Bourdon Gage Slides

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LAB # 2Calibration of

Pressure GaugeFLUID MECHANICS LAB

INSTRUCTOR HUSNAIN AHMED

8TH SEPTEMBER, 2014


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Content

Bourdon

Gauge

DeadWeight

Calibrator

Experim

Instruct


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INTRODUCTION

Bourdon tube gauge is device to measure and

represent applied pressure.

SENSING ELEMENT:

Consists of a twisted or curved metal tube.

The tube is constructed from a thin walled tube of

non circular cross section

REPRESENTATIVE ELEMENT:

A needle on a Gauge.


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PARTS:


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WORKING PRINCIPLE

The bourdon principle believes that a

flattened tube will reform or grow

considerably in the cross sectional

aspect when a pressure is applied. This

change can be represented by a needle

on a gauge.


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PROS & CONS

PROS:

o Cheap

o Portable

o Easy to use

o No leveling required CONS:

o Static Measurement only

o Lower accuracy.


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INTRODUCTION

A dead weight testerapparatus uses knowntraceable weights to apply pressure to a fluidchecking the accuracy of readings from a pregauge.


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PARTS Piston

The Dead Weight Calibrator accessory comprises a precision

ground piston and cylinder.

Weights

Weights may be added to the piston so that a number of

predetermined pressures may be set up within the cylinder.

Baseboard

The cylinder is mounted on a baseboard which is supported on

leveling screws and fitted with a spirit level.

Gauge Connection

The gauge under test is linked to the cylinder connection by a

flexible tube.


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WORKINGA pressure gauge could be calibrated by mounting a closed

with a piston at one end. (Such a vessel is called a dead-weigtester).

Placing a weight on the piston produces a known pressure invessel equal to the weight divided by the piston area.

After applying a series of weights and measuring the correspoutput value of the pressure gauge you can plot the relations

between the gauge reading and added weights.


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CALIBRATION OF

PRESSURE GAUGEEXPERIMENT 2


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OBJECTIVE

To calibrate a Bourdon type pressure gauge andto determine the gauge errors.

To determine the measurement errors in thereference pressure source used for calibration


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APPARATUS

Accurate weights

Bourdon Tube PressureGauge

Dead Weight Tester

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APPARATUS DEMONSTRATION

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Related Theory

A measurable reference pressure, P is generated due to the upiston and weights with the cylinder:

P=F/A (Pascals)

F=Mg

A=d2/4

F is the force applied to the liquid in calibrator cylinder

M is the total mass including piston mass

A is area of piston

EQUIPMENT SETUP


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EQUIPMENT SETUP

Note the weight of the piston (0.5kg) and individual calibration massesbefore setting the equipment.

Place the dead weight calibrator bench top and ensure that the base ishorizontal by adjusting the base using spirit level. This is necessary toensure the vertical transfer of the applied load and free rotation ofpiston.

Attach the flexible tube from the base of the cylinder to the base of theBourdon gauge.

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PROCEDURE


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PROCEDUREObserve the Pressure gauge unit setup.Be sure all hoses are attached securelyto the Bourdon gauge.

Record the gauge reading ( KN/m2) for

the unloaded piston, which correspondsto a total mass.

Place the given dead weight (0.5 Kg)one by one and record the reading ofthe gauge.

To prevent the piston from sticking,

rotate the piston gently as each mass isadded, so that the friction in the pistoncan be reduced.

Tabulate data in table & Plot thecalibration curve

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OBSERVATION & CALCULATIONS

Mass ofPiston

Mp (kg)

Diameter ofPiston d

(m)

Area ofPistonA (m 2)

Mass ofweights Mw

(kg)

TotalMass

M (kg)

Gaugereading G

(kN/m2)

Cyl inderpressure

P (kN/m 2)

Absolutegauge error

(kN/m2)

% GaugError

d2/4Mp + Mw Mg/A G P 100*(G-P

Plot a graph of gauge reading against absolute gauge error and of gauge reading against

gauge error.

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TO DO !

ASSIGNMENT SUBMISSION (FLUID MECHANICS APPLICATION)

TASK 1: LAYOUT SUBMISSION

PERFORM EXPERIMENT

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