5626/5628
Platinum Resistance Thermometer
March 2014
© 2014 Fluke Corporation. All rights reserved. Specifications are subject to change without notice.
All product names are trademarks of their respective companies.
User's Guide
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LIMITED WARRANTY AND LIMITATION OF LIABILITY
Each Fluke product is warranted to be free from defects in material and workmanship under normal use and
service. The warranty period is one year and begins on the date of shipment. Parts, product repairs, and
services are warranted for 90 days. This warranty extends only to the original buyer or end-user customer of
a Fluke authorized reseller, and does not apply to fuses, disposable batteries, or to any product which, in
Fluke's opinion, has been misused, altered, neglected, contaminated, or damaged by accident or abnormal
conditions of operation or handling. Fluke warrants that software will operate substantially in accordance
with its functional specifications for 90 days and that it has been properly recorded on non-defective media.
Fluke does not warrant that software will be error free or operate without interruption.
Fluke authorized resellers shall extend this warranty on new and unused products to end-user customers
only but have no authority to extend a greater or different warranty on behalf of Fluke. Warranty support is
available only if product is purchased through a Fluke authorized sales outlet or Buyer has paid the
applicable international price. Fluke reserves the right to invoice Buyer for importation costs of
repair/replacement parts when product purchased in one country is submitted for repair in another country.
Fluke's warranty obligation is limited, at Fluke's option, to refund of the purchase price, free of charge repair,
or replacement of a defective product which is returned to a Fluke authorized service center within the
warranty period.
To obtain warranty service, contact your nearest Fluke authorized service center to obtain return
authorization information, then send the product to that service center, with a description of the difficulty,
postage and insurance prepaid (FOB Destination). Fluke assumes no risk for damage in transit. Following
warranty repair, the product will be returned to Buyer, transportation prepaid (FOB Destination). If Fluke
determines that failure was caused by neglect, misuse, contamination, alteration, accident, or abnormal
condition of operation or handling, including overvoltage failures caused by use outside the product’s
specified rating, or normal wear and tear of mechanical components, Fluke will provide an estimate of repair
costs and obtain authorization before commencing the work. Following repair, the product will be returned to
the Buyer transportation prepaid and the Buyer will be billed for the repair and return transportation charges
(FOB Shipping Point).
THIS WARRANTY IS BUYER'S SOLE AND EXCLUSIVE REMEDY AND IS IN LIEU OF ALL OTHER
WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTY
OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. FLUKE SHALL NOT BE LIABLE
FOR ANY SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL DAMAGES OR LOSSES,
INCLUDING LOSS OF DATA, ARISING FROM ANY CAUSE OR THEORY.
Since some countries or states do not allow limitation of the term of an implied warranty, or exclusion or
limitation of incidental or consequential damages, the limitations and exclusions of this warranty may not
apply to every buyer. If any provision of this Warranty is held invalid or unenforceable by a court or other
decision-maker of competent jurisdiction, such holding will not affect the validity or enforceability of any other
provision.
Fluke Corporation
P.O. Box 9090
Everett, WA 98206-9090
U.S.A.
Fluke Europe B.V.
P.O. Box 1186
5602 BD Eindhoven
The Netherlands
11/99
To register your product online, visit register.fluke.com
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Table of Contents
Chapter Title Page
1 Introduction ......................................................................................... 1-1
1.1 General ...................................................................................... 1-1
1.2 Application ................................................................................. 1-1
1.3 Calibration.................................................................................. 1-2
1.4 Recalibration .............................................................................. 1-2
2 Before You Start .................................................................................. 2-1
2.1 Symbols Used............................................................................ 2-1
2.2 Safety Information ...................................................................... 2-2
2.2.1 Warnings ................................................................................ 2-2
2.2.2 Cautions ............................................................................. 2-2
2.3 Authorized Service Centers ...................................................... 2-3
3
4
5 PRT Care and Handling Guidelines ................................................... 5-1
6
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Specifications ...................................................................................... 3-1
3.2 Construction............................................................................... 3-2
3.3 Electrical Circuit ......................................................................... 3-2
3.4 Warranty .................................................................................... 3-2
Installation ........................................................................................... 4-1
4.1 Environmental Issues ................................................................ 4-1
4.2 Mounting .................................................................................... 4-1
4.3 Lead Wire Identific
5.1 PRT Care ................................................................................... 5-1
5.2 PRT Handling Guidelines .......................................................... 5-2
Operation ............................................................................................. 6-1
6.1 General ...................................................................................... 6-1
ation ............................................................. 4-2
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6.2 Comparison Calibration of Other Instruments ........................... 6-1
6.3 Immersion Requirements........................................................... 6-1
6.4 Thermal EMF ............................................................................. 6-2
7 Accessories ......................................................................................... 7-1
7.1 Case Options ............................................................................. 7-1
7.2 PRT Termination........................................................................ 7-1
8 Troubleshooting .................................................................................. 8-1
8.1 Troubleshooting ......................................................................... 8-1
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List of Tables
Table Title Page
1. International Electrical Symbols ................................................................ 1-1
2. Specifications ............................................................................................ 3-1
iii
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List of Figures
Figure Title Page
1. The 5626 and 5628 Platinum Resistance Thermometers ......................... 2-2
2. Standard Dimensions ................................................................................ 3-2
3. PRT Schematic ......................................................................................... 4-2
4. Probe Termination Examples .................................................................... 7-1
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1.1 Symbols Used
Table 1 lists the International Electrical Symbols. Some or all of these symbols
may be used on the instrument or in this manual.
Table 1. International Electrical Symbols
Symbol Description
AC (Alternating Current)
AC-DC
Chapter 1
Before You Start
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)
O Off
I On
Canadian Standards Association
OVERVOLTAGE (Installation) CATEGORY II, Pollution
Degree 2 per IEC1010-1 refers to the level of Impulse
CATII
Withstand Voltage protection provided. Equipment of
OVERVOLTAGE CATEGORY II is energy-consuming
equipment to be supplied from the fixed installation. Examples
include household, office, and laboratory appliances.
C-TIC Australian EMC Mark
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The European Waste Electrical and Electronic Equipment
(WEEE) Directive (2002/96/EC) mark.
1-1
5626/5628
User's Guide
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 Warnings
Warning
To avoid personal injury, follow these guidelines.
• •DO NOT use this instrument to measure the temperature of
any hazardous 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.
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 concerning the delicate nature of the instrument.
• 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 removing 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. Incorrect packaging of the PRT for shipment can
cause irreparable damage.
Caution
1-2
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2.1 General
The 5626 and 5628 Platinum Resistance Thermometers (PRT) models are
designed to be the best secondary standard interpolating instrument converting
temperature to resistance. The PRTs are used with a readout device 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 100 Ω and the
5628 is 25.5 Ω. Standard lengths are 12, 15, and 20 inches. Custom lengths are
available on request.
Chapter 2
Introduction
The two PRTs are hand constructed by experts with years of PRT manufacturing
experience. Each PRT is carefully annealed at the appropriate temperatures and
precisely tested for stability. The sensing element is fabricated using high purity
platinum wire wound in a strain free design on a specially designed support. The
¼ 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.
2.2 Application
The 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
2-1
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Figure 1. The 5626 and 5628 Platinum Resistance Thermometers
calibrated using a primary standard that has been calibrated in a primary
calibration laboratory using known intrinsic values.
2.3 Calibration
In order for any instrument to be used as a standard it must be calibrated. The
PRTs are calibrated in Hart’s Scientific Calibration laboratory and provided 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 secondary
PRT is calibrated by comparison method. All PRTs calibrated by Hart Scientific
are calibrated using standard calibration techniques.
2.4 Recalibration
The recalibration of the 5626/5628 Secondary PRT should be scheduled
according to the user’s company Quality Assurance requirements. 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 Fluke’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
tolerances, a full recalibration should be scheduled
cannot be restored after annealing to within calibration
tp
2-2
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See Table 2 and Figure 2.
Chapter 3
Specifications
Table 2. Specifications
Temperature Range −200 °C to 661 °C
Rtp 100 Ω ±1 Ω at 0.01 °C 25.5 Ω ±0.5 Ω at 0.01 °C
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
≤ 0.03 °C with 500 hours at
5626 5628
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
≤ 0.02 °C with 500 hours at
661 °C
0 °C to 80 °C
661 °C
304.8 mm x 6.35 mm dia. (12" L x 0.25")
Size
381 mm x 6.35 mm dia.(15" L x 0.25”)
508 mm x 6.35 mm dia. (20" L x 0.25")
3-1
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Strain Relief
Lead Wire
Figure 2. Standard Dimensions
3.2 Construction
The 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.
3.3 Electrical Circuit
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.
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")
3-2
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4.1 Environmental Issues
Ideally, temperature calibration equipment should be used in a calibration
laboratory or other facility specifically designed for this purpose. Environmental
requirements include:
• Stable temperature and relative humidity < 80 %
• Clean, draft-free area
• Low noise level: low radio frequency, magnetic or electrical interference
• Low vibration levels
Chapter 4
Installation
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 ensure the handle and
cable are not immersed. 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.
4-1
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4.3 Lead Wire Identification
BLACK
(Heat Shrink)
Figure 3. PRT Schematic
RED
(Heat Shrink)
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.
4-2
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PRT Care and Handling Guidelines
5.1 PRT Care
Caution
Read this section before removing the PRT from the shipping
box or case.
The 5626 and 5628 Platinum Resistance Thermometers (PRTs) are delicate
instruments. Care must be taken in handling the PRTs to maintain calibration
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.
Chapter 5
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.
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.
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5.2 PRT Handling Guidelines
• DO anneal the thermometer after shipment. Shipping the thermometer can
cause mechanical shocks that affect the accuracy of the thermometer.
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 temperature
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.
• 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. Fluke 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 protection 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
temperatures. 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.
5-2
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Chapter 6
Operation
6.1 General
For best results, be familiar with the operation of the heat source and the readout instrument. Be sure to follow the 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
provides the most accurate measurement of the ratio:
) after each temperature measurement. The following equation
tp
R
t
W =
t
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.
R
tp
6.3 Immersion Requirements
Stem effect can cause measurement errors for any thermometer not immersed 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 addition, heat losses occur
due to radiation losses from the sensing element to the housing.
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The immersion depth for standards is dependent on several factors including
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 temperature 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.
6.4 Thermal EMF
Two factors contribute to thermal EMF, chemical consistency and physical
consistency. Variations in chemical structure due to impurities can contribute 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 be a
source of thermal EMF. The thermal EMF is caused by a difference in
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 reversible current.
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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
Chapter 7
Accessories
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
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Spade Lug
(standard)
Bare Wire
(customer option)
5-Pin DIN
(customer option)
5
1
2
4
3
Figure 4. Probe Termination Examples
7-2
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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, contact an Authorized
Service Center (see Section 1.3) for assistance. Be sure to have the model
number and serial number of your probe available.
Chapter 8
Troubleshooting
Problem Causes and Solutions
Data changes greater than
0.1 °C are observed
Data changes less than
0.1 °C
• 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
tp
overnight. Measure the R
annealing should decrease the R
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
. Next anneal the PRT at 660 °C
tp
overnight. Measure the R
annealing should decrease the R
Repeat the annealing, R
cycle several times. When the R
stable, recalibrate the PRT. If the R
not stabilize, contact an Authorized
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
the annealing, R
measurement cycle
tp
again. The
tp
. If the
tp
again. The
tp
.
tp
measurement
tp
is
tp
of less than
tp
again. Repeat
tp
does
tp
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Data unstable
several times this annealing process
should return R
tolerances. If the R
tolerance, the PRT is usable. If the R
not within calibration 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 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
temperature and observe the data. If it is
stable, electrical noise is interfering with
the measurements at high temperatures.
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.
to within calibration
tp
is within calibration
tp
is
tp
Temperature readout different 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 resistance, e.g. 70 Ω for the
5626, there may be a short in the sensor.
Contact an Authorized 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 Authorized Service
Center (see Section 1.3).
• If the PRT is open, the resistance will be
“Out of Limits” or in the kilo-ohm or megaohm range. Contact an Authorized Service
Center (see Section 1.3).
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