FLUKE 5628 User Guide

Hart Scientific

5626/5628

Platinum Resistance Thermometer

User’s Guide

Rev. 6B0901

Fluke Hart Scientific • 799 E. Utah Valley Drive • American Fork, UT 84003-9775 • USA
Phone: [phone] • Telefax: +1.801.763.1010 • E-mail: [e-mail]

www.hartscientific.com

Subject to change without notice. • Copyright © 2005 • Printed in USA

Rev. 6B0901

Table of Contents

1 Before You Start . . . . . . . . . . . . . . . . . . . . . . 1

1.1 Symbols Used . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2 Safety Information . . . . . . . . . . . . . . . . . . . . . . . 2

1.2.1 Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.2.2 Cautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.3 Hart Scientific Authorized Service Centers . . . . . . . . . . . 3

2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5

2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.2 Application. . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.3 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2.4 Recalibration. . . . . . . . . . . . . . . . . . . . . . . . . . 6

3 Specifications and Warranty . . . . . . . . . . . . . . . 7

3.1 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . 7

3.2 Construction . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3.3 Electrical Circuit . . . . . . . . . . . . . . . . . . . . . . . . 8

3.4 Warranty. . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

4 Installation . . . . . . . . . . . . . . . . . . . . . . . . 9

4.1 Environmental Issues . . . . . . . . . . . . . . . . . . . . . 9

4.2 Mounting. . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

4.3 Lead Wire Identification . . . . . . . . . . . . . . . . . . . . 9

5 PRT Care and Handling Guidelines. . . . . . . . . . . . 11

5.1 PRT Care . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

5.2 PRT Handling Guidelines . . . . . . . . . . . . . . . . . . . 11

6 Operation. . . . . . . . . . . . . . . . . . . . . . . . . 13

6.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

6.2 Comparison Calibration of Other Instruments. . . . . . . . . 13

6.3 Immersion Requirements . . . . . . . . . . . . . . . . . . . 13

6.4 Thermal EMF . . . . . . . . . . . . . . . . . . . . . . . . . 14

7 Accessories. . . . . . . . . . . . . . . . . . . . . . . . 15

i

7.1 Case Options . . . . . . . . . . . . . . . . . . . . . . . . . 15

7.2 PRT Termination . . . . . . . . . . . . . . . . . . . . . . . 15

8 Troubleshooting . . . . . . . . . . . . . . . . . . . . . 17

8.1 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . 17

ii

Figures

Figure 1 Hart Model 5626 and 5628 Platinum Resistance Thermometers. . . . . . 5

Figure 2 Standard Dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Figure 3 PRT Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Figure 4 Probe Termination Examples . . . . . . . . . . . . . . . . . . . . . . . 15

iii

Tables

Table 1 International Electrical Symbols . . . . . . . . . . . . . . . . . . . . . . 1

Table 2 Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

iv

1 Before You Start

1.1 Symbols Used

Before You Start

1

Table 1 lists the International Electrical Symbols. Some or all of these sym
bols may be used on the instrument or in this manual.

Table 1 International Electrical Symbols

Symbol Description

AC (Alternating Current)

AC-DC

Battery

CE Complies with European Union Directives

DC

Double Insulated

Electric Shock

-

Fuse

PE Ground

Hot Surface (Burn Hazard)

Read the User’s Manual (Important Information)

Off

On

1

5626/5628

User’s Guide

Symbol Description

Canadian Standards Association

OVERVOLTAGE (Installation) CATEGORY II, Pollution Degree 2 per
I E C1010-1 r efers to the level of Im p ulse Withstand Voltage protect i o n
provided. Equipment of OVERVOLTAGE CATEGORY II is energy-con
suming equipment to be supplied from the fixed installation. Exam
ples include household, office, and laboratory appliances.

C-TICAustralianEMCMark

-

-

The European Waste Electrical and Electronic Equipment (WEEE) Di
rective (2002/96/EC) mark.

1.2 Safety Information

Use this instrument only as specified in this manual. Otherwise, the protec­tion provided by the instrument may be impaired.

The following definitions apply to the terms “Warning” and “Caution”.

“Warning” identifies conditions and actions that may pose hazards to the
user.

“Caution” identifies conditions and actions that may damage the instrument
being used.

1.2.1

To avoid personal injury, follow these guidelines.

Warnings

•

DO NOT use this instrument to measure the temperature of any haz
ardous live component.

•

DO NOT use this unit for any application other than calibration work.

•

DO NOT use this unit in environments other than those listed in the
user’s manual.

•

Use of this instrument at high temperatures for extended periods of
time can cause the handle to become hot.

•

Follow all safety guidelines listed in the user’s manual.

•

Calibration Equipment should only be used by Trained Personnel.

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1.2.2
Cautions

To avoid possible damage to the instrument, follow these guidelines.

•

DO NOT remove the label from the handle. This cautions the user con

-

cerning the delicate nature of the instrument.

2

Before You Start

DO NOT drop or bang the probe in any way. This will cause damage to

•

the probe internally and affect its calibration.
Read Section 5 entitled “PRT Care and Handling Guidelines” before re

•

moving the PRT from the shipping box or case. Incorrect handling can
damage the PRT and void the warranty.

Keep the shipping container in case it is necessary to ship the PRT. In

•

correct packaging of the PRT for shipment can cause irreparable dam
age.

1.3 Hart Scientific Authorized Service
Centers

Please contact one of the following authorized Service Centers to coordinate
service on your Hart product:

Hart Scientific, Inc.

799 E. Utah Valley Drive
American Fork, UT 84003-9775
USA

1

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Phone: [phone]
Telefax: +1.801.763.1010
E-mail: [e-mail]

Fluke Nederland B.V.

Customer Support Services
Science Park Eindhoven 5108
5692 EC Son
NETHERLANDS

Phone: [phone]
Telefax: [phone]
E-mail: [e-mail]

Fluke Int'l Corporation

Service Center - Instrimpex
Room 2301 Sciteck Tower
22 Jianguomenwai Dajie
Chao Yang District
Beijing 100004, PRC
CHINA

3

5626/5628

User’s Guide

Phone: [phone]
Telefax: [phone]
E-mail: [e-mail]

Fluke South East Asia Pte Ltd.

Fluke ASEAN Regional Office
Service Center
60 Alexandra Terrace #03-16
The Comtech (Lobby D)
118502
SINGAPORE

Phone: [phone]
Telefax: [phone]
E-mail: [e-mail]

When contacting these Service Centers for support, please have the follow­ing information available:

• Model Number

•

Serial Number

•

Complete description of the problem

4

2 Introduction

2.1 General

The Hart Platinum Resistance Thermometers (PRT) models 5626 and 5628,
are designed to be the best secondary standard interpolating instrument
converting temperature to resistance. The PRTs are used with a readout de
vice to detect temperature changes or actual temperature. The PRTs cover
the International Temperature Scale of 1990 (ITS-90) range from –200°C to
661°C. Two standard resistance values are available. The 5626 is 100Ω and
the 5628 is 25.5Ω. Standard lengths are 12, 15, and 20 inches. Custom
lengths are available on request.

The two PRTs are hand constructed at Hart Scientific by experts with years
of PRT manufacturing experience. Each PRT is carefully annealed at the ap
propriate temperatures and precisely tested for stability. The sensing ele
ment is fabricated using high purity platinum wire wound in a strain free
design on a specially designed support. The 1/4 inch O.D. Inconel 600
sheaths are sealed with a specially mixed gas and fit with a terminal box
handle and strain relieved connection to the four-wire cable. Gold plated
spade lugs terminate the wires.

Introduction

2

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-

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2.2 Application

Hart 5626 and 5628 thermometers are classified as secondary standards. A
secondary standard is defined in terms of transfer of the ITS-90 from a
standards laboratory to a customer’s laboratory. Secondary standards are

Figure 1 Hart Model 5626 and 5628 Platinum Resistance Thermometers

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5626/5628

User’s Guide

2.3 Calibration

2.4 Recalibration

calibrated using a primary standard that has been calibrated in a primary
calibration laboratory using known intrinsic values.

In order for any instrument to be used as a standard it must be calibrated.
The PRTs are calibrated in Hart Scientific's calibration laboratory and pro
vided with a NIST traceable “Report of Calibration”.

At the time of purchase, the 5626 and 5628 are calibrated over their entire
range (–196°C to 660°C) at specified ITS-90 fixed points. Generally, a sec
ondary PRT is calibrated by comparison method. All PRTs calibrated by Hart
Scientific are calibrated using standard calibration techniques.

-

-

The recalibration of the 5626/5628 Secondary PRT should be scheduled ac
cordingtotheuser’scompanyQualityAssurancerequirements.Normally,a
PRT is recalibrated annually. Unless the PRT is used only over a limited
range, calibration over the full range of the PRT (–196°C to 661°C) is recom­mended. For information on recalibrating your 5626 or 5628, contact Hart
Scientific’s Customer Service department for an RMA number and current
pricing (see Section , Before You Start).

Depending on the user’s Quality Assurance requirements, the PRT drift
should be checked periodically at the Triple Point of Water (TPW). Section
8,Troubleshooting, provides information on drift with respect to mechanical
shock and oxidation. If the R
calibration tolerances, a full recalibration should be scheduled.

cannot be restored after annealing to within

tp

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6

Specifications and Warranty

3 Specifications and Warranty

3.1 Specifications

See Table 2 and Figure 2.

Table 2 Specifications

5626 5628

Temperature Range –200°C to 661°C

R

tp

Resistance RatioW(Ga)

Calibration Uncertainty
(k=2)

Short-Term Stability ±0.003°C ±0.002°C

Long-Term Drift (Rtp)

Sheath Inconel™ 600

Handle Temperature
Range

Lead Wires 4-wire Super-Flex PVC, 22 AWG

Termination Gold-plated spade lugs

Size 304.8 mm x 6.35 mm dia. (12" L x 0.25")

100Ω ±1Ω at 0.01°C 25.5Ω ±0.5Ω at 0.01°C

W(302.9146K) ≥1.11807

α ≥ 0.003925

±0.006°C at –200°C

±0.004°C at 0°C
±0.009°C at 420°C
±0.014°C at 661°C

≤0.03°C with 500 hours at

≤0.02°C with 500 hours at

661°C

0°C to 80°C

381 mm x 6.35 mm dia.(15" L x 0.25”)

508 mm x 6.35 mm dia. (20" L x 0.25")

3

661°C

Strain Relief

Lead Wire

Figure 2 Standard Dimensions

65 mm

(2.5")

5626

≈2 meters

(6')

SN:0021

Terminal Box

562X-12 12"
562X-15 15"
562X-20 20”

Inconel Sheath

Gold-plated Terminals

≈152 mm

(6")

6.35 mm
(.25")

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5626/5628

User’s Guide

3.2 Construction

3.3 Electrical Circuit

3.4 Warranty

The Model 5626 and 5628 PRTs cover the range from –200°C to 661°C. The
sensor elements are crafted using high purity platinum wire wound in a
strain free design on a specially designed support.

The PRTs are provided with a terminal box handle. The two meter cable has
four Super-Flex wires enclosed in a PVC jacket with a stainless steel spring
strain relief. Gold plated spade lugs terminate the wires.

Hart Scientific, Inc. (Hart) warrants this product to be free from defects in
material and workmanship under normal use and service for a period as
stated in our current product catalog from the date of shipment. This war
ranty extends only to the original purchaser and shall not apply to any
product which, in Hart’s sole opinion, has been subject to misuse, alteration,
abuse or abnormal conditions of operation or handling.

Software is warranted to operate in accordance with its programmed in­structions on appropriate Hart products. It is not warranted to be error free.

-

Hart’s obligation under this warranty is limited to repair or replacement of a
product which is returned to Hart within the warranty period and is deter­mined, upon examination by Hart, to be defective. If Hart determines that
the defect or malfunction has been caused by misuse, alteration, abuse or
abnormal conditions or operation or handling, Hart will repair the product
and bill the purchaser for the reasonable cost of repair.

To exercise this warranty, the purchaser must forward the product after call
ing or writing an Authorized Hart Scientific Service Center (see Section 1.3
on page 3) for authorization. The Service Center assumes NO risk for
in-transit damage.

THE FOREGOING WARRANTY IS PURCHASER’S SOLE AND EXCLUSIVE REM
EDY AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTY OR MERCHANT
ABILITY, OR FITNESS FOR ANY PARTICULAR PURPOSE OR USE. HART SHALL
NOT BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL, OR CONSE
QUENTIAL DAMAGES OR LOSS WHETHER IN CONTRACT, TORT, OR
OTHERWISE.

8

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4 Installation

4.1 Environmental Issues

Ideally, temperature calibration equipment should be used in a calibration
laboratory or other facility specifically designed for this purpose. Environ
mental requirements include:

Stable temperature and relative humidity <80%

•

Clean, draft-free area

•

Low noise level: low radio frequency, magnetic or electrical interfer

•

ence
Low vibration levels

•

4.2 Mounting

Most often temperature standards, primary and secondary, are used to cali­brate other temperature-sensitive equipment. The PRT must be mounted
carefully to avoid any damage to the sheath or sensor. If the fluid bath used
does not have a lid designed for PRT insertion, clamps should be used to
ensurethehandleandcablearenotimmersed.Do not screw the clamps
too tight. Over tightening will damage the sheath. If metal comparison
blocks are used in the bath, maintain a close fit between the thermometer
sheath and the well in the comparison block. However, allow for the ther­mal expansion of the thermometer sheath when determining block well
tolerances.

Installation

4

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-

4.3 Lead Wire Identification

The 5626 and 5628 PRTs are equipped with a four-wire cable. The same
circuit schematic applies to both PRTs (see Figure 3). Four lead wires are
used to cancel lead wire resistance. For best results, the readout device
should be equipped to handle four-terminal resistors.

BLACK

(Heat Shrink)

Figure 3 PRT Schematic

The lead wires are four different colors. Lead wire pairs attached to each
end of the sensor are identified by red and black heat shrink tubing.

RED

(Heat Shrink)

9

PRT Care and Handling Guidelines

5 PRT Care and Handling

Guidelines

5.1 PRT Care

CAUTION: READ THIS SECTION BEFORE REMOVING THE PRT

FROM THE S HIPPING BOX OR CASE

The 5626 and 5628 Platinum Resistance Thermometers (PRTs) are delicate
instruments. Care must be taken in handling the PRTs to maintain calibra
tion accuracy. The stress free design of the PRT sensor reduces the effects of
mechanical shock. In addition, contamination problems of the sensor at high
temperature have been eliminated. However, care should still be used when
handling the PRT even though the Inconel sheath is durable and provides
good protection for the sensor. Correct handling of the PRT will prolong the
life expectancy. When not in use, the PRT should be stored in the protective
case provided by Hart.

Note: The PRT sheath changes color after use at high temperatures.

The PRT may arrive with a brown tint to the sheath due to calibration
at high temperatures.

5

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The handle is not designed to be immersed. The temperature limits of the
handle are: 0°C to 80°C. Temperatures outside these limits can damage the
sealed portion of the handle and the connectors.

5.2 PRT Handling Guidelines

•

DO anneal the thermometer after shipment. Shipping the thermometer
can cause mechanical shocks that effect the accuracy of the thermome
ter. Therefore, if possible, we advise that the thermometer be annealed
before use. The thermometer should be annealed at 500°C overnight
or 660°C for four (4) hours.

•

DO keep the thermometer as clean as possible. Always remove any
fluid from the sheath immediately after taking the thermometer from a
bath.

•

DO immerse the thermometer in the appropriate liquid for the temper
ature range. If a dry block is used, the well diameter should allow the
PRT to comfortably slip in and out without excess movement. For best
results, immerse the thermometer as deep as possible to avoid “stem
effect” (the temperature error caused by the conduction of heat away
from the sensor). Do not submerge the handles.

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11

5626/5628

User’s Guide

DO allow sufficient time for the thermometer to stabilize before making

•

measurements. This allows for the best accuracy.
DO use the correct drive current with the thermometer to prevent error

•

in temperature or resistance. Hart Scientific recommends 1mA.
DO anneal the thermometer at 600 to 661°C for 12 hours if it becomes

•

oxidized.
DO use the protective shipping box or case provided or other protec

•

tion when the thermometer is not in use.
DO NOT subject the thermometer to any physical shock or vibration.

•

DO NOT use pliers or other devices to squeeze the sheath. This action

•

can permanently damage the PRT.
DO NOT subject the thermometer to temperatures above the highest

•

specified operating temperature.
DO NOT expose the thermometer’s handle or cables to extreme tem

•

peratures. The temperature limits of the handle are: 0°C to 80°C
DO NOT submerge the handle or cable in liquids.

•

DO NOT screw a clamp down so tight that it dents the sheath. This can

•

permanently damage the PRT.

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12

6 Operation

6.1 General

For best results, be familiar with the operation of the heat source and the
read-outinstrument.Besuretofollowthe manufacturer’s instructions for
the read-out instrument and the heat source.

6.2 Comparison Calibration of Other
Instruments

The uniformity and stability of the heat source and the degree of accuracy
required determine the number of temperature measurements necessary.
However, to follow “good” practice procedures, always measure the triple
point of water (R
equation provides the most accurate measurement of the ratio:

R

W

All PRTs experience errors caused by self-heating of the element.
Self-heating is a combination of two factors, heat dissipation and heat sink.
Self-heating error can be reduced to have a negligible effect if the PRT is
used with the same excitation current and medium in which it was
calibrated.

t

=

t

R

tp

) after each temperature measurement. The following

tp

Operation

6

6.3 Immersion Requirements

Stem effect can cause measurement errors for any thermometer not im
mersed in the fluid at least 152 mm (6 inches). This error is due to heat lost
or gained by the sensing element through the thermometer stem. In addi
tion, heat losses occur due to radiation losses from the sensing element to
the housing.

The immersion depth for standards is dependent on several factors includ
ing accuracy requirements and type of liquid. Therefore, we recommend a
152 mm (6 inches) minimum immersion depth. However, remember the
handle limitations. The handle is not designed to be immersed. The temper
ature limits of the handle are 0°C to 80°C. Temperatures outside these limits
can damage the handle. Convection of heat from the heat source must be
kept within the handle limits.

The exact immersion depth required can be determined by performing a
gradient test taking measurements approximately every 1.27 cm (.5 inches)
until there is a significant difference in readings. Allow the thermometer to
stabilize at each new depth. Plot the results to see the stem effect.

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5626/5628

User’s Guide

6.4 Thermal EMF

Two factors contribute to thermal EMF, chemical consistency and physical
consistency. Variations in chemical structure due to impurities can contrib

­ute to thermal EMF. Also discrepancies in crystal structure can contribute to
thermal EMF. These factors are minimized by annealing the full length of
wire before construction of the PRT.

Likewise, connection to extension lead wires and readout instruments can
beasourceofthermalEMF.ThethermalEMFiscausedbyadifferencein
temperature between two connections. If the two connections are the same
temperature, there will be little or no thermal EMF effects. However, if there
is a substantial temperature difference between connections, the thermal
EMF effects will be significant. Therefore, cover or insulate any exposed
bridge or galvanometer terminals to lessen the source of error. The effects of
thermal EMF can be canceled by using an AC bridge or a DC bridge with re
versible current.

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14

7 Accessories

7.1 Case Options

The 5626/5628 PRT comes in a rigid case appropriate for the length of the
probe.

Model Number 2601 PRT Protective Case for 5626-12 and 5628-12

•

PRT
Model Number 2609 PRT Protective Case for 5626-15, 5628-15,

•

5626-20, and 5628-20 PRT

7.2 PRT Termination

The 5626/5628 PRT can be terminated in three ways (Figure 4) depending
on the user’s requirements:

Gold Plated Spade Lug

•

Bare Wire

•

5-Pin Din Connector

•

Accessories

7

Spade Lug

(standard)

Bare Wire

(customer option)

5-Pin DIN

(customer option)

Figure 4 Probe Termination Examples

5

1

2

4

3

15

8 Troubleshooting

8.1 Troubleshooting

In the event that the probe appears to function abnormally, this section may
be of use in solving the problem. Several possible problem conditions are
described along with likely causes and solutions. If a problem arises, please
read this section carefully and attempt to understand and solve the problem.
If the probe seems faulty or the problem cannot otherwise be solved, con
tact an Authorized Hart Scientific Service Center (see Section 1.3) for assis
tance. Be sure to have the model number and serial number of your probe
available.

Problem Causes and Solutions

Data changes greater than

0.1°C are observed

Data changes less than

0.1°C

Data unstable

Mechanical shock can cause temperature errors as great

•

as 0.5°C. If this is observed, first measure and record the
R

Next anneal the PRT at 660°C overnight. Measure the

tp.

R

again. The annealing should decrease the Rtp. If the

tp

R

is stable, recalibrate the PRT.

tp

Slight mechanical shock can cause temperature errors

•

less than 0.1°C. If this is observed, first measure and re­cord the R
Measure the R
the R
several times. When the R
If the R
Scientific Service Center (see Section 1.3).

•

Oxidation of the platinum sensor may occur after pro­longed use between 200 – 450°C. This oxidation will
demonstrate itself by an increase in R

0.1°C. To reduce the effects of oxidation, anneal the PRT
at 600 – 661°C overnight (12 hr.). Measure the R
Repeat the annealing, R
times This annealing process should return R
calibration tolerances. If the R
erance, the PRT is usable. If the R
tion tolerance, but it is stable, recalibrate the PRT.

•

If the data is unstable at the Triple Point of Water (TPW),
check the connector. If the connector is correct, contact
an Authorized Hart Scientific Service Center (see Section

1.3). The PRT may be damaged and need repair.

•

If the data is unstable at high temperatures, it may be
due to electrical noise in the system. Reduce the temper
ature and observe the data. If it is stable, electrical noise
is interfering with the measurements at high tempera
tures. Check the grounding of the readout device and
the heat source. A faulty ground on either device could
interfere with high temperature measurements. A
ground wire attached to the metal sheath of the PRT
may help to reduce electrical noise interference.

Troubleshooting

Next anneal the PRT at 660°C overnight.

tp.

again. The annealing should decrease

tp

. Repeat the annealing, Rtpmeasurement cycle

tp

does not stabilize, contact an Authorized Hart

tp

is stable, recalibrate the PRT.

tp

of less than

tp

measurement cycle several

tp

is within calibration tol

tp

is not within calibra

tp

to within

tp

again.

tp

8

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17

5626/5628

User’s Guide

Problem Causes and Solutions

Temperature readout differ
ent than expected, e.g. the
heat source is set at 300°C,
the PRT measures 275°C.

-

Measure the PRT resistance at TPW.

•

If the resistance of the PRT is less than the rated resis

•

tance, e.g. 70 Ω for the 5626, there may be a short in
the sensor. Contact an Authorized Hart Scientific Service
Center (see Section 1.3).

If the resistance of the PRT is only a few ohms, there

•

may be a short in the four lead-wires. Contact an Autho
rized Hart Scientific Service Center (see Section 1.3).

If the PRT is open, the resistance will be “Out of Limits”

•

or in the kilo-ohm or mega-ohm range. Contact an Au
thorized Hart Scientific Service Center (see Section 1.3).

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18