Process Measurement Instrumentation Terms, …

1 Course 601-500 Process Measurement Fundamentals 08/01/00 Exercise 2000 Design Assistance Corporation 02-1 Exercise Measurement InstrumentationTerms, Abbreviations And DesignationsObjective Using a DAC Process Trainer (DAC Models #601, #602 and/or#603), the DAC Process Trainer Use Guide and ReferenceSchematics & Drawings, and a Process ControlInstrumentation Technology text (or an equivalent), identify thevarious concepts, terminology, abbreviations and standardindustrial designations used in the maintenance of processmeasurement Standard Identify all the italicized terms with 100% accuracy.

2 Define the term " Measurement " with 100% accuracy. State the importance of specifying the units of Measurement . List the fundamental units of Measurement in the MKS, CGS,and English Engineering systems. Draw and label a block diagram of a Basic MeasurementChannel with 100% accuracy. Contrast accurately the terms direct and inferred Measurement . Discriminate clearly between the terms range and span andbetween the terms elevated zero and suppressed zero. Define with 100% accuracy the following commonlyencountered static characteristics of a Process measurementchannel:!Accuracy!Resolution! Sensitivity!Deadband!Hysteresis!Linearit y!Conformity Given a diagram, explain the following characteristics of aninstrument channel with 100% accuracy: Course 601-500 Process Measurement Fundamentals 08/01/00 Exercise 2000 Design Assistance Corporation 02-2!

3 Dead Time!Time ConstantFoundation Competencies Knowledge of the DAC Process Trainer Use Guide terminologyand Process system construction (Exercise E601 or E602 orE603-M01).Required Background Reading Process Control Instrumentation Technology, 6th Ed. by CurtisD. Johnson, pgs. 1-46. (DAC, #584-MAN) Measurement and Control Basics, 2nd Ed. by Hughes, (DAC, #582-MAN) The Condensed Handbook of Measurement and Control, Battikha, pgs. 1-19. (DAC, #581-HBK)Tools Required Pencil and Required A DAC Process Trainer (Model #601, #602 and/or #603).Introductory DiscussionThe industrial plants of today utilize the Measurement of many parameters inorder to operate in the most efficient, effective, and reliable way possible. Conditionsare constantly monitored to provide a safe and comfortable atmosphere for theworkers in the plant and to limit emissions of hazardous materials from the plant thatcould impact the environment.

4 The Instrumentation industry has become a verydiversified field; well trained and quality instrument technicians are needed to operate,calibrate, and maintain the equipment used to measure these parameters. Toperform these tasks technicians must understand the meaning of Measurement andbe familiar with the units of Measurement . They must also be familiar with the basicconcepts and physical principles involved in detecting these parameters and theterminology used to express the parameter s characteristics and calibration of themeasuring instruments. Any number of methods and/or sensors can be used tomeasure each parameter in a Process . Course 601-500 Process Measurement Fundamentals 08/01/00 Exercise 2000 Design Assistance Corporation 02-3In this exercise you will have the opportunity to investigate the basicterminology associated with the more commonly used Measurement methods,concepts, and the principles involved, along with the fundamentals of measurementand the terms used to describe the set up, calibration and operation of the many Process applications used throughout industry.

5 It is importantthat you know how to describe the instruments and how they function, so you canevaluate their operation and repair them when StepsStep the most fundamental dimensions of Measurement . Describe what is meant by the term Measurement .gA Measurement is simply an exact comparison of a physicalquantity to some definite standard or measure of dimensioncalled a unit. Describe the importance of specifying the units of any and a physical quantity is described, the units of thestandard to which the quantity was compared must bespecified. A number alone is insufficient to describe a a number is used to describe a physical quantity, it isimportant to include, and even emphasize, the specific unitused in the Measurement , for the same physical quantity maybe measured using a variety of different units.

6 For example,length may be measured in inches, feet, yards, miles,centimeters, meters, kilometers, etc. List the three (3) most fundamental units of physical quantities can be expressed in terms of threefundamental units: (1) length, (2) mass, and (3) time. Describe what is meant by these three (3) fundamental units ofmeasurement. Course 601-500 Process Measurement Fundamentals 08/01/00 Exercise 2000 Design Assistance Corporation 02-4g Length -- is the distance from one point to Mass -- is the quantity of matter Time -- is the period during which an event occurs.

7 Describe why these three (3) units of Measurement are called Fundamental , mass, and time are called fundamental units becauseunits of most other quantities are reducible to these example, area is the product of two lengths; it has units oflength times length, or length squared. In the English system,the units of area are square feet, written ft2, or square inches,written , volume is the product of three lengths; it has units oflength cubed. In the English system, the units of volume arecubic feet, written ft3, or cubic inches, written physical quantities are also combinations of the threefundamental units. Velocity is the time rate of change ofdistance or length per unit time, thus, it has units of lengthdivided by time. In the English system, the units of velocity arefeet per second, written ft/sec, or miles per hour, written mi/hror , it can be shown that other, more complicated physicalquantities, such as horsepower, watts, and British ThermalUnits (BTUs), are all combinations of the three fundamentalunits of length, mass, and the basic systems of fundamental units ofmeasurement used throughout the Process industry.

8 List the three (3) most widely used systems of three most widely used systems of Measurement units are: Course 601-500 Process Measurement Fundamentals 08/01/00 Exercise 2000 Design Assistance Corporation 02-51. The meter-kilogram-second (MKS) system2. The centimeter-gram-second (CGS) system 3. The English system Describe the fundamental units of length, mass, and time ineach of these 1 lists the fundamental units of length, mass, and time ineach of these three 1. Fundamental Measurement UnitsUnitMKSCGSE nglishLengthmeter (m)centimeter (cm)foot (ft)Masskilogram (kg)gram (g)pound (lb)Timesecond (sec)second (sec)second (sec) Describe when and where each system is normally existence of different sets of fundamentals unitscontributes to a considerable amount of confusion in manycalculations.

9 Therefore, several years ago the United Statesattempted to adopt the more logical Metric System ( theMKS and CGS), but it has not been accepted and MKS system, with some application of the CGS system, isemployed for physics calculations. Many internationalmanufacturers use this system exclusively; some will provideboth the Metric and the English units, with the English inparentheses (..).gThe English system, however, is still often employed inengineering , in the Process Instrumentation industry it isnecessary to have some degree of understanding of all threesystems of units. Course 601-500 Process Measurement Fundamentals 08/01/00 Exercise 2000 Design Assistance Corporation 02-6 Describe the advantages of using the Metric Metric System is much simpler to use than the Englishsystem because it is a decimal system in which prefixes areused to denote powers of older, English system requires the use of conversionfactors that must be memorized and are not necessarilycategorized logically, as powers of 10 are.

10 For example, 1 mileis 5,280 feet and 1 inch is 1/12 of a foot. Table 2 lists some ofthe more common units in the English 2. Common Units in the English System12 inches (in)= 1 foot (ft)1 yard (yd)= 3 feet (ft)1 mile (mi)= 5,280 feet (ft)16 ounces (oz)= 1 pound (lb)1 ton= 2,000 pound (lb)1 minute (min)= 60 seconds (sec)1 hour (hr)= 3,600 seconds (sec)1 gallon (gal) = cubic foot (cu. ft)gThe use of the metric system is more logically arranged. Thename of the unit will also represent an order of magnitude, viathe prefix. One can tell at a glance the approximate size of ameasurement. The metric system prefixes are listed in Table 3. Table 3. Metric System PrefixesPrefixDecimallyPower of 10micro-1/1,000,00010-6milli-1/1,00010-3 centi-1/10010-2deci-1/1010-1deka-10101he kto-100102 Course 601-500 Process Measurement Fundamentals 08/01/00 ExercisePrefixDecimallyPower of 10 2000 Design Assistance Corporation 02-7kilo-1,000103mega-1,000,000106 Describe how to convert from the English System to the MetricSystem, and back to the English System.