THERMOCOUPLE GENERAL INFORMATIONThermocouples consist of two dissimilar metals and provide a means of sensing temperature in a variety of

processes. Temperature is the most widely measured process variable and its measurement is critical in many manu-facturing processes. We at JMS manufacture temperature probes of exceptional quality to assure this measurement isaccurate.

Thermocouples can be constructed in a variety of ways from flexible wires smaller than a human hair to ruggedsheath one half inch in diameter. They can measure temperatures from -454°F to 4200°F.

Thermocouples are low-impedance devices that work by producing electro-motive forces and these EMF’s arecorrelated to a temperature based on a curve specified for that particular thermocouple calibration. The EMF producedoccurs due to temperature gradients along the wire and not at the junction. This phenomenon can be explained in threescientific theories called the Seebeck effect, the Peltier effect, and the Thompson effect.

Three laws of thermoelectric circuits that explain thermocouple behavior are The Law of Intermediate Metalswhich explains that a circuit’s EMFs are algebraically additive unless the circuit is at a uniform temperature, The Law ofHomogeneous Metals which indicates an EMF cannot be created unless another type of metal exists in the circuit anda temperature gradient exists.

The third law is the The Law of Intermediate Temperatures. If two dissimilar homogeneous metals produce athermal EMF of X; it will remain at that number if a third material is introduced into the circuit, if both ends of that thirdmaterial are at the same temperature.

The millivolt signal produced by the thermocouple is a very, very, very low level signal. Thus, transmitting thissignal over a long distance may be difficult if any extraneous “noise” is introduced into the system. This noise may causeerrors in the EMF signal. Shielded lead wire should be used in areas with excessive “noise” to help eliminate thep r o b l e m .

The lead wire that extends from the thermocouple must match the calibration of the thermocouple. This leadwire continues to transmit the signal from the thermocouple to the instrument, and as long as it is one homogeneousmetal, it does not produce an EMF along that length even if it does experience temperature gradients.

The output of a thermocouple depends on the magnitude of the temperature difference between the measuringjunction and the reference junction. The reference junction is the cold end to which the thermocouple is connected. Whilethe hot measuring junction is stable at a given temperature, the output of the point at which the reference junction ismade must be compensated for in the instrumentation. This is accomplished through “cold junction Compensation.” Thetemperature of the cold junction is measured and calculated into the overall EMF signal to obtain the accurate hot junc-tion temperature, or the temperature of the process.22Benedict, R.P. Fundamentals of Temperature, Pressure and flow Measurement, Second Edition, Wiley, New York(1977).

THERMOCOUPLE POINTS

1. A thermocouple produces an EMF based on the composition of the two dissimilar metals only, irregardless ofthe dimension or length of the conductors.

2. No voltage is produced at the thermocouple junction, only in those portions of the sensor that are in a tem-perature gradient.

J

THERMOCOUPLE CALIBRATION INFORMATION

(J)–Iron vs Constantan (Most Common)May be used in vacuum, oxidizing, reducing, and inert atmospheres. Heavier gauge wire is recommended for longterm life above 1000°F since the iron element oxidizes rapidly at these temperatures.

(T)–Copper vs Constantan (Most Common Cold)May be used in vacuum, oxidizing, reducing, and inert atmospheres. It is resistant to corrosion in most atmos-pheres. High stability at sub-zero temperatures and its limits of error are guaranteed at cryogenic temperatures.

(K)–Chromel vs Alumel (Most Common Real Hot)Recommended for continuous use in oxidizing or inert atmospheres up to 2300°F (1260°C), especially above 1000°F. Cycling above and below 1800°F (1000°C), is not recommended due to EMF alteration from hysteresis effects. Should not be used in sulfurous or alternating reducing and oxidizing atmospheres unless protected withprotection tubes. Fairly reliable and accurate at high temperatures.

(E)–Chromel vs ConstantanMay be used in oxidizing or inert atmospheres, but not recommended for alternating oxidizing or inert atmos-pheres. Not subject to corrosion under most atmospheric conditions. Has the highest EMF produced per degreethan any other standard thermocouple and must be protected from sulfurous atmospheres.

(S,R)–Platinum vs Platinum Rhodium (Most Common Real, Real Hot)Recommended for use in oxidizing or inert atmospheres. Reducing atmospheres may cause excessive grain

growth and drifts in calibration.

(N)–Nicrosil vs Nisil (New ... Better Than “K”)May be used in oxidizing, dry reducing, or inert atmospheres. Must be protected in sulfurous atmospheres. Veryreliable and accurate at high temperatures. Can replace Type K thermocouples in many application.

(W)–Tungsten vs RheniumRecommended for use in vacuum, high purity hydrogen, or pure inert atmospheres. May be used at very high tem-peratures (2316°C), however, is inherently brittle.

0 to 15.03215.032 to 42.922

-5.341 to -2.134-3.410 to -2.1343.9967 to 19.095

0 to 11.24311.243 to 50.990

0 to 22.24822.248 to 66.559

0 to 4.60922.348 to 15.362

0 to 12.426

0 to 33.9802

0 to 37.066

±4°F±3/4%

±2%±2%

±1 1/2°F±3/4%

±2%±4°F

±3/4%

±3°F±1/2%

±2.5°F±1/4%

±2.5°±1/4%

±4°F±3/4%

±1%

±2°F±3/8%

±1%±1%

±3/4°F±3/8%

N/A±2°F

±3/8%

N/AN/A

N/AN/A

N/AN/A

±3/8%

J

T

K

E

S

R

N

W

EMF(mV)OVER TEMP.

RANGELIMITS OF ERROR

STANDARD SPECIAL

yesno

nono

noyes

nono

N/A

nono

nono

nono

nono

nono

nono

whitered

bluered

yellowred

purplered

N/A

blackred

greenred

greyred

orangered

whitered

whitered

+-

+-

+-

+-

N/A

+-

+-

+-

+-

+-

+-

IronConstantan

CopperConstantan

ChromelAlumel

ChromelConstantan

Platinel

Platinum 10% RhodiumPure platinum

Platinum 13% RhodiumPure platinum

Platinum 30% RhodiumPlatinum 6% Rhodium

NicrosilNisil

TungstenTungsten 26% Rhenium

Tungsten 5% RheniumTungsten 26% Rhenium

J

T

K

E

P

S

R

B

N

W

C

ANSI T/CCALIBRATION NAMES CONDUCTOR

IDENTIFICATIONCOLORCODING MAGNETIC

THERMOCOUPLE CALIBRATION INFORMATION

ANSIT H E R M O C O U P L E

C A L I B R AT I O NTEMP. RANGE

(°F)

32 to 53005300 to 1400

-300 to -75-150 to -75-75 to +200200 to 700

-300 to 3232 to 530

530 to 2300

-300 to 600600 to 1600

32 to 10001000 to 2700

32 to 10001000 to 2700

32 to 2300

32 to 4208

Note: To determine the limits of error in degrees C, multiply the limits of error in degrees F x 5/9.

Not ANSI

Not ANSI

Not ANSI

THERMOCOUPLE-MILLIVOLT GRAPHT=Copper vs. ConstantanE=Chromel vs. ConstantanJ=Iron vs. ConstantanK=Chromel vs. AlumelW=Tungsten vs. Tungsten 26% Rhenium (also known as

Type G)C=Tungsten 5% Rhenium vs. Tungsten 26% Rhenium

(also known as Type W5)R=Platinum vs. Platinum 13% RhodiumS=Platinum vs. Platinum 10% RhodiumB=Platinum 6% Rhodium vs. Platinum 30% RhodiumN=Nicrosil vs. NisilP=Platinel

Selection of the optimum type of thermocouple andauxiliary components for a pyrometric system is necessar-ily based on a number of variables or factors of the appli-

cation. The temperature range, EMF output, accuracyrequired, resistance to atmospheric conditions, pressureand shock are typical thermocouple systems for a givenapplication.

The following technical information is intended to serveonly as a guide for thermocouple selection. Any recom-mendation stated is based on past practices and experi-ence, and no guarantees, implied or otherwise, are madeas to optimum operation conditions.

Although some of these materials will operate at high-er temperatures than shown on the chart, they representwhat is generally conceded as the maximum reliable oper-ating temperature.

TEMP. °F

MATERIALSYMBOL

HJLOMPQRSTUV

ELEMENT CONSTRUCTION

C A L I B R AT I O NJTKE

Hoskins 2300-K

1/25”900°F300°F

1400°F1000°F1800°F

1/16”1100°F400°F

1800°F1200°F2200°F

1/8” & 3/16”1200°F

700°F2000°F1200°F2300°F

1/4”1200°F

700°F2000°F1800°F2300°F

5/16”1200°F

700°F2000°F1800°F2300°F

7/16”1200°F700°F

2100°F1800°F2300°F

SUGGESTED UPPER LIMIT FOR OUTSIDE DIAMETER

TEMPERATURE INFORMATION FOR SHEATH MATERIALSHEATH

MATERIAL304SS310SS

316LSS446SS

Inconel 600Inconel 702

PlatinumMolybdenum

TantalumTitanium

HOSKINS 2300N I C R O B E L L C

MELTINGPOINT (°F)

255025502550270025002620321647505440330025502585

MAX. TEMP.IN AIR (°F)

16502100165021002100150030001000750600

23002280

AT M O S P H E R E *ORNVORNVORNVORNVONVONVON

VNRVV

ORNVORV

*KEYO=Oxidizing R=Reducing N=Neutral V=Vacuum

For high temperature applications 1000°F to 2300°F, new proprietarymaterials have been developed to perform better than the alloys used inthe past.

U = HOSKINS 2300 : “...maintains special limits accuracyby up to 10 times longer than probes made from other cable.”

V = NICROBELL : “Sheathed Type N can be used to replace Platinum / Rhodium sensors up to a maximum continu-ous temperature of 2280°F...”

MEASURING JUNCTIONThe grounded thermocouple junction is an integral part of the thermocouplesheath tip.

Advantages:• fast response time in relation to ungrounded and isolated junctions.• protects the wires from environmental chemicals and corrosives.• prolongs the operational life of the thermocouple. Longer lifespan than the

exposed junction thermocouple.• it is recommended for high pressure applications.• it is the least expensive construction.

Disadvantages:• thermal expansion of sheath material may differ from element to cause mechan-

ical stress and work hardening of metals.• ground loops may cause interference with instruments.• faults in insulation are more difficult to detect.

The ungrounded thermocouple junction is electrically insulated and electricallyisolated from the outer sheath material. In a dual ungrounded thermocouple, onecommon junction is electrically insulated from the outside sheath.

Advantages:• the thermocouple junction is isolated from the ground.• defects in the MgO insulation can be detected by measuring resistance from

loop to sheath.• long term drift under cycling conditions is minimized.

Disadvantages:• response time is usually slower than grounded thermocouples.• more expensive than grounded thermocouples.

The exposed thermocouple junction extends beyond the protective metallicsheath.

Advantages:• recommended for measurement of noncorrosive static gas, or air.• very fast response time, faster than grounded junction.

Disadvantages:• cannot be used in an environment with a high percentage of solids, high pres-

sure, or flowing material since the junction is exposed to this environment.

Isolated thermocouple junctions are used in a dual or triple thermocouple whenthe junctions are isolated from the outer sheath material as well as from eachother.

Advantages:• the elements are insulated from ground.• performs better than ungrounded or grounded junctions in a thermal cycling

environment.

Disadvantages:• slower response time than a grounded dual thermocouple.

*For tip sensitivity information, see page 3-8.

1 12

GROUNDED JUNCTION

UNGROUNDED JUNCTION

EXPOSED JUNCTION

I S O L ATED JUNCTION

THERMOCOUPLE OPERATION AND INSTALLATION INSTRUCTIONS

Thermocouples are installed by means of compression fittings, welded 1/2” x 1/2” NPT fittings, or bayonet fittings.

Follow these instructions for installation of a thermocouple with a 1/2” x 1/2” NPT fitting:

(1) Insert thermocouple into process hole(2) Tighten probe into place by turning probe into threaded connection.

When installing a spring-loaded sensor, the wires should be disconnected from the terminal block to prevent twistingand shorting during installation.

INSTALLATION:

Place thermocouple in area not too close to heating element or direct flame.

When measuring very high temperatures, install thermocouple vertically, if possible, to avoid protection tube elementsagging.

Always use thermocouple extension wire to correlate with calibration of thermocouple and instrumentation being used.

Install thermocouple away from AC power lines, preferably more than one foot away.

Do not run thermocouple wires in the same conduit with other electrical wires.

ELECTRICAL:

Make sure the extension wire is clean so a good electrical connection will result at the terminal block. Connect the pos-itive extension wire to the positive thermocouple wire and the negative extension wire to the negative thermocouple wire.Wires are color coded for identification as follows, notice that the negative leg is always red.

POS. NEG. POS. NEG*

E purple red purple redJ white red white redK yellow red yellow (KX) redR N/A N/A green redS N/A N/A black redT blue red blue redN orange red orange red

*A tracer having the color corresponding to the positive extension may be used on the negative wire code.Occasionally, it is necessary to determine thermocouple polarity in the field. The above characteristics are helpful,along with the information on the following page.

THERMOCOUPLETYPE

EXTENSIONWIRES

OUTERJACKET

brownbrownbrownN/AN/A

brownbrown

OUTERJACKETpurpleblackyellowgreengreenblue

orange

TYPE E-The negative wire has lower resistance in ohms per foot than the positive element for the same size wire.

TYPE J-The positive element is frequently rusty and is magnetic. It has a lower resistance in ohms per foot for the same size wire.

TYPE K-The negative element is slightly magnetic. It has a lower resistance in ohms per foot for the same size pos-itive wire.

TYPE R or S-The negative wire is softer. The positive wire has a lower resistance in ohms per foot for the same sizewire.

TYPE T-The negative wire is silver in appearance. The positive wire has a lower resistance in ohms per foot for the same size wire, and is usually copper colored.

TYPE N-The positive leg has a higher resistance in ohms per foot for the same size wire.

Note: When in doubt, twist the wire together, and connect opposite ends to a volt meter. Heat the twisted end with a cigarette lighter. If the volts go up - polarity is correct ...

OPERATION:

The temperature of the connection head should be kept as near room temperature as possible to avoid errors due to theextension wires. The maximum recommended temperature at the terminal block is 400°F.

MAINTENANCE:

The quality and frequency of calibration checks must be determined for each individual application by noting the decal-ibration rate of each thermocouple at individual installations. Thermocouples will deteriorate due to contamination fromtheir environments. Calibration is usually made by comparison with a working standard. The thermocouple may beremoved from its installation and checked in an electric furnace with the working standard; however, check the thermo-couple in its installed position and location if possible. See page VI.

Return thermocouples that were removed for tests to the same location and immersion depth for reliable and repeatablereadings.

Do not use a thermocouple to measure a very low temperature if it has been used to measure a very high temperaturepreviously.

Make sure protection tubes and thermowells are in good condition when protecting thermocouples with them.

Do not run a single thermocouple to two different instruments. This can result in instrument imbalance. A dual isolatedthermocouple should be used instead.

STORAGE:

Store in a clean dry place. Avoid stacking probes in areas of excessive moisture or humidity (ie: dripping, condensation).Special packing with desiccant can be specified. (See page II)

TYPE N THERMOCOUPLE VERSUS TYPE K THERMOCOUPLEIN A BRICK MANUFACTURING FACILITY

The following paper was presented by Barbara Hudson, former General Manager of JMS Southeast, Inc., at the BrickPlant Forum Convention at Clemson University in Clemson, South Carolina.

ABSTRACT:

The brick industry historically has had the option of a Type K thermocouple, which is inaccurate yet inexpensive, versusType R and S thermocouples which are very expensive yet accurate. This article investigates the Type N thermocouplewhich has been developed as a substitute for the Type K thermocouple in the 32°F to 2300°F temperature range.

TYPE K VERSUS TYPE R OR S THERMOCOUPLE

Through the years, many changes have occurred in the firing of structural clays including gas, oil, and sawdust com-bustion. Yet, the temperature measuring methods has remained the same as far as thermocouple configurations areconcerned. Throughout history, a Type K thermocouple has been used in an area which was thought of as being “non-critical”. The Type R or S thermocouples (platinum-rhodium) have been used in the past in “control” areas. The reasonsfor these uses include: Type K thermocouples, but are also less stable and less accurate. Type K thermocouples areeasily attainable, however, and widely accepted in all industries.

The reasons for the instability in Type K thermocouples are due to some inherent properties in the chromel/alumel mate-rial. One problem that occurs with this thermocouple is an effect called short-range ordering. It occurs in a temperaturerange of about 500°F to 1020°F when nickel and chromium atoms in the chromel leg tend to form an ordered crystallinestructure. The ordering produces a different metallurgical structure and if a temperature gradient exists, an erroneousEMF is produced.

Another shortcoming of Type K thermocouples is the hysteresis effect that occurs when a Type K thermocouple is cycledup and down in temperatures above and below 1800°F. The re-ordering of the crystalline structure changes with eachcycle. After the first pass above this temperature, the Type K temperature indication will probably be accurate. However,with each additional cycle after this one, the error will increase more and more. The Type K thermocouple also experi-ences a cumulative drift after a period of time at temperatures above 1650°F. Finally, this thermocouple experiences aphysical defect called “green rot” which is caused due to preferential oxidation of the chromel leg.

Even with these problems of instability and lack of longevity in Type K thermocouples, they are widely used and accept-ed in the brick industry as well as other industries. This is due to the fact that they are inexpensive and the choices havebeen limited in the past to a thermocouple that could replace Type K at a comparable price.

The platinum-rhodium thermocouples (Type R and S) on the other hand have been used as control thermocouples in thepast. They are much more stable than the Type K thermocouples, but much more expensive also. They can be tentimes the expense of a Type K thermocouple. Type R or S thermocouples do, however, after a period of time at elevat-ed temperatures, experience a drift due to platinum migration.

In essence, for temperature measurement in a brick kiln, we have a fairly accurate option at a high cost versus an unsta-ble and “short life” option at a reasonable cost. A compromise was needed!

TYPE N THERMOCOUPLES

Noel Burley, from Australia, began extensive research on a type N thermocouple (nisil/nicrosil). The composition of thisthermocouple is the following: Nicrosil-NI-14.2%, Cr-1.4%, Si and Nisil-Ni-4.4%, Si-.1%, Mg. Noel Burley’s researchshowed that the Type N thermocouple exhibited thermal stability above 1650°F, while Type K thermocouples showed a

gradual and cumulative drift. He also showed the Type N thermocouple showed no short-term change due to crystalrestructuring that occurred with the Type K thermocouple. Also, the Type N had superior resistance to oxidation (no“green rot”) and could replace the Type K throughout its entire range of 32°F-2300°F. Its cost is about the cost of a TypeJ thermocouple. Due to this information, we decided to experiment with the Type N thermocouple in a brick manufac-turing environment.

EXPERIMENTATION:

Frank Todd and Frank Todd, Jr., at Fletcher Brick were kind enough to allow us to do some experimentation in their facil-ity. We were restricted to a short time frame, so we needed accelerated life data on comparisons between a Type K andType N thermocouple. In communication with Fletcher Brick, a top to bottom and side to side temperature gradient wassuspected in their tunnel kiln. They desired better monitoring to attain better control, thus better brick. If they were togo to platinum/rhodium thermocouples as side port monitoring sensors, the thermocouples alone would have cost inexcess of $6,000 not including the data logger needed for data collection. Due to accelerated life data needed, we used20 gauge thermocouples realizing they would deteriorate quickly. Stage 1 of our experimentation included manufactur-ing 10 dual thermocouples which consisted of one 20 gauge Type K and one 20 gauge Type N thermocouple in eachsensor. These were installed in side ports of the kiln and ran for 30 days. The Type R thermocouples existed in the topcenter of the kiln as control thermocouples. All monitoring thermocouples were connected to a 40 channel data loggerwhich printed the temperature of all sensors every six hours. This data was converted to actual temperatures for theType N thermocouples and was compared to the control Type R sensors for kiln changes. After all the data was com-piled, the drift was plotted for four Type K thermocouples. The drift of the Type K thermocouple was difficult to predict.All four sensors drifted in non-repeatable and inconsistent patterns.

The Type N readings were graphed and they also failed within the 30 day period as was predicted since 20 gauge wirewas used. The drift, however, was more predictable. This was only a preliminary stage of our experimentation. We willcontinue our work with the 14 gauge Type N versus Type K thermocouples.

CONCLUSION:

In conclusion, Type N thermocouples can be used in all areas of the brick; i.e. traveling thermocouples, air conditioningvents, kiln control, monitoring sensors, and drying sensors.

Research has shown Type N thermocouples have better thermal stability than Type K in the temperature range of1200°F-1400°F, which is the pre-heat zone where carbon burn-out occurs.

Also better control can be obtained with a Type N thermocouple at the quartz inversion point of 1050°F.

Two or three different types of thermocouples used in a single plant within the Type N temperature range of 32°F-2300°Fcan be replaced by the Type N thermocouple. This would standardize the plant with one type of thermocouple enablingthe use of one type of controller, one type of data logger, etc.

This thermocouple is also ASTM certified. It has been given a color code of orange/red. It is listed in most thermo-couple manufacturers catalog. We at JMS Southeast, Inc., will continue doing research with the Type N thermocouplein structural clay firing applications.

REFERENCES:

1. Brick Association of North Carolina (Marion Cochran).2. The Nicrosil versus Nisil Thermocouple: Properties and Thermoelectric reference Data - NBS Monograph 161.3. Temperature Sensors Product Information Bulletin (TS-02) by R. Kampion of Leeds and Northrup.

TYPE N THERMOCOUPLE GENERAL INFORMATION________________________________________________________________________

COMPOSITION: Nisil/Nicrosil

Nisil: Ni-4.4 wt% Nicrosil: Ni-14.2 wt%Si-0.1 wt% Cr-1.4 wt%Mg Si

________________________________________________________________________

Color Code Magnetic

Nisil: (N) Red No

Nicrosil:(P) Orange No

________________________________________________________________________

ACCURACY:32°F to 2300°, ± 4° or .75% of temperature reading. Can replace Type “K” thermocouples throughout entire range.

Type “N” is available in beaded assemblies or sheath material. Extension wire and other temperature accessories suchas meters, controllers, transmitters, etc., are also available.

ADVANTAGES:1. Superior thermal stability at temperatures over 1650°F, while other thermocouples such as Type “K” exhibit much

greater cumulative drift.

2. Superior thermal stability in that no short term change occurs due to the crystal restructuring.

3. Superior resistance to oxidation. (No green rot.)

4. Does not exhibit hysteresis effect as the Type “K” thermocouple does.

3024201614

700°F800°F

650°F700°F

400°F400°F

400°F400°F

1300°F1500°F

600°F700°F

1400°F1600°F

700°F800°F

900°F1000°F

1600°F1800°F

800°F900°F

400°F500°F

1100°F1200°F

1700°F2000°F

900°F1100°F

500°F600°F

1100°F1200°F

1700°F2000°F

900°F1100°F

600°F700°F

1400°F1600°F

2000°F2300°F

1200°F1400°F

8

-2400 F

-2700 F

--

-2800 F

--

--

--

BareProtected

BareProtected

BareProtected

BareProtected

BareProtected

Material

Chromel andAlumel

Chromel andConstantan

Iron andConstantan

Copper andConstantan

CoupleCondition

.7031

.7187

.7344

.75

.7656

.7812

.7969

.8125

.8281

.8437

.8594

.875

.8906

.9062

.9219

.9357

.9531

.9687

.95441.00

45/6423/3247/643/4

49/6425/3251/6413/1653/6427/3255/647/8

57/6429/3259/6415/1661/6431/3263/64

1

.3594

.375

.3906

.4062

.4219

.4375

.4531

.4687

.4844

.5

.5156

.5312

.5469

.5625

.5781

.5937

.6094

.625

.6406

.6562

.6719

.6875

23/643/8

24/6413/3227/647/16

39/6415/3231/641/2

33/6417/3235/649/16

37/6419/3239/645/8

41/6421/3243/6411/16

DECIMAL EQUIVALENT CHART

INCHFRACTION

DECIMALEQUIV.

INCHFRACTION

DECIMALEQUIV.

INCHFRACTION

DECIMALEQUIV.

1/641/323/641/165/643/327/641/8

9/645/3211/643/16

13/167/32

15/641/4

17/649/32

19/645/16

21/6411/32

.0156

.0312

.0469

.0625

.0781

.0937

.1094

.125

.1406

.1562

.1719

.1875

.2031

.2187

.2344

.25

.2656

.2812

.2969

.3125

.3281

.3437

THERMOCOUPLE TEMPERATURE LIMITS

SRT

J

K

E

Platinum andPlatinum-Rhodium

AWG

NOMINAL PHYSICAL PROPERTIES OF ELEMENT

Melting Point (°C) 1535 1083 1430 1410 1870 1850 1210 1400 1773 1400

Electrical ResistivityOhms/CMF @ 20°C 60.14 10.37 425 .560 294 177 63.80 .220

Thermal ConductivityWatts/cm/°C @ 100°C .662 3.88 .192 .031 .212 .297 .695 .055

Specific HeatCal./GM/°C @ 20°C .1065 .0921 .107 .011 .094 .125 .0324 .012

Density-lb/In3 .2840 .3233 .3154 .322 .3107 .7750

Tensile StrengthAnnealed-PSI 50,000 35,000 95,000 110,00 60,000 85,000 95,000

Magnetic Strength@ 20°C Strong None None None None None None None Strong None

Specific Gravity 7.86 8.92 8.73 .852 8.9 8.60 21.45 .870

Property J T K,E N+ R S J,T,E K R,S N-Positive (+) Conductors Negative (-) Conductors

Thermoelement Material

TABLE 1. Characteristics Compositions of Thermoelement Alloys.

CHEMICAL composition (weight %)

Alloy Cr Si Mg Mn Al Fe Co C Cu Ni

nicrosil 14.2 1.4 - - - 0.1 - .03 - bal.nisil - 4.4 0.1 - - 0.1 - - - bal.

type 9.3 0.5 - 0.5 - 0.5 0.5 - - bal.(or EP)

type KN - 1.1 - 2.8 1.9 0.5 0.5 - 0.5 bal.type JP - - - .25 - bal. - - .12 -type JN - - - .75 - 0.3 0.3 - bal. 44.5type TP - - - - - - - - 99.95 -type TN - - - 0.1 - 0.1 - - bal. 45

(or EN)

RTD STANDARDSMaximum Operating Range = -195°C to 660°C (-383°F to 1475°F)Note: RTD’s are not commonly used above 900°F. However, JMSoffers a special high temperature RTD which will withstand temper-atures up to 1560°F.

Interchangeability = ±.25°C at 0°C

Stability = Less than .05°C shift per year.

Nominal Operating Current = 1 milliampere.

Maximum Safe Current = 20 Milliamperes.

Insulation Resistance = 100 mega ohms minimum at 50 VDC.

Probe Encapsulation = High purity alumina oxide.

Time constant for RTD element without tubing = 1 second maxi-mum for the sensor to reach 63.2% of a step change in tempera-ture in water at 3 feet per second.

RTD probes will usually not have a transition if the lead wires areless than 12” in length.

AccuracyThe standard accuracy of JMS Southeast’s RTD is .1% of resis-tance at 0°C . Accuracies of .03% and .01% of resistance at 0°Care also available.

StabilityJMS Southeast bulbs are aged as part of the manufacturingprocess, thus ensuring high levels of stability. Generally the resis-tance at 0°C will hold less than a .05°C shift per year.

VibrationJMS detectors can withstand a vibration level of 30g over the fre-quency range 10 Hz to 1 KHz.

PressureJMS RTD’s are insensitive to large changes of pressure.

Response TimeResponse time of JMS Southeast metal encapsulated probes isdependent on the outside diameter of the probe and the immersionmedia, usually matches that of the same size ungrounded thermo-couple. (See page 1-13)

Self HeatingWhen tested in accordance with requirements of BS 1904: 1964Section 3.16 the indicated temperature rise in the temperaturedetector with a power of 10.0mW dissipated in it, will not exceed+.3°C.

RESISTANCE TEMPERATURE DETECTORS

General Information

A resistance temperature detector or platinum resistance thermometer works on the principle that the electricalresistance of a metal changes in a significant and repeatable way when temperature changes. This resistance isinversely proportional to cross sectional area and proportional to length.

Platinum is the most widely used metal for resistance temperature detection due to the following characteristics:

1) chemical inertness2) a temperature coefficient of resistance that is large enough to give readily

measurable resistance changes with temperature3) an almost strain free fabrication metal (in that resistance doesn’t drastically

change with strain)4) an almost linear relation between resistance and temperature

Each resistance versus temperature relation for an RTD is qualified by a term known as “alpha”. “Alpha” is theslope of the resistance between 0°C and 100°C. This is also referred to as the temperature coefficient of resistance,with the most common being 0.00385Ω/Ω/°C.

Other types of RTD’s manufactured include copper, nickel and nickel alloys.

The amount of resistance of an individual RTD bulb (100Ω, 200Ω, etc.) is determined by the amount of metalbetween the terminal points and by the configuration of the element.

When ordering an RTD, the alpha and resistance value at 0°C (i.e.: Ro) must be specified to match the mea-suring instrumentation used with the RTD.

The RTD standard must also be specified. There are several RTD standards set by various organizations.These specifications are not identical and read out instrumentation must be adjusted for the specific standard of the RTDused with that equipment. Differences in the alpha values of these standards can cause errors in measurement of anRTD if one standard is connected to the instrumentation of another standard.

The following chart indicates some common RTD standards.

NOMINALRESISTANCE(ohms)

ORGANIZATION STANDARD ALPHA AT 0°C

American Scientific Apparatus RC21-4-1966 0.003923 98.129Makers Association (SAMA)

British Standards Association B.S. 1904-1964 0.003850 100

FachnormenausschuB DIN 43760 0.003850 100Elektrotchnek im DeutschenNormenausschuB

International Electrotechnical IEC 751: 1983 0.003850 100Commission (Supersedes BS & DIN)

US Department of Defense MIL-T-24388 0.00392 100

B k T H T bl Of C t t Ch t 1 10 O d F

Tolerance

RESISTANCE TEMPERATURE DETECTORS

Super DIN-Meets DIN 43760, I.E.C. 751 .00385 ohms/ohms/°C, to1/10 design tolerance at initial bulb calibrationNot available in dual element swaged-Tip sensitivity = 1 Ø + 1/2”-Probe can be manufactured as a 3/32”, 1/8”, 1/4” or larger tube

3 11

±0.9 2.25

±0.8 2.0

±0.7 1.75

±0.6 1.5

±0.5 1.25

±0.4 1.0

±0.3 .75

±0.2 .5

±0.1 .25

-200 -100 0 100 200 300 400 500

ohms °C

Standard ToleranceDIN 43760, IEC 751(0.1% at 0C)*

(0.03% at 0C)*

Super DIN(0.1% at 0C)*

Temperature °C *Initial Calibration Accuracy

THERMOCOUPLES VS RTD’S

THERMOCOUPLE RTD’S

Accuracy Limits of error wider than Limits of error smaller thanRTD thermocouples

Ruggedness Excellent Sensitive to strain, shock,and pressure

Temperature -400° to 4200°F -200° to 1475°F

Size Can be as small as .01” Size limited to 1/16”, temperaturesheath material, tip sensitive for length of bulbsensitive

Drift Should be checked 0.01 to 0.1°C per year, lessperiodically, higher than drift than thermocoupleRTD’s

Resolution Must resolve millivolts per Ohms per degree, much higherdegree, lower signal to signal to noise ratio thannoise ratio thermocouple

Cold Required Not requiredJunctionReference

Lead wire Must match lead wire Can use copper lead wire forcalibration to thermocouple extension wirecalibration

Response Can be made small enough Thermal mass restrictsfor millisecond time to seconds or moreresponse time

Cost Low Higher than thermocouples

The following chart indicates some inherent advantages and disadvantages of RTD’s or thermocouples.

LEADWIRE CONFIGURATION EXPLANATION

RED

SYMBOL Z2 WIRE CONFIGURATION

Figure 1

WHITE

RED

SYMBOL Y3 WIRE CONFIGURATION

Figure 2

WHITE

RED

RED

SYMBOL WSTANDARD4 WIRECONFIGURATION

WHITE

RED

WHITE

In the three wire configuration, the power supply is taken to one side of the resistance temperature detector. Thisputs the other two leadwires in opposite arms of the wheatstone bridge so that they cancel each other out and have lit-tle effect on the bridge output voltage. In the 3 wire configuration, the resistance of the lead wire length is compensat-ed for in the Wheatstone bridge. This design is recommended for most industrial applications.

An even more accurate wire configuration is the 4 wire design. In this design, leadwires #1 and #2 are on one sideof the power supply while leadwires #3 and #4 are on the other side of the power supply. All four leadwire resistancesin this case are negated and the bulb resistance stands as the resistance input alone. We strongly recommend thisdesign. You must have a good 4 wire input device. Call us for recommendations.

BLUE

SYMBOL VUNCOMMON4 WIRECONFIGURATION

BLUE

RED

WHITE

Figure 3

JMS RTD color codes are per ASTM E1137 and IEC 751 specifications.

A resistance temperature detector determines the temperature by measuring resistance. The sensing element isusually a small diameter wire manufactured so that its resistance will change in a known and consistent manner. Tomeasure the resistance accurately and consistently, other extraneous resistances must be compensated for or mini-mized. A major cause of extraneous resistance is leadwire in series with the RTD. The readout is the sum of the bulbresistance and the leadwire resistances. The leadwire resistance can be compensated in most applications by a threewire RTD leadwire configuration.

RTD OPERATION AND INSTALLATION INSTRUCTIONS

RTD’s are installed by means of compression fittings, welded or spring-loaded NPT fittings, or bayonet fittings.

Follow these instructions for installation of an RTD with a 1/2” x 1/2” NPT fitting:

(1) Insert RTD into process hole or opening.

(2) Tighten probe into place by turning probe into threaded connection.

If cold-end termination of the RTD is wired into head and you have a spring loaded fitting, then the wires should be dis-connected from the terminal block to prevent twisting and shorting.

ELECTRICAL:Make sure the extension wire is clean so that a good electrical connection will result at the terminal block. We

recommend the use of a lacquer, cement, or other moisture proof sealing to prevent oxidation and the loosening of ter-minals. Connect the positive extension wire to the positive RTD wire and the negative extension wire to the negativeRTD wire. Wires are color coded for identification as follows:

Two Wire Configuration:Connect the white wire to the positive connection terminal and connect the red wire to the negative connection terminal.

Three Wire Configuration:The two red wires are common. Connect the white wire to the positive connection terminal and the two red wires to thenegative connection terminals. The second red wire is the compensating lead wire.

Four Wire Configuration:The two white wires are common and the two red wires are common. Connect the two red wires to the negative con-nection terminals and the two white wires to the positive connection terminals.

RED

WHITE

RED

WHITE

RED

RED

WHITE

RED

WHITE

TEMPERATURE vs RESISTANCE TABLE

134.70172.16208.46243.61277.60310.43342.10

130.89168.47204.88240.15274.25307.20338.99

127.07164.76201.30236.67270.89303.95335.86

123.24161.04197.70233.19267.52300.70332.72

119.40157.32194.08229.69264.14297.43329.57

115.54153.57190.46226.18260.75294.16326.41

111.67149.82186.82222.66257.34290.87323.24

107.79146.06183.17219.13253.93287.57320.05

103.90142.28179.51215.58250.50284.26316.86

100.00138.50175.84212.03247.06280.93313.65

14.3656.1396.07(10)

10.4152.0492.13(20)

47.9388.17(30)

43.8084.21(40)

39.6580.25(50)

35.4876.28(60)

31.2872.29(70)

27.0568.28(80)

22.7864.25(90)

18.5360.20100.00

0

-200-100

0

(-30) (-40) (-50) (-60) (-70) (-80) (-90)(-20)(-10)

Din 43760, IEC 751 100Ω Platinum RTDAlpha=.00385

JMS TYPE E, P, STemp.

(degrees C) 0

0100200300400500600

NOTE: Due to the interchangeability tolerance of the RTD’s, the JMS type E matches bothDIN 43760 / IEC 751, and British Standard BS 1904 curves.

134.70172.16208.46243.61277.64310.51342.20

130.89168.46204.88240.16274.29307.27339.10

127.07164.76201.29236.68270.94304.02335.90

123.24161.04197.69233.19267.56300.76332.80

119.40157.31194.07229.69264.17297.50329.60

115.54153.57190.45226.18260.77294.22326.50

111.67149.82186.82222.66257.37290.93323.31

107.79146.06183.16219.12253.95287.67320.12

103.90142.29179.50215.58250.52284.31316.93

100.00138.50175.83212.02247.08280.98313.72

14.4056.2196.09(10)

10.4552.1292.16(20)

48.0188.23(30)

43.8884.29(40)

39.7280.32(50)

35.5476.34(60)

31.3472.35(70)

27.1168.34(80)

22.8364.32(90)

18.5660.28100.00

0

-200-100

0

(-30) (-40) (-50) (-60) (-70) (-80) (-90)(-20)(-10)

BS 1904, 100Ω Platinum RTDAlpha=.00385JMS TYPE E

Temp.(degrees C) 0

0100200300400500600

NOTE: Due to the interchangeability tolerance of the RTD’s, the JMS type E matches bothDIN 43760 / IEC 751, and British Standard BS 1904 curves.

TEMPERATURE vs RESISTANCE TABLE

132.83170.29206.60241.77275.78308.65

129.02166.06203.02238.30272.43305.42

125.20162.89199.43234.83269.07302.17

121.37159.17195.83231.34265.70298.91

117.52155.44192.22227.84262.32295.64

113.67151.70188.58224.33258.92292.36

109.80147.95184.95220.80255.51289.07

105.92144.19181.30217.27252.09285.76

102.03140.41177.64213.73248.66282.45

98.13136.63173.97210.17245.22279.12311.88

54.3494.22(10)

50.2690.29(20)

46.1586.36(30)

42.0282.41(40)

37.8778.44(50)

33.6974.47(60)

29.4870.47(70)

25.2466.47(80)

20.9762.44(90)

16.6758.4098.13

0

-200-100

0

(-30) (-40) (-50) (-60) (-70) (-80) (-90)(-20)(-10)

SAMA RC21-4 1966, 98.13Ω Platinum RTDAlpha=.003923JMS TYPE F

Temp.(degrees C) 0

0100200300400500600

135.30173.40210.31246.05280.61313.99

131.42169.64206.68242.53277.21310.71

127.54165.87203.03239.00273.80307.41

123.64162.09199.36235.46270.37304.10

119.73158.30195.69231.90266.93300.78

115.81154.49192.00228.33263.48297.45

111.87150.68188.30224.75260.02294.11

107.93146.85184.60221.16256.55290.75323.78

103.97143.01180.87217.56253.06287.38320.53

100.00139.16177.14213.94249.56284.00317.27

55.4392.03(10)

51.2892.03(20)

47.1088.02(30)

42.9084.00(40)

38.6779.97(50)

34.4175.92(60)

03.1271.86(70)

25.8067.78(80)

21.4463.68(90)

17.0559.57100.00

0

-200-100

0

(-30) (-40) (-50) (-60) (-70) (-80) (-90)(-20)(-10)

JISC 1604-1981, 100Ω Platinum RTDAlpha=.003916JMS TYPE G

Temp.(degrees C) 0

0100200300400500600

135.33173.48210.45246.25280.88314.33346.61

131.45169.72206.80242.72277.463011.04343.44

127.56165.94203.15239.19274.04307.73340.25

123.66162.16199.48235.63270.61304.42337.05

119.75158.36195.80232.07267.16301.09333.84

115.82154.55192.11228.50263.71297.75330.62

111.88150.73188.41224.91260.24294.40327.38

107.93146.90184.69221.31256.76291.03324.14

103.97143.06180.97217.70253.27287.66320.88

100.00139.20177.23214.08249.76284.27317.61

96.02(10)

92.02(20)

88.01(30)

83.99(40)

79.96(50)

75.91(60) (70) (80) (90)

100.000

0

(-30) (-40) (-50) (-60) (-70) (-80) (-90)(-20)(-10)

Laboratory Grade, 100Ω Platinum RTDAlpha=.00392JMS TYPE J

Temp.(degrees C) 0

0100200300400500600

NOTE: Based on NIST Supplementary ITS-90. These values were available at time if publication but subject to approval byASTM as laboratory grade.

135.17173.14209.93245.56280.01313.29

131.31169.39206.31242.05276.62310.01

127.44165.64202.67238.52273.21306.73

123.55161.87199.02234.99269.79303.43

119.66158.09195.35231.45266.37300.12332.70

115.75154.30191.68227.89262.93296.79329.49

111.83150.50188.00224.32259.48239.46326.27

107.90146.68184.30220.74256.01290.11323.04

103.96142.86180.59217.15252.54286.76319.80

100.00139.02176.87213.55249.05283.39316.55

96.03(10)

92.06(20)

88.06(30)

84.06(40)

80.04(50)

76.01(60)

71.96(70)

67.89(80)

63.80(90)

59.69100.00

0

-1000

(-30) (-40) (-50) (-60) (-70) (-80) (-90)(-20)(-10)

TEMPERATURE vs RESISTANCE TABLE

ADDITIONAL RTD ELEMENT TYPES

The following are available in addition to the RTD element types listed on page 3-1.Elements may be specified with an “X” in the part number.

ALPHA RESISTANCE VALUE TOLERANCE

Platinum - 0.003750 1000 ohms @ 0 deg. C ±0.2%Platinum - 0.003850 10 ohms @ 0 deg.C ±0.2%Platinum - 0.003850 10 ohms @ 20 deg. C ±0.2%Platinum - 0.003850 10 ohms @ 25 deg. C ±0.2%Platinum - 0.003850 20 ohms @ 0 deg. C ±0.2%Platinum - 0.003850 50 ohms @ 0 deg. C ±0.2%Platinum - 0.003850 200 ohms @ 0 deg. C ±0.1%Platinum - 0.003850 500 ohms @ 0 deg. C ±0.1%Platinum - 0.003850 1000 ohms @ 0 deg. C ±0.1%Platinum - 0.003900 100 ohms @ 0 deg. C ±0.2%Platinum - 0.003900 130 ohms @ 0 deg. C ±0.1%Platinum - 0.003910 8 ohms @ 0 deg. C ±0.5%Platinum - 0.003910 10 ohms @ 0 deg. C ±0.5%Platinum - 0.003910 32 ohms @ 0 deg. C ±0.5%Platinum - 0.003910 98.129 ohms @ 0 deg. C ±0.1%Platinum - 0.003910 100 ohms @ 0 deg. C ±0.5%Platinum - 0.003910 500 ohms @ deg. C ±0.5%Platinum - 0.003920 100 ohms @ 0 deg. C ±0.1 deg. CPlatinum - 0.003920 200 ohms @ 0 deg. C ±0.1 deg. CPlatinum - 0.003920 500 ohms @ 0 deg. C ±0.1 deg. CPlatinum - 0.003926 25.5 ohms @ 0 deg. C ±0.1%Platinum - 0.003926 100 ohms @ 0 deg. C ±0.5%Platinum - 0.003926 200 ohms @ 0 deg. C ±0.5%Platinum - 0.003926 470 ohms @ 0 deg. C ±0.5%Platinum - 0.003926 500 ohms @ 0 deg. C ±0.5%Nickel - N/A 110 ohms @ 0 deg. C ±0.5%Ni Fe - N/A 1000 ohms deg. @ 21.1 deg. C ±0.5%Ni Fe - N/A 2000 ohms @ 21.1 deg. C ±0.5%Copper - N/A 100 ohms @ 25 deg.C ±0.2%

Uncommon American 100Ω Platinum RTDAlpha=.003902JMS TYPE H

Temp.(degrees C) 0

0100200300400500600

9

1.0091.5131.9252.3362.745

3.1533.5593.9644.3664.768

5.1685.5665.9626.3586.751

7.1427.5297.9158.3018.687

9.3839.769

10.15510.54110.927

11.31311.70012.08612.47212.858

13.24413.63114.01714.40314.789

15.17815.56815.95716.34716.737

17.12717.51617.90618.29618.68718.077

8

1.1401.5541.9672.3772.786

3.1943.6004.0044.4074.808

5.2085.6066.0026.3976.790

7.1817.5687.9548.3408.726

9.3449.73010.11610.50210.889

11.27511.66112.04712.43312.820

13.20613.59213.97814.36414.751

15.13915.52915.91816.30816.698

17.08817.47717.86718.25718.64818.038

7

1.1821.5962.0082.4182.827

3.2343.6404.0444.4474.848

5.2475.6456.0426.4366.830

7.2207.6067.9928.3788.765

9.3059.69210.07810.46410.850

11.23611.62212.00912.39512.781

13.16713.55313.94014.32614.712

15.10015.49015.87916.26916.659

17.04917.34817.82818.21818.60818.999

6

1.2231.6372.0492.4592.868

3.2753.6814.0854.4874.888

5.2875.6856.0816.4766.869

7.2587.6458.0318.4178.805

9.2679.653

10.03910.42510.811

11.19811.58411.97012.35612.742

13.12913.51513.90114.28714.673

15.06115.45115.84016.23016.620

17.01017.39917.78918.17918.56918.960

5

1.2651.6782.0902.5002.909

3.3163.7214.1254.5274.928

5.3275.7256.1216.5156.908

7.2967.6838.0708.4568.842

9.2289.61410.00010.38710.773

11.15911.54511.93112.31812.704

13.09013.47613.86214.24814.635

15.02215.41215.80216.19116.581

16.97117.36017.75018.14018.53018.921

4

1.3061.7192.1312.5412.949

3.3563.7624.1654.5674.968

5.3675.7646.1606.5546.947

7.3357.7228.1088.4948.881

9.1899.5769.96210.34810.734

11.12011.50711.89312.27912.665

13.05113.43713.82414.21014.596

14.98415.37315.73616.15216.542

16.93217.32117.71118.10118.49118.882

3

1.3481.7612.1722.5822.990

3.3973.8024.2064.6085.008

5.4075.8046.2006.5946.986

7.3747.7618.1478.5338.919

9.1519.5379.92310.30910.696

11.08211.46811.85412.24012.627

13.01313.39913.78514.17114.557

14.94515.33415.72416.11316.503

16.89317.28317.67218.06218.45218.843

2

1.3891.8022.2132.6233.031

3.4373.8424.2464.6485.048

5.4465.8446.2396.6337.025

7.4137.7998.1858.5729.958

9.1129.4989.88510.27110.657

11.04311.42911.81612.20212.588

12.97413.36013.74614.13314.519

14.90615.29515.68516.07416.464

16.85417.24417.63318.02318.41318.804

1

1.4301.8432.2542.6643.072

3.4783.8834.2864.6885.088

5.4865.8836.2796.6727.064

7.4517.8388.2248.6109.996

9.0749.4609.84610.23210.618

11.00511.39111.77712.16312.549

12.93513.32213.70814.09414.480

14.86715.25615.64616.03516.425

16.81517.20517.59417.98418.37418.765

RESISTANCE / TEMPERATURE TABLECOPPER 10Ω AT 25°C

°C

-190-180-170-160-150

-140-130-120-110-100

-90-80-70-60-50

-40-30-20-100

010203040

5060708090

100110120130140

150160170180190

200210220230240250260

0

1.4711.8842.2952.7053.112

3.5193.9234.3264.7285.128

5.5265.9236.3186.7127.104

7.4907.8768.2638.6499.035

9.0359.4219.80710.19410.580

10.96611.35211.73812.12412.511

12.89713.28313.66914.05514.442

14.82815.21715.60715.99616.386

16.77617.16617.55517.94518.33518.72619.116

9

67.2573.7580.27

86.8393.42100.08106.83113.69

126.45133.77141.29149.01156.93

165.08173.40181.97190.75199.73

208.92218.34227.99237.85247.93

258.25268.83279.67290.83302.29

314.11326.29338.86351.82365.18

378.91393.05407.60422.53

437.89453.6146.60

8

67.9074.4080.93

87.4894.08100.75107.51114.38

125.72133.03140.53148.23156.13

164.26172.56181.10189.87198.82

207.99217.39227.01236.85246.91

257.21267.76278.57289.70301.13

312.91325.05337.59350.51363.82

377.52391.62406.12421.02

436.33452.02468.00

7

68.5575.0681.58

88.1494.75

101.42108.19115.08

125.00132.29139.77147.46155.33

163.44171.72180.24188.98197.91

207.06216.44226.04235.86245.89

256.16266.60277.48288.57299.97

311.72323.82336.32349.20362.47

376.13390.19404.66419.51

434.78450.44466.40

6

69.2075.7182.84

88.8095.41102.09108.87115.77

124.28131.56139.02145.68154.53

162.62170.88179.37188.10197.01

206.14215.49225.07234.87244.88

255.12265.63276.39287.45298.82

310.52322.59333.78234.90361.13

374.75388.77403.19418.01

433.24448.86464.80

5

69.8576.3682.89

89.4696.07102.77109.56116.47

123.57130.82138.26145.90153.74

161.80170.05178.51187.22196.11

205.22214.54224.10233.88243.87

254.09264.57275.30286.33297.67

309.34321.37335.05346.59359.79

373.37387.34401.73416.51

431.70447.28463.20

4

70.5077.0183.55

90.1296.74103.44110.25117.17

112.85130.09137.51145.13152.94

160.98169.21177.66186.34195.21

204.30213.60223.14232.89242.86

253.05263.51274.22285.21296.52

308.15320.15332.52345.30358.45

372.00385.93400.28415.01

430.16445.70461.60

3

71.1577.6684.20

90.7897.41104.11110.93117.88

122.13129.36136.76144.36152.15

160.17168.38176.80185.46193.42

203.38212.66222.17231.90241.86

242.02262.45273.14284.09295.38

306.97318.94331.27344.00357.12

370.62384.52398.82413.52

428.62444.13460.00

2

71.8078.3184.86

91.4498.07104.79111.62118.58

121.42128.63136.01143.59151.36

159.36167.56175.95184.59194.32

202.46211.72221.21230.92240.85

251.00261.40272.06282.98294.24

305.80317.72330.02342.71355.79

369.26385.11379.38412.03

427.09442.57458.40

1

72.4578.9785.51

92.1098.74105.47112.31119.29

120.71127.90135.26142.82150.58

158.55166.73175.10183.71192.53

201.55210.78220.25229.94239.85

249.97260.35270.98281.87293.10

304.62316.52328.77314.42354.46

376.89381.70395.93410.55

425.57441.00456.80

RESISTANCE / TEMPERATURE TABLENICKEL 120Ω AT 0°C

°C

-70-60-50

-40-30-20-100

010203040

5060708090

100110120130140

150160170180190

200210220230240

250260270280

290300310320

0

73.1079.6286.17

92.7699.41106.15113.00120.00

120.00127.17134.52142.06149.79

157.74165.90174.25182.84191.64

200.64209.85219.29228.96238.85

248.95259.30269.91280.77291.96

303.46315.31327.53340.14353.14

366.53380.31394.49409.07

424.05439.44455.20471.20

TEMPERATURE CONVERSION TABLERead known temperature in bold face type.Corresponding temperature in degreesFahrenheit will be found in column to the rightCorresponding temperature in degreesCentigrade will be found in column to the left.

C. ____ _____F. C. _____ _____ F.0.56_____ 1 _____1.8 3.33 _____ 6 _____10.8 1.11_____ 2 _____3.6 3.89_____ 7 _____12.6 1.67_____ 3 _____5.4 4.44_____ 8 _____14.4 2.22_____ 4 _____7.2 5.00_____ 9 _____16.22.78_____ 5 _____9.0 5.56_____ 10_____18.0

FREEZING TEMPERATURE OF METALS

32°F

6000°F

5000°F

4000°F

3000°F

2000°F

1000°F

4500°F

3500°F

1500°F

500°F

TUNGSTEN ......................

RHENIUM .......................

TANTALUM .....................OSMIUM .........................

MOLYBDENUM ................

IRIDIUM .........................

NIOBIUM ........................ (COLUMBIUM)

CHROMIUM ......................

TITANIUM ........................

VANADIUM ......................

PALLADIUM ....................

COBALT .........................NICKEL ..........................

BERYLLIUM ....................

MAGANESE ....................

URANIUM .......................1084.620°C FREEZE Pt. COPPER* ........................

961.780°C FREEZE Pt SILVER* ..........................

BRASSES .......................

MAGNESIUM ...................

SILVER SOLDERS ............

BISMUTH .........................

-38.83440°C TRIPLE Pt. MERCURY* ................

................ COMMON SOLDERS

..................... LEAD & CADIUM

.................. ALUMINUM* 660.3230°C FREEZE Pt.

.............. GOLD (24 KARAT) 1064.180°C FREEZE Pt18 KARAT

12 KARAT GOLD ALLOYS

10 KARAT

.................................... IRON

.............................. RHODIUM

............................. PLATINUM

............................ ZIRCONIUM

>STAINLESS STEELS...............

...............

>CAST IRONS

...............

...............

............ TRIPLE Pt. WATER* 0.1°C

29.76460°C FREEZE Pt. GALLIUM* ................

-189.2442°C TRIPLE Pt. ARGON* ..............-218.7916°C TRIPLE Pt. OXYGEN* .............

-248.5939°C TRIPLE Pt. NEON* ..................-259.3467°C TRIPLE Pt. HELIUM* ...............

-273.1500°C ABSOLUTE ZERO* ................

* Represents information from ITS-90 Temperaure Scale.

156.5985°C FREEZE Pt. INDIUM* ................

231.9280°C FREEZE Pt. TIN* ................

419.5270°C FREEZE Pt. ZINC* ................

2500°F

THE INTERNATIONAL SYSTEM OF UNITS (SI)The information provided below is for convenient reference in providing product specification is SI.

SI Base UnitsSI is founded on seven base units:

Quantity Name of Unit Symbollength meter mmass kilogram kgtime second selectric current ampere Athermodynamic temperature centigrade or fahrenheit C or Famount of substance mole moleluminous intensity candela cd

There are also two supplementary units:

Quantity Name of Unit Symbol_____ ___ plane angle radian radsolid angle steradian sr

SI Derived UnitsDerived units are formed with base and/or supplementary units.

Quantity Name Symbol Equivalent to __force newton N kg•m/s2

pressure pascal Pa N/m2

work, energy, quantity of heat joule J N•mpower, heat flow rate watt W J/squantity of electricity coulomb C A•selectrical potential volt V V/Aelectric resistance ohm Ω V/Aelectric capacitance farad F C/Velectric conductance siemens S A/Vmagnetic flux weber Wb V•sinductance henry H Wb/Amagnetic flux density tesla T Wb/m2

frequency hertz Hz 1/sluminous flux lumen Im cd•srilluminance lux lx Im/m2

activity becquerel Bq 1/sabsorbed dose gray Gy J/kg

Common Prefixes

Prefix Symbol Means Multiple by Or by mega M 1,000,00 106

kilo k 1,000 103

hecto* h 100 102

deka* da 10 10deci* d 0.1 10-1centi* c 0.01 10-2milli m 0.001 10-3micro u 0.000,0001 10-6

*should be avoided when possible

Cat

alog

Num

ber

GG

210J

GG

202J

KK

201J

NN

201J

TF20

1JTX

201J

GG

241J

KK

241J

PP

241J

TF24

1JG

G26

1JG

G28

1JG

G30

1J

GG

201K

GG

202K

KK

201K

RR

201K

TF20

1KTX

201K

GG

241K

PP

241K

GG

261K

GG

281K

GG

301K

GG

201T

TF20

1TTX

201T

GG

241T

NN

241T

PP

241T

TF24

1TG

G28

1TG

G30

1T

GG

201E

GG

241E

Gau

geSi

ze 20 20 20 20 20 20 24 24 24 24 26 28 30 20 20 20 20 20 20 24 24 26 28 30 20 20 20 24 24 24 24 28 30 20 24

AN

SI:

TYPE

, J -

Iron

/ Con

stan

tan

*ohm

s pe

r dou

ble

foot

at 2

0°C

(68°

F).

Con

duct

ors

Sol

idS

trand

edS

olid

Sol

idS

olid

Sol

idS

olid

Sol

idS

olid

Sol

idS

olid

Sol

idS

olid

Sol

idS

trand

edS

olid

Sol

idS

olid

Sol

idS

olid

Sol

idS

olid

Sol

idS

olid

Sol

idS

olid

Sol

idS

olid

Sol

idS

olid

Sol

idS

olid

Sol

id

Sol

idS

olid

*Ohm

s.3

57.3

17.3

57.3

57.3

57.3

57.8

77.8

77.8

77.8

771.

394

2.21

63.

520

.590

.538

.590

.590

.590

.590

1.49

01.

490

2.37

03.

770

5.98

0

.298

.298

.298

.753

.753

.753

.753

1.90

53.

025

.704

1.78

0AN

SI:

TYPE

, K -

Chr

omel

/ A

lum

el

AN

SI:

TYPE

, T -

Cop

per

/ Con

stan

tan

AN

SI:

TYPE

, E -

Chr

omel

/ C

onst

anta

n

Prim

ary

Insu

latio

nG

lass

Bra

idD

oubl

e G

lass

Bra

idFu

sed

Kap

ton

Tape

Nyl

on(T

FE) t

ape,

Tef

lon

Ext

rude

d (F

EP

) Tef

lon

Gla

ss B

raid

Fuse

d K

apto

n Ta

peP

olyv

inyl

Chl

orid

e(T

FE) t

ape,

Tef

lon

Gla

ss W

rap

Gla

ss W

rap

Gla

ss W

rap

(Bra

id a

vail.

)

Gla

ss B

raid

Dou

ble

Gla

ss B

raid

Fuse

d K

apto

n Ta

peVi

treou

s S

ilica

Bra

id(T

FE) t

ape,

Tef

lon

Teflo

n E

xtru

ded

(FE

P)

Gla

ss B

raid

(Wra

p av

ail.)

Pol

yvin

yl-R

ip C

ord

Con

st.

Gla

ss W

rap

Gla

ss B

raid

(Wra

p av

ail.)

Gla

ss W

rap

Gla

ss B

raid

(Wra

p av

ail.)

(TFE

) tap

e, T

eflo

nE

xtru

ded

Teflo

n (F

EP

)G

lass

Bra

id (W

rap

avai

l.)N

ylon

Poly

viny

l Rip

Cor

d C

onst

.(T

FE) t

ape,

Tef

lon

Gla

ss B

raid

(Wra

p av

ail.)

Gla

ss W

rap

Gla

ss B

raid

Gla

ss B

raid

Out

er J

acke

tG

lass

Bra

idG

lass

Bra

idN

one,

Tw

iste

dN

ylon

(TFE

) tap

e, T

eflo

nE

xtru

ded

(FE

P) T

eflo

nG

lass

Bra

idN

one,

Tw

iste

dN

one,

Rip

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d(T

FE) t

ape,

Tef

lon

Gla

ss B

raid

Gla

ss B

raid

Gla

ss B

raid

Gla

ss B

raid

Gla

ss B

raid

Non

e, T

wis

ted

Vitre

ous

Sili

ca B

raid

(TFE

) tap

e, T

eflo

nTe

flon

Ext

rude

dG

lass

Bra

idN

one

Gla

ss B

raid

Gla

ss B

raid

Gla

ss B

raid

Gla

ss B

raid

(TFE

) tap

e, T

eflo

nE

xtru

ded

Teflo

nG

lass

Bra

idN

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Non

e(T

FE) t

ape,

Tef

lon

Gla

ss B

raid

Gla

ss B

raid

Gla

ss B

raid

Gla

ss B

raid

Min

.-Max

. O.D

..0

59 x

.105

”.0

75 x

.137

”.0

87”

.068

x .1

20”

.065

x .1

10”

.072

x .1

24”

.047

x .0

81”

.063

”.0

48 x

.096

”.0

47 x

.078

”.0

40 x

.065

”.0

37 x

.059

”.0

33 x

.053

”

.059

x .1

05”

.075

x .1

37”

.087

”.1

02 x

.174

”.0

65 x

.110

”.0

72 x

.124

”.0

47 x

.081

”.0

48 x

.096

”.0

40 x

.065

”.0

39 x

.064

”.0

33 x

.053

”

.059

x .1

05”

.065

x .1

10”

.072

x .1

24”

.047

x .0

81”

.060

x .0

95”

.048

x .0

96”

.047

x .0

78”

.039

x .0

64”

.033

x .0

53”

.059

x .1

05”

.047

x .0

81”

Est.

Shpg

.W

t. pe

r M 8 lb

s.9l

bs.

10 lb

s.11

lbs.

10 lb

s.1 1

lbs.

4 lb

s.5

lbs.

4 lb

s.5

lbs.

3 lb

s.3

lbs.

3 lb

s.

8 lb

s.9

lbs.

10 lb

s.16

lbs.

10 lb

s.11

lbs.

4 lb

s.4

lbs.

3 lb

s.3

lbs.

2 lb

s.

5 lb

s10

lbs.

11 lb

s.4

lbs.

6 lb

s.3

lbs.

5 lb

s.3

lbs.

2 lb

s.

8 lb

s.4

lbs.

Cat

alog

Num

ber

PP

161J

XPA

161J

X

PA20

1JX

PP

201J

XP

P20

2JX

PX

201J

X

PA16

1KX

PP

161K

XPA

201K

X

PP

201K

XP

P20

2KX

PP

141T

XPA

161T

X

PP

161T

XPA

201T

XP

P20

1TX

PA16

1EX

PP

201E

X

PP

161S

XG

G20

1SX

PP

201S

X

Gau

geSi

ze 16 16 20 20 20 20 16 16 20 20 20 14 16 16 20 20 16 20 16 20 20

AN

SI:

TYPE

, J -

Iron

/ Con

stan

tan

*ohm

s pe

r dou

ble

foot

at 2

0°C

(68°

F).

Con

duct

ors

Sol

idS

olid

Sol

id

Sol

idS

trand

edS

olid

Sol

id

Sol

idS

olid

Sol

idS

trand

ed

Sol

idS

olid

Sol

idS

olid

Sol

id

Sol

id

Sol

id

Sol

idS

olid

Sol

id

AN

SI:

TYPE

, K -

Chr

omel

/ A

lum

el

AN

SI:

TYPE

, T -

Cop

per

/ Con

stan

tan

AN

SI:

TYPE

, E -

Chr

omel

/ C

onst

anta

n

Prim

ary

Insu

latio

nP

olyv

inyl

Chl

orid

eP

VC

/Alu

m. M

ylar

Shi

eld

(Tw

iste

d)P

VC

/Alu

m. M

ylar

Shi

eld

(Tw

iste

d)P

olyv

inyl

Chl

orid

eP

olyv

inyl

Chl

orid

e(F

EP

) Ext

rude

d Te

flon

Min

.-Max

. O.D

..1

11 x

.188

”.2

22”

.184

”

.095

x .1

58”

.115

x .1

90”

.072

x .1

24”

.222

”

.116

x .1

88”

.184

”

.195

x .1

58”

.115

x .1

90”

.130

x .2

26”

.222

”

.111

x .1

88”

.184

”.0

95 x

.158

”

.116

x .2

50”

.059

x .1

05”

.095

x .1

58

*Ohm

s.1

37.1

37

.357

.357

.317

.357

.233

.233

.590

.590

.538

.074

.118

.118

.298

.298

.278

.704

.016

.040

.040

PV

C/A

lum

. Myl

ar S

hiel

d(T

wis

ted)

Pol

yvin

yl C

hlor

ide

PV

C/A

lum

. Myl

ar S

hiel

d(T

wis

ted)

Pol

yvin

yl C

hlor

ide

Pol

yvin

yl C

hlor

ide

AN

SI:

TYPE

, S a

nd R

- Pl

atin

um /

Rho

dium

Pol

yvin

yl C

hlor

ide

PV

C/A

lum

. Myl

ar S

hiel

d(T

wis

ted)

Pol

yvin

yl C

hlor

ide

PV

C/A

lum

. Myl

ar S

hiel

dP

olyv

inyl

Chl

orid

e

PV

C/A

lum

. Myl

ar S

hiel

d(T

wis

ted)

Pol

yvin

yl C

hlor

ide

Pol

yvin

yl C

hlor

ide

Gla

ss B

raid

Pol

yvin

yl C

hlor

ide

Out

er J

acke

tP

olyv

inyl

Chl

orid

eP

VC

PV

C

Pol

yvin

yl C

hlor

ide

Pol

yvin

yl C

hlor

ide

Ext

rude

d Te

flon

PV

C

Pol

yvin

yl C

hlor

ide

PV

C

Pol

yvin

yl C

hlor

ide

Pol

yvin

yl C

hlor

ide

Pol

yvin

yl C

hlor

ide

PV

C

Pol

yvin

yl C

hlor

ide

PV

CP

olyv

inyl

Chl

orid

e

PV

C

Pol

yvin

yl C

hlor

ide

Pol

yvim

yl C

hlor

ide

Gla

ss B

raid

Pol

yvin

yl C

hlor

ide

.222

”

.095

x .1

58”

Est.

Shpg

.W

t. pe

r M27

lbs.

28 lb

s.

20 lb

s.

14 lb

s.14

lbs.

11 lb

s.

28 lb

s.

27 lb

s.20

lbs.

14 lb

s.14

lbs.

37 lb

s.20

lbs.

28 lb

s.20

lbs.

15 lb

s.

20 lb

s.

15 lb

s.

27 lb

s.8

lbs.

14 lb

s.

.281

.266

.250

.234

.219

.203

.188

.172

.156

.141

.125

.109

.0938

.0781

.0703

.0625

.0563

.0500

.0438

.0375

.0344

.031

.0281

.0250

.0219

.0188

.0172

.0156

.0141

.0125

.0109

.0102

.0094

.0086

.0078

.0066

.0070

.0063----

7.3486.5445.8275.1894.6214.1153.6653.2642.9062.5882.3042.0531.8291.6281.4501.2911.1501.0240.91160.81180.72300.64380.57330.51060.45470.40490.36060.32110.28590.25460.22680.20190.1780.1520.1380.1270.11310.10070.089690.07987

COMPARISON OF WIRE GAUGES

Standard Wire Gauges in Approximate Decimals of an Inch and mm.

American orBrown and Sharp

Wire GaugeUS

StandardBritish

Standard orImperial

DiameterMillimeters

DiameterInches

12345678910111213141516171819202122232425262728293031323334353637383940

0.28930.25760.22940.20430.18190.16200.14430.12850.11440.10190.09070.08080.07200.06410.05710.05080.04530.04030.03590.03200.02850.02530.02260.02010.01790.01590.01420.01260.01130.01000.00890.00800.007080.006300.005610.005000.004450.003970.003530.00314

.300

.276

.252

.232

.212

.192

.176

.160

.144

.128

.116

.104

.092

.080

.072

.064

.056

.048

.040

.036

.032

.028

.024

.022

.020

.018

.0164

.0148

.0136

.0124

.0116

.0108

.010

.0092

.0084

.0076

.0068

.006

.0052

.0048

0.0090.0150.0220.0350.0550.0330.1380.2200.5600.8902.263.605.709.10

15.323.056.9

227945

0.0080.0120.0200.0310.0490.0780.1260.2000.5600.8032.033.225.108.16

12.920.651.1

204850

0.0090.0150.0230.0370.0580.0920.1480.2350.5940.9452.383.86.049.6

15.324.460.2

2401000

0.0070.0110.0180.0290.0470.0730.1190.1900.4780.7601.913.044.827.64

11.9519.376.5

191740

0.0070.0110.0180.0280.0450.0710.1160.1850.4640.7401.851.964.667.40

11.618.674.0

185740

0.0270.0440.0690.1090.1750.2760.4480.7071.782.8367.169

11.3118.0928.7645.4173.57

179.2716.9

2876

0.0120.0190.0290.0460.0740.1170.1900.2980.75261.2043.0434.7587.66

12.1719.9931.6476.09

304.31217

0.0140.0220.0340.0540.0870.1370.2220.3570.8781.4053.5515.5998.946

14.2023.3537.0188.78

355.11420

0.1620.1280.1020.0810.0640.0510.0400.0320.02010.01590.01000.00800.00630.00500.00390.003150.00200.00100.00049

0.1620.1280.1020.0810.0640.0510.0400.0320.02010.01590.01000.00800.00630.00500.00390.003150.00200.00100.00049

68

1012141618202426303234363840445056

TYPE D*W3% Re / W25% Re

TYPE G*W /

W26% Re

TYPE C*W5% Re / W26% Re

TYPE RPt /

Pt 13% Rh

TYPE SPt /

Pt 10% Rh

TYPE EChromel /

Constantan

TYPE TCopper /

Constantan

TYPE JIron /

Constantan

.009

.054

.263

.380

.158

.005

.031

.165

.222

.094

.004

.021

.104

.150

.063

.003

.015

.073

.105

.004

CopperIronConstantanChromelAlumel

RES.C A L I B R AT I O N

207/28

1119

1719/30

1911

.6593.83

18.727.0411.26

--

4.15--

7.457.80

--

.103

.5982.944.031.76.275

.633--

1.191.25

--

209702374021110214302175020955

587610628642715

329637413318336834193295

93.997.6100.5102.8114.3

207623562090212121532075

65.267.869.871.479.1

.065

.3761.852.701.11

.175

----------

816926821834846815

23.524.425.225.728.6

.026

.149

.7251.05.438.070

.166--.298.312--

322365324329334322

9.179.549.8210.011.2

.010

.059

.291

.415

.113

.027

.066--

.119

.124--

127145128130132125

3.713.853.974.064.51

.004

.003

.114

.165

.069

.010

.025--

.044

.049--

809181828380

2.222.312.372.432.70

.003

.015

.072

.104

.043

.007

.016--

.028

.031--

202220202020

.56

.58

.60

.61

.68

CopperIronConstantanChromelAlumel#11 Alloy

PlatinumPlat. - 6%Plat. - 10%Plat. - 13%Plat. - 30%

FT.RES.FT.RES.FT.RES.FT.RES.FT.RES.FT.RES.FT.RES..0006.004.018.026.011.002

.004--

.007

.008--

FT.RES.C O N D U C TO R

.004.010.012.020.032.051.064.128B & SDIAMETER

14 16 20 24 28 30 388GAUGE

THERMOCOUPLE WIRE SIZES, RESISTANCES, AND WEIGHTS

NOMINAL RESISTANCE AND WEIGHTSBARE THERMOCOUPLE WIRE AND EXTENSION WIRECONDUCTORS BASED ON OHMS PER FOOT AT 70°F

NOTE: All footages stated are in pound units except platinum calibrations which are in troy ounce units

GAUGECONSTRUCTION

CIRCULARMILS

1416/26*

4006

167/24

2828

RES. RES. RES.

THERMOCOUPLE WIRE SIZE AND RESISTANCE TABLERESISTANCE IN OHMS PER DOUBLE FOOT AT 68°F.

AWGNO.

DIAMETER(inches)

TYPE KChromel /

Alumel

324820

3294

324821

3316

324821

3316

EN

TN

Copper

Constantan

Negative (-)

Negative (-)

202430

202430

202430

Constantan

TP Positive (+)

EP Chromel 328833

3364

Positive (+) 202430

Positive (+)

2183

331838

21303370

2183

331838

20893316

AlumelKN Negative (-) 81420242830

81420242830

ChromelKP

20.280.9

324.0821.0

2089.03316.0

81420242830

Negative (-)Constantan

BASE METAL THERMOCOUPLE WIRE FT. / LB.

JN

22.891.2

365.0925.0

2353.03767.0

Positive (+)IronJP 81420242830

ANSI CODE WIRE TYPE ELEMENT POLARITY AWG WIRE FT. / LB

304.3

308.7

304.3

308.7

304.3

Positive (+)

Negative (-)

Negative (-)

Positive (+)

Negative (-)Tungsten 26% Rhenium

Tungsten 3% Rhenium

Tungsten 25% Rhenium

Tungsten 5% Rhenium

Tungsten 26% Rhenium

310.0Positive (+)

*WRN

*W3P

*W3N

*W5P

*W5N

Tungsten*WRP 24

24

24

24

24

24

45.2114.8394.0695.8

52.7134.0343.1812.3

43.3110.0281.6432.0666.6

47.4120.4308.3468.0729.8

43.3110.0281.6432.0666.6

BN

BP

RN

RP

Negative (-)

Negative (-)

Negative (-)

Positive (+)

Positive (+)

Pt-6% Rh

Pt-30% Rh

Pt

Pt-13% Rh

PtSN

46.4118.0302.2480.0715.2

Positive (+)Pt-10% RhSP 1620242628

HIGH TEMPERATURE THERMOCOUPLE WIRE

ANSI CODE CODE TYPE ELEMENT POLARITY AWG WIRE IN / T. OZ

162024262816202426281620242628

16202428

16202428

Pt = PlatinumRh = Rhodium

*Available in matched pairs only

HAZARDOUS LOCATIONS AS CLASSIFIED IN NORTH A M E R I C AHazardous (Classified) Locations In Accordance with Article 500, National Electrical Code - 1990

Class IFlammable Gases or Vapors

Division 1

• Exists under normal conditions• May exist because of

- repair operations- maintenance operations- leakage

• Released concentration because of- breakdown of equipment- breakdown of process- faulty operation of equipment- faulty operation of process

which causes simultaneous failure or electrical equipment

Division 2

• Liquids and gases are in closed con-tainers or the systems are:

- handled- processed- used

• Concentrations are normally preventedby positive mechanical ventilation.

• Adjacent to Class I, Division 1 location

Group A: Atmospheres containing Acetylene

Group B: Atmospheres such as Butadiene, Ethylene Oxide, Propylene Oxide,Acrolein, or Hydrogen (or gases or vapors equivalent in hazard to hydrogen such as manufactured gas.)

Group C: Atmospheres such as Cyclopropane, Ethyl Ether, Ethylene, or gases or vapors equivalent in hazard.

Group D: Atmospheres such as Acetone, Alcohol, Ammonia, Benzine, Benzol, Butane, Gasoline, Hexane, Lacquer Solvent vapors,

Naphtha, Natural Gas, Propane or gases or vapors equivalent in hazard.

HAZARDOUS LOCATIONS AS CLASSIFIED IN NORTH A M E R I C A

Class 2Combustible Dusts

Division 1

• Exists under normal conditions• Combustible mixture produced by:

• mechanical failure of equip-ment or machinery

• abnormal operation of equipment and provide source of ig-nition from:

• simultaneous failure of electri-cal equipment

• simultaneous failure of operation of protection devices

• other caused• Electrically conductive dusts may be

present

Division 2

• Not normally in the air• Accumulations normally sufficient to

interfere with normal operation of elec-trical equipment or other apparatus

• In the air as a result of infrequent mal-functioning of:

- handling equipment- process equipment

•Accumulations are sufficient to interferewith the safe dissipation of heat fromelectrical equipment

• Accumulations may be ignited be ab-normal conditions or failure of electri-cal equipment

Group E: Atmospheres containing combustible metal dusts (regardless of resistivity), dusts of similarly hazardous characteristics (<100kΩ/cm) or electrically conductive dusts

Group F: Atmospheres containing combustible Carbon Black, Charcoal or Coke Dusts which have > 8% total volatile material or if these dustsare sensitized so that they present an explosion hazard and hav-ing a resistivity > 100 KΩ/cm but < 100 MΩ/cm

Group G: Atmospheres containing combustible dusts having a resistivity > 100 KΩ/cm or electrically nonconductive dusts

Class 3Ignitable Fibers or Flyings

Division 1

• Fibers or materials producing com-bustible flyings are manufactured, stored of handled

Division 2

• Fibers are handled except during theprocess of manufacture or are

storedexcept during the process of man-ufacture

Not Grouped

• Manufacturers such as textilemills,

cotton related mills or clothing plants• Fibers and flyings include Rayon,

Cotton, Sisal, Hemp, Jute and Span-ish Moss