Instrumentation Basics.


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Weight is a working parameter that is significant in numerous applications. ... Weight connected over a given region can be utilized for valuable work. ...
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Instrumentation Fundamentals Module 1 – Pressure Scales Units of Pressure Scales & Conversions Atmospheric, PSIG, PSIA, PSID, Bar Manometers

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Pressure This module will cover: The material science of weight Units of measure (SI, Metric, Imperial) Pressure scales and transformations How weight is measured Elastic components (bourdon, cries stomach) Electrical components (strain gage, piezoelectric) Sensors, Switches and Transmitters

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What is it? Weight is a working parameter that is important in numerous applications. (like voltage in an electric circuit) Pressure connected over a given range can be utilized for helpful work. Steam weight, Water weight Pressures can be measured to deduce the state of different procedure parameters. Stream, level

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Force Area Pressure = The Physics of Pressure is characterized as "power per unit range" Therefore any article or material having a weight will apply a weight over the region the power is following up on.

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Force Area Pressure = The Units of Pressure is characterized as "power per unit region" Pound power, Kilogram power Newton, dyne Square Inches, Square feet Square Centimeters, Square Meters Common units include: Pounds per Square Inch (psi) KiloPascals (kPa)

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550 lbs 708 lbs 62.4 lbs 849 lbs Example of weight from a 1 cubic foot pound power following up on a surface Each base has a zone of 144 in 2 1 cubic foot of copper 550 lbs 144 in2 = 3.8 psi 1 cubic foot of lead 708 lbs 144 in2 = 4.9 psi 1 cubic foot of water 62.4 lbs 144 in2 = 0.43 psi 1 cubic foot of mercury 849 lbs 144 in2 = 5.9 psi

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More Pressure Scales PSI and kPa are the most widely recognized weight scales yet there a couple of additional: Inches* of water Inches* of mercury Bar Atmos Torr (vacuum) * or millimeters when utilizing metric

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Example of the different weight scales The same procedure weight is being connected to every gage. Every gage has an alternate scale alignment. 27.6806 "H20 2.03602 "Hg 0.068947 Bar 0.068046 Atmos Applied procedure weight is 1 psi or 6.89 kPa The decision of scales will rely on upon the measure of weight being measured (high weight = psi/kPa, low weight = inches H20) The kind of use ( stream = inches H20, circulatory strain = inches of Hg.)

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Conversion Factors Need to Know: psi and kPa change Imperial versus Metric versus SI 1 cubic foot of water that weighs 62.4 lbs acting over a range of 144 in 2 creates a weight of 0.433 pound for each square creep (psi) The same volume of water weighs 28.3 Kilograms over a region of 929 cm 2 , thusly the weight is 0.03 kilograms for every square centimeter. (30.46 g/cm 2 ) SI use Newton per sq. meter and call it the Pascal 1 psi = 0.006894757 Pascals = 6.895 k ilo Pa scals

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Need to Know Ball Parking: 1 psi ≈ 7 kPa 3 psi ≈ 21 kPa 15 psi ≈ 105 kPa 20 psi ≈ 140 kPa 3 to 15 psi is a typical weight territory 20 kPa to 100 kPa is additionally a typical weight territory

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12 inches of water applies a weight of 0.433 psi Inches of Water Scale This scale is utilized to gauge little weights. The properties of water are known and steady and can be utilized as an essential standard . Weight is extent to the stature of the water segment (hydrostatic head weight)

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Water Column The hydrostatic head created by a section of fluid is relative to the tallness and thickness of the fluid. P = tallness x (Density = Mass/Volume) Density of water is 0.0361 lbs/in 3 P = 12 x 0.0361 = 0.433 lbs/in 2 12 " H20 0.433 psi

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Water Column The more prominent the stature the more noteworthy the hydrostatic head. P = tallness x (Density = Mass/Volume) 24 " H20 Density of water is 0.0361 lbs/in 3 P = 24 x 0.0361 = 0.866 lbs/in 2 0.866 psi

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Applied Process Pressure Atmospheric Press Atmospheric Pressure h Height (h) of uprooted water = connected weight U-Tube Manometer Manometers can be utilized as an essential standard to quantify little weights

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Applied Process Pressure Atmospheric Press h Height (h) of dislodged water = connected weight Reading weight with a U-tube Manometer If the aggregate removal h = 3" the connected weight would be 3"H20 = 3"WC = 0.108 psi Using Mercury as a filling fluid builds the weight territory by 13.6 times.

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Well Type Manometers The well sort utilizes one measuring arm. Gives a bigger weight territory Mercury filled well sort manometers can make the grade regarding 30 psi and the sky is the limit from there. (6 footer) Can be utilized as an essential standard.

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Inclined Plane Manometer Used for little weight estimations. Extremely delicate, frequently used to quantify room weights.

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psi in environment Gage Pressure (psig) The standard weight estimation is referenced to air weight and is called gage weight . The scale units on the manometer could be adjusted in inches of water (gage) inches of mercury (gage) psig And all estimations would be in respect to air weight 14.7 psi (changes marginally with height and climate)

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Gage, Absolute and Atmospheric Pressure Any weight above environment is called gage weight (psig) Any weight beneath air is a vacuum (negative gage weight) Absolute weight (psia) is measured from an impeccable vacuum Differential Pressure (psid) has no reference to either supreme vacuum or barometrical weight

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Gage Pressure (psig) Applying 1 psi would create a removal of around 2 in. Hg or 30 in. H 2 O Since the reference side of the manometer is interested in environment, the connected weight would be perused as gage weight i.e. 1psig or only 1 psi 1 psi Atmos h

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Standard Gage When a gage has no info connected, it will read 0 psig The weight territory for this gage is 0 – 100 psi What is the reach in kPa? A few gages may exclude the "g" after psi, some will.

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Pressure Range & Scale This gage has a weight scope of 0 to 30 in. H 2 O The weight being measured is still gage weight . What is the most extreme psig that can be connected? kPa?

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Small weight estimations Dwyer differential weight gage enrolls a differential of 0 - 2 psi, 1/8" npt. High and low weight input ports on side and back. Manual set point. Max 15 psi and 140ºF. 4-3/4" width x 2" high.

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Examples of psig, psia and vacuum 20 psig = 20 + 14.7 = 34.7 psia 60 psia = 60 – 14.7 = 45.3 psig 10 psia = 10 – 14.7 = - 4.7 psig = - 4.7 = - 9.6 "Hg 0.0361 x13.6

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PSIA – Absolute Pressure A gage with a psia scale will show 14.7 when no weight is connected. The compound gage is more normal than psia, it gauges vacuum and gage weight. This gage has a scope of 0 – 30 in. Hg vacuum and 0 to 15 psig

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6 psi 2 psi 4 0.0361 x 13.6 h = 8.15 inches of H20 Differential Pressure (psid) Differential weight = 4 psid

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Differential Pressure Gage (psid) Requires 2 inputs. Must watch weight extremity, i.e. greetings side/lo side

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Differential Pressure Cell Transmitter The d/p cell is frequently used to gauge level and stream. What is the most extreme suitable info weight in psi? 4 – 20 mA yield 2 wire transmitter Differential Input 0 – 200 in. H20 Typical info range

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Pressure Conversion Chart Ball Parking 1 psi = 7 kPa 1 inch Hg = 0.5 psi 100 inch H20 = 3.5 psi 1 Bar = 1 Atmos = 14.7 psi Accurate 1 psi = 6.89 kPa 1 inch Hg = 0.49 psi 100 inch H20 = 3.61 psi 1 Bar = 14.5 psi = 100 kPa

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Exercise (ball park is fine) What is this in psi, kpa, inches of H20? What is this in psig, psia, inches of Hg?

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