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**Industrial Instrumentation**

Dr. –Ing. Naveed Ramzan PEC – UET Lahore Dr. Shahid Naveed März 2017 / Dr. –Ing Naveed Ramzan aaaa

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Flow Sensors If a flow meter is installed there will be costs involving the instrument, pipe work modification, secondary instrumentation, supplies, intrinsic safety, maintenance, calliberation checks etc. ………… PEC – UET Lahore Dr. Shahid Naveed März 2017 / Dr. –Ing Naveed Ramzan

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**Plant control, for product quality and safety reasons. **

Reasons for Flow Metering Plant control, for product quality and safety reasons. Custody transfer, both interplant and selling to outside customers. Filling of containers, stock tanks and transporters. Energy, mass balancing for costing purpose and health monitoring of heat exchangers. Health monitoring of pipelines and on-line analysis equipment, Government and company legislation may dictate the use here of such equipment. PEC – UET Lahore Dr. Shahid Naveed März 2017 / Dr. –Ing Naveed Ramzan

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**Differential Pressure Meters. Rotary Meters.**

Types of Flow Meters Differential Pressure Meters. Rotary Meters. Displacement Inferential New Flow Meters. Electromagnetic Vortex Shedding Ultrasonic Cross Correlation Tracer Swirl Fluidic Point Velocity Meters. Mass Flow Maters. PEC – UET Lahore Dr. Shahid Naveed März 2017 / Dr. –Ing Naveed Ramzan

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**Orifice Plate Dall Tube Venturi Tube Pitot Tube Rota meter**

Differential Pressure Meters Orifice Plate Dall Tube Venturi Tube Pitot Tube Rota meter Target mater Averaging Pitot Nozzle Spring Loaded Intake Meter Elbow Meter Bypass Meter PEC – UET Lahore Dr. Shahid Naveed März 2017 / Dr. –Ing Naveed Ramzan

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**Parts of differential flow meters**

Primary element (Part of meter used to restrict the fluid flow in pipe line to produce differential pressure) They include Orifice plate Venturi tubes Flow nozzles Pitot tube etc.

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**Force balance meters etc.**

Parts of differential flow meters Secondary element (measure the differential pressure produced by primary elements and convert them to usable forces or signals ) Secondary elements; Manometers Bellow meters Force balance meters etc.

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Obstruction Meters Orifice Meters Venturi Meters Flow Nozzles

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**Flow Through an Orifice Meter**

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**Flow Through an Orifice Meter**

P1 P2 d D P1 P

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**Flow Through an Orifice Meter**

Cheapest and Simplest But biggest pressure drop and power lost (C~ ) Side Note: Pressure drop caused by friction and turbulence of shear layer downstream of vena contracta 10k Re 0.85 5000 100k 0.6 b=d/D 0.1 0.8

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Obstruction Meters Orifice Meters Venturi Meters Flow Nozzles

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**Flow through a Venturi Meter**

In a venturi, 0.95 < C < 0.98 Advantage: Pressure recovery Uses little power

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Back to the Nozzle P1 P2 P1 P P2

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**Shorter and cheaper than venturi But larger pressure drop. **

The Nozzle Flowmeter Shorter and cheaper than venturi But larger pressure drop. Thus, more power lost in operating. 0.98 C 0.86 105 103 Re

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Obstruction Meters Orifice Meters Venturi Meters Flow Nozzles

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**Total pressure is constant throughout**

Flow through a Nozzle Basic Equations: a.) Continuity: mass in = mass out b.) Bernoulli’s Eqn. Total pressure is constant throughout

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Flow through a Nozzle

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Flow through a Nozzle

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Flow through a Nozzle DP

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**Flow through a Nozzle Y = Compressibility Factor**

=1 for incompressible flow or when DP<< Pabs C= Discharge Coefficient =f(Re) and nature of specific flow meter DP P

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**Elbow Flow meter Rota meter Force balance Drag Force Gravity Buoyancy**

Differential Pressure Meters ( Cont‘d) Force balance Drag Force Gravity Buoyancy (usually negligible) Elbow Flow meter Rota meter PEC – UET Lahore Dr. Shahid Naveed März 2017 / Dr. –Ing Naveed Ramzan aaaa

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**Rotameter, variable-area-flowmeter**

Force balance Drag Force Gravity Buoyancy (usually negligible) Derived on next slide

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**For a fixed x-position, A is fixed. Then**

Rotameter Equations For a fixed x-position, A is fixed. Then

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Pitot Tube

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**Displacement Meters Gear Oval wheel Vane Meter Gear (Roots)**

Rotary Meters ( Displacement Meters) Displacement Meters Gear Oval wheel Vane Meter Gear (Roots) Diaphragm Meter Liquid Sealed Meter Inferential Meters Turbine Meter Hoverflo Meter -- This family of meters separates the incoming liquid or gas into discrete volumes and is transfering them downstream operates a counting mechanism. They are mainly used where a high order of accuracy is required and stoppage of the flow in an event is not an embarrasment. --- extensively used for custody transfer of oils and fuels PEC – UET Lahore Dr. Shahid Naveed März 2017 / Dr. –Ing Naveed Ramzan aaaa

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**What are Rotary Meters ( Displacement Meters)**

Devices which are used to measure mass or volumetric flow rate of gas or liquid by using a rotating element. 25/03/2017

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**Positive Displacement Rotary Meters Inferential Rotary Meters**

Types of Rotary Meters ( Displacement Meters) Types of Rotary Meters Positive Displacement Rotary Meters Inferential Rotary Meters 25/03/2017

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**PD Rotary Meters ( Displacement Meters)**

Positive displacement flow meters, also know as PD meters, measure volumes of fluid flowing through by counting repeatedly the filling and discharging of known fixed volumes. 25/03/2017

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**Principle of Operation**

PD Rotary Meters ( Displacement Meters) Principle of Operation POSITION 1. As the bottom impeller rotates in a counterclockwise direction towards a horizontal position, fluid enters the space between the impeller and cylinder. POSITION 2. At the horizontal position, a definite volume of fluid is contained in the bottom compartment. 25/03/2017

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**Principle of Operation**

PD Rotary Meters ( Displacement Meters) Principle of Operation POSITION 3. As the impeller continues to turn, the volume of fluid is discharged out the other side. POSITION 4. The top impeller, rotating in opposite direction, has closed to its horizontal position confining another known and equal volume of fluid. 25/03/2017

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**Oval Gear Nutating Disk Oscillating Piston Multi Piston**

PD Rotary Meters ( Displacement Meters) Oval Gear Nutating Disk Oscillating Piston Multi Piston Rotating Impellers Rotating Valve Birotor Roots Meter Helix Meters 25/03/2017

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**PD Rotary Meters ( Displacement Meters)**

Nutating Disk A nutating disc meter has a round disc mounted on a spindle in a cylindrical chamber. By tracking the movements of the spindle, the flowmeter determines the number of times the chamber traps and empties fluid. 25/03/2017

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**PD Rotary Meters ( Displacement Meters)**

Oval Gear Two identical oval rotors mesh together by means of slots around the gear perimeter. The oval shaped gears are used to sweep out an exact volume of the liquid passing through the measurement chamber during each rotation. 25/03/2017

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**The flow rate can be calculated by measuring the rotation speed.**

PD Rotary Meters ( Displacement Meters) Oval Gear The flow rate can be calculated by measuring the rotation speed. 25/03/2017

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**The roots meter is similar in many respects to the oval gear meter.**

PD Rotary Meters ( Displacement Meters) Roots Meter The roots meter is similar in many respects to the oval gear meter. Two-lobed impellers rotate in opposite directions to each other within the body housing. 25/03/2017

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**The flow rate can be calculated by measuring the rotation speed.**

PD Rotary Meters ( Displacement Meters) Roots Meter These peanut-shaped gears sweep out an exact volume of liquid passing through the measurement chamber during each rotation. The flow rate can be calculated by measuring the rotation speed. 25/03/2017

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**PD Rotary Meters ( Displacement Meters)**

Rotating Impeller Birotor 25/03/2017

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**Functions without external power**

PD Rotary Meters ( Displacement Meters) Advantages High accuracy over a wide range of viscosities and flow rates up to 2000 cP with proper clearances. Extremely good repeatability on high viscosity fluids, very low slippage, long life if little or no abrasive material in the fluid Low pressure drop Functions without external power 25/03/2017

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**Rotary Meters ( Displacement Meters)**

-- This family of meters separates the incoming liquid or gas into discrete volumes and is transfering them downstream operates a counting mechanism. They are mainly used where a high order of accuracy is required and stoppage of the flow in an event is not an embarrasment. --- extensively used for custody transfer of oils and fuels PEC – UET Lahore Dr. Shahid Naveed März 2017 / Dr. –Ing Naveed Ramzan aaaa

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**Special construction available for high viscosities and temperatures **

PD Rotary Meters ( Displacement Meters) Advantages Special construction available for high viscosities and temperatures Can register near zero flow rate Measures directly, not an inferential device, for more consistent results Easy to repair and economical. 25/03/2017

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**Increased maintenance compared to other meters, more moving parts **

PD Rotary Meters ( Displacement Meters) Disadvantages Increased maintenance compared to other meters, more moving parts May become damaged by flow surges and gas slugs Chance of corrosion and erosion from abrasive materials Derated flow rate capacity for high viscosities and temperatures Relatively high cost for large sizes 25/03/2017

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Inferential Meters The inferential type meters are so-called because rather than measuring the actual volume of fluid passing through them, they “infer” the volume by measuring some other aspect of the fluid flow and calculating the volume based on the measurements 25/03/2017

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Inferential Meters The inferential type meters are so-called because rather than measuring the actual volume of fluid passing through them, they “infer” the volume by measuring some other aspect of the fluid flow and calculating the volume based on the measurements Turbine Meters Paddle Wheel Insertion Type 25/03/2017

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Turbine Flow Meters A turbine with blades filling the meter can rotate freely on bearings. As the fluid passes it spins the blades round and a magnetic sensor in the body transmits pulses to pulse counting circuits. It is easily dismantled and if calibrated is very accurate PEC – UET Lahore Dr. Shahid Naveed März 2017 / Dr. –Ing Naveed Ramzan

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Turbine Flow Meters It consists of a multi-bladed rotor mounted at right angles to the flow and suspended in the fluid stream on a free-running bearing. The diameter of the rotor is very slightly less than the inside diameter of the metering chamber, and its speed of rotation is proportional to the volumetric flow rate. 25/03/2017

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Turbine Flow Meters The rotational speed is a direct function of flow rate and can be sensed by magnetic pick-up, photoelectric cell, or gears. Electrical pulses can be counted and totalized. 25/03/2017

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Paddle Wheel Meters Paddle Wheel 25/03/2017

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**Very good repeatability Reduced susceptibility to fouling and deposits **

Inferential Meters Advantages Very good repeatability Reduced susceptibility to fouling and deposits Less sensitive to viscosity changes Available in large sizes, good value for high flow rates Low maintenance Registers near zero flow rate Disadvantages High pressure drop that increases drastically with viscosity Relatively high cost Indirect measurement 25/03/2017

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**Ultrasonic Flow Meters**

New Flow Meters Electromagnetic EM Meter Vortex Shedding Meter Vortex Generation Meter Ultrasonic Flow Meters PEC – UET Lahore Dr. Shahid Naveed März 2017 / Dr. –Ing Naveed Ramzan

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**New Flow Meters (Cont‘d)**

Magnetic Flowmeter Based upon Faraday’s Law The fluid is the conductor, must be electrically conductive. E=BDVx10-8 E=voltage, volts B=magnetic flux density, gauss D= length of the conductor, cm V=velocity of the conductor, cm/sec PEC – UET Lahore Dr. Shahid Naveed März 2017 / Dr. –Ing Naveed Ramzan

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**New Flow Meters (Cont‘d)**

Swirl Meter PEC – UET Lahore Dr. Shahid Naveed März 2017 / Dr. –Ing Naveed Ramzan

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**Coriolis Mass Flowmeter**

In the Coriolis meter the fluid is passed through a tube. The tubes are available in different design like tubes of U-shape or horseshoe-shaped. The tubes can either be curved or straight. When two tubes are used the flow is divided when entering the meter and then recombined. The flow when enters the tube encounters oscillating excitation force that causes the tubes to vibrate at a fixed frequency. The vibration is induced in the direction that is perpendicular to flow of fluid. This creates the rotation frame of reference. Consider the tube during oscillation moving up and downward, when the tube is moving upward the fluid flowing in it tends to resist this and forces it downward. When the tube moves in the opposite direction, so does the fluid and a twist in introduced in the tube. All this might not be visible by directly observing. The twist at inlet of fluid and outlet of fluid results in phase difference or time lag and that is dependent on the fluid mass passing through the tube. PEC – UET Lahore Dr. Shahid Naveed März 2017 / Dr. –Ing Naveed Ramzan

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**Discussion & Questions?**

Dr. Shahid Naveed März 2017 / Dr. –Ing Naveed Ramzan

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