Pressure Measurement in Ring Balance Meters

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Questions and Answers

Which equation correctly represents the relationship between the rotating moment and the restoring moment in a ring balance meter?

(P1 + P2) A r1 = r2 x M x g x Sin θ

(P1 - P2) A = r1 x r2 M g Sin θ

(P1 - P2) A x r1 = r2 x M g Sin θ (correct)

(P1 - P2) A r1 = r2 x M x g x Sin θ

What is the sealing fluid commonly used in a ring balance meter?

Glycerin

Oil

Water

Paraffin (correct)

What type of pressure does the differential pressure measurement primarily quantify?

Gauge pressure (correct)

Dynamic pressure

Absolute pressure

Vacuum pressure

What materials are typically used in the construction of bellows used in pressure measurement?

Stainless steel and copper Signup and view all the answers

In the ring balance meter, which of the following parameters is NOT included in the equation for calculating differential pressure?

Density Signup and view all the answers

What is the equivalent of 508 mm WC in inches WC?

20 inches WC Signup and view all the answers

Which pressure measurement is considered as the difference between the pressure of a fluid and absolute zero of pressure?

Absolute Pressure Signup and view all the answers

In which situation would differential pressure measurement be most appropriately used?

Measuring flow rates in pipes Signup and view all the answers

Which statement about gauge pressure is true?

It accounts for the local atmospheric pressure as a reference point. Signup and view all the answers

What device is primarily used to measure atmospheric pressure?

Aneroid Barometer Signup and view all the answers

If a tire is inflated to 200 kPa, how would this pressure be classified?

Gauge Pressure Signup and view all the answers

What type of pressure is measured as the sum of local atmospheric pressure and gauge pressure?

Absolute Pressure Signup and view all the answers

Which of the following is NOT a type of pressure measurement mentioned?

Static Pressure Signup and view all the answers

What is the primary disadvantage of using a McLeod gauge for pressure measurement?

It is unsuitable for continuous measurement. Signup and view all the answers

Boyle's Law is relevant to which type of pressure measurement?

Absolute pressure measurement. Signup and view all the answers

In the context of the McLeod gauge, what does raising the mercury level achieve?

It isolates the gas in limb B for pressure measurement. Signup and view all the answers

Which of the following correctly represents the formula for differential pressure as derived from the moments in the double bell gauge?

(P1 - P2) A x L = Mg r Sin θ Signup and view all the answers

What is the main application of the McLeod gauge?

Measuring very low absolute pressures. Signup and view all the answers

Which concept explains the relationship between pressure and volume in a gas, relevant to the operation of a McLeod gauge?

Boyle's Law Signup and view all the answers

What physical principle allows the double bell differential pressure gauge to function?

The difference in gravitational force on the bells. Signup and view all the answers

What variables influence the pressure reading on a McLeod gauge according to its formula?

Cross-sectional area, height difference, density, and gravitational acceleration. Signup and view all the answers

Study Notes

Instrument Trade Theory Notes

This document is a study guide for Industrial Instrumentation, covering topics relevant to N2, N3 and N4 students.
The guide focuses on the fundamental principles and different types of pressure and temperature measurement.
The content includes theory, diagrams, and examples for practical application, ensuring foundational knowledge.

The document provides a comprehensive list of chapters covering various instrumentation topics, and specifies the grade levels applicable to each chapter.
Included topics involve non-electrical and electrical pressure, temperature measurement, and other associated instrumentations.

Preface

The study guide's necessity arose from the growing interest in Industrial Instrumentation among students.
It aims to provide clear and concise notes to assist apprentices to understand this vast field.
The fundamental knowledge gained is essential for further studies in Instrumentation.
The document acknowledges the contributions of various individuals in its creation, including specific thanks to individuals who assisted in writing, printing and other administrative functions.

Chapter 1: Non-Electrical Pressure

This chapter covers non-electrical methods of measuring pressure.
It details the various types of manometers, including equal-leg (dry and wet), unequal-leg, and inclined manometers.
Specific instruments such as Bourdon tubes (C-type, helical, spiral), diaphragm types, ring balance meters, and bell type instruments are examined.

Units of Measurement (Chapter 1)

Provides a list of common SI and British units of measurement used in pressure measurements, and conversion factors between these.
Describes SI units and their use, alongside multiples and sub-multiples, as well as British units where applicable.
This information is also relevant to other areas.

Pressure Measurement (Chapter 1)

Defines different types of pressure: absolute, gauge, and differential pressure, and provides formulas and examples for converting units.
Explains principles of operation and calculations of different types of pressure measuring instruments including their calibration and limitations.

Chapter 2: Electrical Pressure

This chapter deals with electrical methods of pressure measurement, particularly strain gauges, focusing on N3 knowledge.
Explains different types of strain gauges (bonded, non-bonded), including grids, rosettes, helical, and foil types, along with advantages and applications.
Presents different transducers, their properties, and their uses.
Includes formulas for stress, strain, and gauge factor, along with examples to calculate the effect of applied stress on resistance change of a strain gauge.

Chapter 3: Non-Electrical Temperature

This chapter provides information on non-electrical temperature measuring instruments.
It covers various temperature scales, along with formulas for conversions between them (e.g., Celsius, Kelvin, Fahrenheit).
Explains different types of expansion thermometers (liquid, gas, vapour pressure, bimetallic) and their working principles.
Includes the principles of temperature compensation, using components such as compensating links.

Chapter 4: Electrical Temperature

This chapter deals with electrical methods of temperature measurement.
Includes resistance thermometers (formulas, materials, advantages, drawbacks).
Details operation and calculation for the Wheatstone bridge circuit, discussing balanced and unbalanced methods, as well as cold-junction compensation.
Explains thermocouples (construction, principles like Seebeck effect, types, measurement circuit use, and drawbacks).

Chapter 5: Potentiometer, Thermistors, and Pyrometers

This chapter is dedicated to potentiometer theory as well as the use of thermistors and different types of pyrometers.
It covers the design and operation of potentiometers, including zero suppression and cold junction compensation.
The chapter then moves to details of thermoelectric devices such as thermistors and different types of pyrometers (disappearing filament, wedge type, total radiation) including their advantages, disadvantages and uses.

Chapter 6: Telemetering

This chapter dives deep into the methods of transmitting measurements over distances.
It discusses pneumatic telemetering, describing various systems like flapper nozzle systems, relay valves, and continuous bleed types.
The chapter also includes details of electrical telemetering, outlining advantages, and different types such as voltage telemetering and conductance types.

Chapter 7: Automatic Control and Valves

It covers different types of automatic control systems, including pneumatic and electronic controllers.
Including, a discussion of control actions (ON/OFF, Proportional, Integral, and Derivative).
Providing details of valve types, including their principles of operation.
Providing descriptions of valve positioners and the different types of pneumatic controllers and how they operate.

Chapter 8: Flow

This chapter focuses on various flow meters and their principles.
Includes different types of meters for liquids and gases, including volumetric meters, rate of flow meters, and area flow meters (e.g., rotameters).
Discusses Bernoulli's principle and its application to flow measurement, as well as using instruments like the orifice plate, venturi tube, pitot tube, and flow nozzle.
Also includes important graphs and charts that relate flow and pressure, as well as calculating linear relationships, such as the square root problem.

Chapter 9: Level

This chapter focuses on level measurement methods.
Covers sight glass, float-operated systems, Ekstrom level meters, flow manometers, and various displacement-based and electrical methods such as capacitive, ultrasonic, and nuclear methods.

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Description

Test your knowledge on the principles of pressure measurement and the components of ring balance meters. This quiz covers topics such as moments, sealing fluids, differential pressure measurement, and the materials used in bellows. Perfect for engineering students and professionals in fluid mechanics!