PASCO Specialty & Mfg. pasco TD-8578 User's Manual
Contents
1. thermistor capture spring thermal rod Replacement Parts The following parts can be ordered from PASCO scientific Item PASCO Mod Thermistor 100k O 150 031 AL Tube 648 07139 012 07114D Thermal Expansion Apparatus Experiment Measuring the Coefficient of Linear Expansion for Copper Brass and Aluminum Introduction Most materials expand when heated through a temperature range that does not produce a change in phase The added heat increases the average amplitude of vibration of the atoms in the material which increases the average separation between the atoms Suppose an object of length L undergoes a temperature change of magnitude AT If AT is reasonably small the change in length AL is generally proportional to L and AT Stated mathematically AL aL where 0 is called the coefficient of linear expansion for the material Materials that are not isotropic such as an asymmetric crystal for example 0 can have different value depending on the axis along which the expansion is measured also vary somewhat with temperature Therefore the degree of expansion depends not only on the magnitude of the temperature change but on the absolute temperature as well In this experiment you will measure a for copper aluminum and brass These metals are isotropic so it is necessary to measure 0 along only one dimension Also within the limits of this experiment doe2. Instruction Manual and 012 07114D Experiment Guide for the PASCO scientific Model TD 8578 THERMAL EXPANSION APPARATUS 1999 PASCO scientific 4 S eq e 10101 Foothills Blvd Roseville CA 95747 7100 P teach science hone 916 786 3800 FAX 916 786 8905 www pasco com 012 07114D Thermal Expansion Apparatus Table of Contents Section Page Copyright Warranty and Equipment ii INTRODUCTION eae se Micra E a d R UE 1 Additional Equipment Required 1 Notes on Temperature 1 Accepted Values for Coefficient of Thermal Expansion Clianping Tubes Rie eee Bae G eee eae Balla 2 Replacement Parts eret tato R T icc edd 2 EXPERIMENT Measuring the Coefficient of Linear Expansion for Copper Brass and Aluminum 3 Procedure 3 Data 4 QUGSCOIDS ee teret tte fie TE m ined 5 Thermistor Conversion Table 5 Technical SUBDOEL si betae Rte Ros FoU Debes eso 7 eae i Thermal Expansion Apparatus 012 07114D Copyright Warranty and Equipment Return Please Feel free to duplicate this manual subject to the copyright restrictions bel
3. 71 6 129 8 97 126 740 20 39 605 46 14 410 72 5 936 1 98 120 810 21 37 995 47 13 897 73 5 749 3 99 115 190 22 36 458 48 13 405 74 5 569 3 100 109 850 23 34 991 49 12 932 75 104 800 24 33 591 50 12 479 76 100 000 25 32 253 51 12 043 77 PASCOL entific Thermal Expansion Apparatus 012 07114D PASCCR cie ifie 3 012 07114D Thermal Expansion Apparatus Feedback If you have any comments about the product or manual please let us know If you have any sugges tions on alternate experiments or find a problem in the manual please tell us PASCO appreciates any cus tomer feedback Your input helps us evaluate and improve our product To Reach PASCO For technical support call us at 1 800 772 8700 toll free within the U S or 916 786 3800 fax 916 786 3292 e mail techsupp pasco com web WWW pasco com Technical Support Contacting Technical Support Before you call the PASCO Technical Support staff it would be helpful to prepare the following information gt If your problem is with the PASCO apparatus note Title and model number usually listed on the label Approximate age of apparatus A detailed description of the problem sequence of events in case you can t call PASCO right away you won t lose valuable data If possible have the apparatus within reach when calling to facilitate description of individual parts gt
4. If your problem relates to the instruction manual note Part number and revision listed by month and year on the front cover Have the manual at hand to discuss your questions
5. the tube If additional data points are desired you will also need a source of hot or cold water Notes on Temperature Measurement A thermistor s resistance varies reliably with tempera ture The resistance can be measured with an ohmme ter and converted to a temperature measurement using the attached conversion table tag and also on the back page of this manual Although the relationship between temperature and resistance is not linear a linear approximation can be accurately used to interpo late between table data points with an accuracy of approximately 0 2 The thermistor used to measure the tube temperature is embedded in the thermistor lug Once thermal equilib rium has been reached the heat is highly uniform along the length of the tube The foam insulator is used to inhibit heat loss through the thermistor lug so the lug temperature closely follows the tube tempera ture The insulator does not have any appreciable effect on the local temperature of the tube itself Thermal Expansion Apparatus 012 07114D Accepted Values for Coefficient of Thermal Expansion X10 6 C Material Copper Aluminum Changing Tubes Caution When changing tubes be careful not to pull the wires off of the thermistor D Compress the capture spring by pressing the two ends together Insert the curved lug of the thermistor between the capture spring and the thermal tube Release spring
6. eam is passed through it The expansion of the metal is measured with 0 01 mm resolution using the built in dial gauge Temperatures are measured to within 0 2 using a thermistor attached to the center of the tube If you wish to investigate the expansion of the metals at additional temperatures hot or cold water can be passed through the tubes Complete step by step instructions and a data sheet for results are provided on the following pages Equipment Your TD 8578 Thermal Expansion Apparatus in cludes 40 cm long expansion base with a built in dial gauge and thermistor JNOTE The dial gauge can be removed or repositioned by loosening the set screw on the dial gauge mounting block Three metal tubes brass copper 99 596 Cu 0 5 Te and aluminum 98 9 AI 0 7 Mg 0 4 Si 6 4 mm outside diameter A foam insulator to avoid heat loss at the ther mistor connection point Thermoplastic elastometer tubing with 6 4 mm LD Additional Equipment Required In addition to the TD 8578 Thermal Expansion Apparatus the following items are needed to perform the experiment D A source of steam or hot water such as the PASCO Model TD 8556A Steam Generator A digital ohmmeter such as PASCO Model SE 9589 to measure the thermistor resistance Leads should have banana plug connectors such as PASCO Model SE 9750 or SE 9751 Patch Cords A container to catch the water as it drains out of
7. mperature Record this value in the table Use tubing to attach your steam generator to the end of the copper tube Attach it to the end closest to the dial gauge Place a container under the other end of the tube to catch the draining water Turn the outer casing of the dial gauge to align the zero point on the scale with the long indicator needle As the tube expands the indicator needle will move in a counterclockwise direction 49 Turn on the steam generator As steam begins to flow watch the dial gauge and the ohmme ter When the thermistor resistance stabilizes record the resistance R in Table 1 Also record the expansion of the tube length AL as indicated by the displacement of the indicator on the dial gauge Each increment on the dial gauge is equivalent to 0 01 mm of tube expan sion P gt Repeat the experiment for the brass and aluminum tubes Data and Calculations TABLE 1 Data and Calculations D Use the Thermistor Conversion Table on page 5 of this manual or on the tag attached to the apparatus Convert your thermistor resistance measurements and Rp into temperature measurements and T Record your results in the table hot gt Note To achieve 0 2 C accuracy for temperature you must interpolate between the temperature values listed in the Thermistor Conversion Table 012 07114D Thermal Expansion Apparatus Q Calculate AT Tx Tos Record the result in the table Using the eq
8. on notify PASCO scientific by letter phone or fax BEFORE returning the product Upon notification the return authorization and ship ping instructions will be promptly issued NOTE NO EQUIPMENT WILL BE ACCEPTED FOR RETURN WITHOUT AN AUTHORIZATION FROM PASCO When returning equipment for repair the units must be packed properly Carriers will not accept responsi bility for damage caused by improper packing To be certain the unit will not be damaged in shipment observe the following rules D The packing carton must be strong enough for the item shipped Make certain there are at least two inches of packing material between any point on the apparatus and the inside walls of the carton Make certain that the packing material cannot shift in the box or become compressed allowing the instrument come in contact with the packing carton Address PASCO scientific 10101 Foothills Blvd Roseville CA 95747 7100 Phone 916 786 3800 FAX 916 786 3292 email techsupp pasco com web WWW pasco com 012 07114D Thermal Expansion Apparatus Introduction Introduction The PASCO Model TD 8578 Thermal Expansion Apparatus provides easy and accurate measurements of the coefficient of linear expansion for brass copper and aluminum To make the measurement the brass copper or aluminum tube is placed on the expansion base The length of the tube is measured at room temperature then st
9. ow Copyright Notice The PASCO scientific 012 07114 Thermal Expansion manual is copyrighted and all rights reserved How ever permission is granted to non profit educational institutions for reproduction of any part of the manual providing the reproductions are used only for their laboratories and are not sold for profit Reproduction under any other circumstances without the written consent of PASCO scientific is prohibited Limited Warranty PASCO scientific warrants the product to be free from defects in materials and workmanship for a period of one year from the date of shipment to the customer PASCO will repair or replace at its option any part of the product which is deemed to be defective in mate rial or workmanship The warranty does not cover damage to the product caused by abuse or improper use Determination of whether a product failure is the result of a manufacturing defect or improper use by the customer shall be made solely by PASCO scientific Responsibility for the return of equipment for war ranty repair belongs to the customer Equipment must be properly packed to prevent damage and shipped postage or freight prepaid Damage caused by im proper packing of the equipment for return shipment will not be covered by the warranty Shipping costs for returning the equipment after repair will be paid by PASCO scientific Equipment Return Should the product have to be returned to PASCO scientific for any reas
10. s not vary with temperature Procedure Measure L the length of the copper tube at room temperature Measure from the outer edge of the stainless steel ring on one end to the outer edge of the stainless steel ring at the other end see Figure 1 Record your results in Table 1 Mount the copper tube in the expan sion base as shown in Figure 2 The stainless steel ring on the tube fits into the slot on the slotted mounting L block and the bracket on the tube presses against the spring arm of the dial gauge Figure 1 Measuring Tube Length Use the capture spring on stainless steel ring the expansion tube to stainless steel ring attach the thermistor lug p ls d somewhere in the middle J of the copper tube The J lug will be aligned with a7 thermistor the axis of the tube as shown in Figure 2 so there is maximum contact between the lug and the tube Figure 2 Equipment Setup Top View PAS entific slotted mounting block contact indicator Thermal Expansion Apparatus 012 07114D Place the foam insulator over the thermistor lug Plug the leads of your ohmmeter into the banana plug connectors labeled THERMISTOR in the center of the expansion base The banana plug connectors are located at one end of this unit in a stop bracket Measure and record the resistance of the thermistor at room te
11. uation AL aL AT calculate for copper steel and aluminum Questions D Look up the accepted values for the linear expansion coefficient for copper brass and aluminum Compare these values with your experimental values What is the percentage difference in each case Is your experimental error consistently high or low On the basis of your answers in question 1 speculate on the possible sources of error in your experiment How might you improve the accuracy of the experiment THERMISTOR CONVERSION TABLE Temperature versus Resistance Res Temp Res Temp Res Temp Res Temp Q CC Q CC 62 CC Q CC 351 020 0 95 447 26 30 976 52 11 625 78 332 640 1 91 126 27 29 756 53 11 223 79 315 320 2 87 022 28 28 590 54 10 837 80 298 990 3 83 124 29 27 475 55 10 467 81 283 600 4 79 422 30 26 409 56 10 110 82 269 080 5 75 903 31 25 390 57 9 767 2 83 255 380 6 72 560 32 24 415 58 9 437 7 84 242 460 7 69 380 33 23 483 59 9 120 8 85 230 260 8 66 356 34 22 590 60 8 816 0 86 218 730 9 63 480 35 21 736 61 8 522 7 87 207 850 10 60 743 36 20 919 62 8 240 6 88 197 560 11 58 138 37 20 136 63 7 969 1 89 187 840 12 55 658 38 19 386 64 7 707 7 90 178 650 13 53 297 39 18 668 65 7 456 2 91 169 950 14 51 048 40 17 980 66 7 214 0 92 161 730 15 48 905 41 17 321 67 6 980 6 93 153 950 16 46 863 42 16 689 68 6 755 9 94 146 580 17 44 917 43 16 083 69 6 539 4 95 139 610 18 43 062 44 15 502 70 6 330 8 96 133 000 19 41 292 45 14 945
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