PASCO TD-8561 User Manual

Includes

Teacher's Notes

and

Typical

Experiment Results

Instruction Manual and
Experiment Guide for

012-03349D

5/94

the PASCO scientific
Model TD-8561

THERMAL CONDUCTIVITY

APPARATUS

© 1987 PASCO scientific $5.00

012-03349D Thermal Conductivity Apparatus

T able of Contents

Section.............................................................................................................. Page

Copyright, Warranty and Equipment Return..........................................................ii

Introduction ............................................................................................................ 1

Experiment:

Measuring Thermal Conductivity..................................................................... 3

Equipment Needed ..................................................................................... 3

Data and Calculations................................................................................. 4

Teacher’s Guide...................................................................................................... 5

Technical Support....................................................................... Inside Back Cover

i

Thermal Conductivity Apparatus 012-03349D

Copyright, Warranty and Equipment Return

Please—Feel free to duplicate this manual
subject to the copyright restrictions below.

Equipment Return

Copyright Notice

The PASCO scientific Model TD-8561 Thermal
Conductivity Apparatus manual is copyrighted and all
rights reserved. However, permission is granted to
non-profit educational institutions for reproduction of
any part of this 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 this 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 material or workmanship. This 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 warranty repair belongs to the cus­tomer. Equipment must be properly packed to prevent
damage and shipped postage or freight prepaid.
(Damage caused by improper 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.

Should the product have to be returned to PASCO
scientific for any reason, notify PASCO scientific by
letter, phone, or fax BEFORE returning the product.
Upon notification, the return authorization and
shipping instructions will be promptly issued.

ä

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
responsibility for damage caused by improper
packing. To be certain the unit will not be
damaged in shipment, observe the following rules:

➀ The packing carton must be strong enough for the

item shipped.

➁ Make certain there are at least two inches of

packing material between any point on the
apparatus and the inside walls of the carton.

➂ 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: [phone]
FAX: [phone]
email: [e-mail]
web: www.pasco.com

ii

012-03349D Thermal Conductivity Apparatus

Introduction

Thermal Conductivity Apparatus

Heat can be transferred from one point to another by three
common methods: conduction, convection and radiation.
Each method can be analyzed and each yields its own
specific mathematical relationship. The TD-8561 Thermal
Conductivity Apparatus allows one to investigate the rate
of thermal conduction through five common materials
used in building construction.

The equation giving the amount of heat conducted through
a material is:

∆Q = k A ∆T ∆t / h.

In this equation,
is the area through which conduction takes place,
temperature difference between the sides of the material,
∆t is the time during which the conduction occurred and h
is the thickness of the material. The remaining term, k, is
the thermal conductivity of a given material.

The units for k depend upon the units used to measure the
other quantities involved. Some sample conversions
between different possible sets of units are shown in Table

1.

Watt cm 1.338 x 10
cm2 °K

Watt m 1.338 x 10-54.818 x 10-20.5782 6.938
m2 °K

Watt in. 9.485 x 10
in.2 °R

Cal cm 5.600 x 10
cm2 sec °K

∆Q is the total heat energy conducted, A

∆T is the

Btu in. Btu in. Btu ft Btu in.

in.2 sec °R in.2 hr °Rft2 hr °Rft2 hr °R

-2

4.818 57.82 693.8

-4

3.414 40.97 491.7

-3

20.16 241.9 2.903 x 10

The technique for measuring thermal conductivity is
straightforward. A slab of the material to be tested is
clamped between a steam chamber, which maintains a
constant temperature of 100 °C, and a block of ice, which
maintains a constant temperature of 0°C. A fixed tempera­ture differential of 100 °C is thereby established between
the surfaces of the material. The heat transferred is
measured by collecting the water from the melting ice. The
ice melts at a rate of 1 gram per 80 calories of heat flow
(the latent heat of melting for ice).

The thermal conductivity, k, is therefore measured using
the following equation:

k = (cal cm/cm

2

sec) =

(mass of melted ice) (80 cal/gm) (thickness of material)

(area of ice) (time during which ice melted) (temp.

differential)

where distances are measured in centimeters, masses in
grams, and time in seconds.

The Thermal Conductivity Apparatus includes the follow­ing equipment (see Figure 1):

• Base

• Steam chamber with hardware for mounting sample

• Ice mold with cover (Part # 648-03427)

• Materials to test: Glass, wood, lexan, masonite, and
sheet rock (The wood, masonite, and sheet rock are
covered with aluminum foil for waterproofing.)

3

Table 1

The importance of k lies in whether one wishes to conduct
heat well (good conductor) or poorly (good insulator).
Therefore, the relative size of k is of importance to
designers and builders, and should be of importance to
home owners.

Note further that choosing a material with a small value
for k does not guarantee a well-insulated structure. The
amount of heat conducted out in winter (and therefore
needing to be replaced) depends also upon three other
factors: area, thickness and temperature difference. The
same holds true for heat conducted in during the summer.

The equation for determining k is:

k =

∆Q h / A ∆T ∆t = _____

Steam
chamber
with hardware
for
mounting
sample

Figure 1 Equipment Included with the Thermal

Conductivity Apparatus

1

Base

Materials to test
(Glass, wood,
lexan, masonite,
sheet rock)

(Part# 648-03427)

Ice mold

Thermal Conductivity Apparatus 012-03349D

Notes

2

012-03349D Thermal Conductivity Apparatus

Experiment: Measuring Thermal Conductivity

EQUIPMENT NEEDED:

— Steam generator that will deliver approxi-

mately 10 grams/minute (e.g., PASCO’s

Model TD-8556 Steam Generator)
— Freezer
— Container to collect melted ice (a paper

cup is fine)

— Gram balance to weigh collected water

(you could collect the water in a graduated

flask, but your results will be less accurate)
— Container to collect condensed steam
— Grease such as petroleum jelly

("Vaseline")

Measuring Thermal Conductivity

➀ Fill the ice mold with water and freeze it. Do not freeze water with lid on jar. (A few drops of

a non-sudsing detergent in the water before freezing will help the water to flow more freely
as it melts and will not significantly effect the results.)

➁ Run jar under warm water to loosen the ice in the mold.

➤ NOTE: Do not attempt to “pry” the ice out of the mold.
➂ Measure and record h, the thickness of the sample material.

Mount the sample material onto the steam chamber as shown in Figure 2.

➃

➤ NOTE: Take care that the sample material is flush against the water channel, so water will

not leak, then tighten the thumbscrews. A bit of grease between the channel and the sample
will help create a good seal.

➄ Measure the diameter of the ice block. Record this value as d

. Place the ice on top of the

1

sample as shown in Figure 2. Do not remove the ice but make sure that the ice can move
freely in the mold. Just place the open end of the mold against the sample, and let the ice
slide out as the experiment proceeds.

(Top View)

Water channel

Container for collecting

melted ice

Ice in Mold with bare ice

against material sample

Clamps

Material

sample

Container for collecting

condensed steam

Figure 2 Experimental Setup

Steam

Generator

3

Thermal Conductivity Apparatus 012-03349D

Let the ice sit for several minutes so it begins to melt and comes in full contact with the sample. (Don't

➅

begin taking data before the ice begins to melt, because it may be at a lower temperature than 0 °C.)
Obtain data for determining the ambient melting rate of the ice, as follows:

➆

a. Determine the mass of a small container used for collecting the melted ice and record it.
b. Collect the melting ice in the container for a measured time t

(approximately 10 minutes).

a

c. Determine the mass of the container plus water and record it.
d. Subtract your first measured mass from your second to determine m

, the mass of the melted ice.

wa

➇ Run steam into the steam chamber. Let the steam run for several minutes until temperatures stablize so

that the heat flow is steady. (Place a container under the drain spout of the steam chamber to collect the
water that escapes from the chamber.)

➈ Empty the cup used for collecting the melted ice. Repeat step 7, but this time with the steam running

into the steam chamber. As before, measure and record m

, the mass of the melted ice, and t, the time

w

during which the ice melted (5-10 minutes).

➉ Remeasure the diameter of the ice block and record the value as d

DATA AND CALCULATIONS

➀ Take the average of d
➁ Use your value of d

and d2 to determine d

1

to determine A, the area over which the heat flow between the ice and the steam

avg

, the average diameter of the ice during the experiment.

avg

chamber took place. (Assume that A is just the area of the ice in contact with the sample material.)

➂ Divide m

by ta and mw by t to determine Ra and R, the rates at which the ice melted before and after

wa

the steam was turned on.
Subtract R

➃

from R to determine R0, the rate at which the ice melted due to the temperature differential

a

only.

➄ Calculate k, the conductivity of the sample:

k (cal cm/cm

2

sec) = _________

∆T = Boiling point of water (100 °C at sea level) - 0°C.

Data and Calculations Table

hd1d

2

t

a

m

wa

tmwd

avg

.

2

ARaRR

0

(R0) (80 cal/gm) (h)

(A) (∆T);

4

012-03349D Thermal Conductivity Apparatus

T eacher’s Guide

Experiment: Thermal Conductivity Apparatus

Notes on Procedure

➀ Expect 10-15% error under normal (student labora-

tory) operating conditions.

➁ Keep the ice as isolated from the surroundings as

possible. Our best results were obtained using a
PASCO styrofoam calorimeter cup as an ice mold;
however, this has the disadvantage of splitting the
cup when the water freezes. (Medium-sized
styrofoam cups also work very nicely.) Whatever
mold you use, leave it

on the ice during the experi-

ment.

Accepted Values

Substance cal•cm/cm2•sec•°C watt•m/m2•K

Masonite 1.13 x 10-

Wood (Pine) 206 - 3.3 x 10-

➂ Apply a dab of grease to the joint between the plate

and the water trough to prevent leakage. Vaseline
works well; it melts, but still seals the gap.

➃

A note about the aluminum covers on some
samples: This was found experimentally to have no
measurable effect on the conductivity of the
samples. We tested this using a glass plate which
we measured both with and without an aluminum
cover, and there was no statistically significant dif­ference between multiple readings in both states.

4

4

0.047

0.11 - 0.14

®

Lexan 4.6 x 10-

Sheet Rock 10.3 x 10-

Glass 17.2 - 20.6 x 10-

4

4

4

0.19

0.43

0.72 - 0.86

Note

Values (with the exception of Lexan) from the Handbook of Chemistry and Physics, 46th Edition, published by
The Chemical Rubber Company. Value for Lexan is from a specifications sheet provided by the manufacturer.
Values for Masonite and for Sheet Rock will vary considerably.

5

Thermal Conductivity Apparatus 012-03349D

Notes

6

012-03349D Thermal Conductivity Apparatus

T echnical Support

Feed-Back

If you have any comments about this product or this
manual please let us know. If you have any sugges­tions on alternate experiments or find a problem in the
manual please tell us. PASCO appreciates any cus­tomer feed-back. Your input helps us evaluate and
improve our product.

To Reach PASCO

For Technical Support call us at 1-800-772-8700 (toll­free within the U.S.) or [phone].

Contacting Technical Support

Before you call the PASCO Technical Support staff it
would be helpful to prepare the following information:

• If your problem is computer/software related, note:
Title and Revision Date of software.
Type of Computer (Make, Model, Speed).
Type of external Cables/Peripherals.

• 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. This makes descriptions of individual parts
much easier.

• 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.

7