation is shown in below Figure. The upstream and downstream sides of the orifice plate are connected to the high pressure and low-pressure sides of a DP transmitter. A pressure transmitter, when installed to measure flow, can be called a flow transmitter. As in the case of level measurement, the static pressure in the pipe-work could be many times higher than the differential pressure created by the orifice plate. In order to use a capsule that is sensitive to low differential pressure, a three valve manifoldhas to be used to protect the DP capsule from being over ranged. The three valve manifold is discussed in more detail in the  level measurement.

What is a Orifice Plate

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  Orifice Plate   The orifice plate is the most common form of restriction that is used in flow measurement. An orifice plate is basically a thin metal plate with a hole bored in the center. It has a tab on one side where the specification of the plate is stamped. The upstream side of the orifice plate usually has a sharp, edge. below Figure shows a representative orifice plate. When an orifice plate is installed in a flow line (usually clamped between a pair of flanges), increase of fluid flow velocity through the reduced area at the orifice develops a differential pressure across the orifice. This pressure is a function of flow rate.  With an orifice plate in the pipe work, static pressure increases slightly upstream of the orifice (due to back pressure effect) and then decreases sharply as the flow passes through the orifice, reaching a minimum at a point called the vena contracta where the velocity of the flow is at a maximum. Beyond this point, static pressure starts to recover as

What is a Flow Detectors

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  Flow Detectors  To measure the rate of flow by the differential pressure method, some form of restriction is placed in the pipeline to create a pressure drop. Since flow in the pipe must pass through a reduced area, the pressure before the restriction is higher than after or downstream. Such a reduction in pressure will cause an increase in the fluid velocity because the same amount of flow must take place before the restriction as after it. Velocity will vary directly with the flow and as the flow increases a greater pressure differential will occur across the restriction. So by measuring the differential pressure across a restriction, one can measure the rate of flow.

Working Principle of Vortex Flow Meter

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  Working Principle of Vortex Flow Meter Vortex flow meters utilize a bluff body or cylinder mounted in a pipe spool that creates alternating vortices behind the cylinder. The frequency of the alternating vortex is proportional to the fluid velocity. Vortex flow meters have no moving parts to maintain or repair, and the signal is read electronically and simply converted to a flow rate. Vortex meters work well with most clean fluids and have similar application ranges to DP  flow  meters. Vortex flow meters are also referred to as vortex shedding flow meters or oscillatory flow meters. These types of flow meters are used to measure the vibrations of the downstream vortexes caused by an obstruction in the flowing stream. Each obstruction has a vital liquid flow speed at which vortex shedding takes place. This vortex shedding occurs at the instant when alternating low pressure zones gets created in the downstream. These sporadic pressure zones enable the barrier to move towards the low pr

Coriolis flow meters working principle advantages, disadvantages and application

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  Coriolis flow meters Coriolis flow meter operate on the principal that, if a particle inside a rotating body moves in a direction toward or away from the center of rotation, the particle generates inertial forces that act on the body.  The operation of a Coriolis flow meter is based on the mechanics of motion. The Coriolis force happens when a mass moves in a rotating inertial frame. The rotation is created by vibrating two opposing tubes on the flow meter. When a fluid flows through the opposed vibrating tubes, the tubes twist due to the Coriolis force. The twisting alternates with the vibration and creates two phase-shifted sinusoidal wave forms on coils mounted to the tubes. The amount of shift is proportional to the mass flow rate. In addition, the frequency of vibration is proportional to the fluid density. Coriolis Flow Meter Principles The basic operation of Coriolis flow meters is based on the principles of motion mechanics. As fluid moves through a vibrating tube it is force

Flow Measurements Questions and answer

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  Q & A For Flow Measurements 1.Convert the flow of 3 Cu ft/min into Cu meters/hour. Solution 1 Cu ft/min = 1.699 Cu meters/hour So, 3 Cu ft/min = 3 x 1.699 Cu meters/hour  = 5.097 Cu meters/hour  2 .Convert the flow of 9 Imp. Gallons into Barrels(oil). Solution 1 Imp. Gallons = 0.0286 Barrels So, 9 Imp. Gallons = 9 x 0.0286 Barrels  = 0.2574 Barrels 3.Convert the flow of 2 lb./sec into gm/min. Solution 1lb./sec = 27220 gm/min So, 2 lb./sec = 2 x 27220 gm/min  = 54440 gm/min 4. Convert the flow of 10 meter/sec into cm/sec.  Solution 1 meter/sec = 100 cm/sec So, 10 meter/sec = 10 x 100 cm/sec  = 1000 cm/sec   5. Convert the flow of 18 ft/sec into meter/min . Solution 1 ft/sec = 18.29 meter/min So, 18 ft/sec = 18 x 18.29 meter/min  = 329.22 meter/min 6. Convert the flow of 57 ft/min into meter/sec. Solution  1 ft/min = 0.005080 meter/sec  So, 57 ft/sec =57 x 0.005080 meter/sec  =0.28956 meter/sec 7. Convert the flow of 10 Imp. Gallons into Barrels. Solution  1 Imp. Gallon = 0.0286 Ba

Vortex Flow Meter working principle and applications

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  Vortex Flow Meter Vortex flow meters utilize a bluff body or cylinder mounted in a pipe spool that creates alternating vortices behind the cylinder. The frequency of the alternating vortex is proportional to the fluid velocity. Vortex flow meters have no moving parts to maintain or repair, and the signal is read electronically and simply converted to a flow rate. Vortex meters work well with most clean fluids and have similar application ranges to DP flow meters. Working Principle of Vortex Flow Meter Vortex flow meters utilize a bluff body or cylinder mounted in a pipe spool that creates alternating vortices behind the cylinder. The frequency of the alternating vortex is proportional to the fluid velocity. Vortex flow meters have no moving parts to maintain or repair, and the signal is read electronically and simply converted to a flow rate. Vortex meters work well with most clean fluids and have similar application ranges to DP flow meters. Vortex flow meters are also referred to