Hart Scientific
5626/5628
Platinum Resistance Thermometer
User’s Guide
Rev. 532801
Table of Contents
i
Figures
iii
1
Before You Start
1
Before You Start
1.1
Symbols Used
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
IEC1010-1 refers to the level of Impulse Withstand Voltage protection
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.
CAT
C-TIC Australian EMC Mark
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 protec-
tion 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
To avoid personal injury, follow these guidelines.
• 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.
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
1
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.
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
Phone: +1.801.763.1600
Telefax: +1.801.763.1010
E-mail: [email protected]
Fluke Nederland B.V.
Customer Support Services
Science Park Eindhoven 5108
5692 EC Son
NETHERLANDS
Phone: +31-402-675300
Telefax: +31-402-675321
E-mail: [email protected]
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: +86-10-6-512-3436
Telefax: +86-10-6-512-3437
E-mail: [email protected]
Fluke South East Asia Pte Ltd.
Fluke ASEAN Regional Office
Service Center
60 Alexandra Terrace #03-16
The Comtech (Lobby D)
118502
SINGAPORE
Phone: +65 6799-5588
Telefax: +65 6799-5588
E-mail: [email protected]
When contacting these Service Centers for support, please have the follow-
ing information available:
• Model Number
• Serial Number
• Complete description of the problem
4
2
Introduction
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.
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
5
5626/5628
User’s Guide
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 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.
2.4
Recalibration
The recalibration of the 5626/5628 Secondary PRT should be scheduled ac-
cording 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 recom-
mended. 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 Rtp cannot be restored after annealing to within
calibration tolerances, a full recalibration should be scheduled.
6
3
Specifications and Warranty
3
Specifications and Warranty
3.1
Specifications
Table 2 Specifications
5626
5628
Temperature Range
Rtp
–200°C to 661°C
100Ω 1Ω at 0.01°C
25.5Ω 0.5Ω at 0.01°C
Resistance RatioW(Ga)
W(302.9146K) ≥1.11807
α ≥ 0.003925
Calibration Uncertainty
(k=2)
0.006°C at –200°C
0.004°C at 0°C
0.009°C at 420°C
0.014°C at 661°C
Short-Term Stability
0.003°C
0.002°C
Long-Term Drift (Rtp)
≤0.03°C with 500 hours at
≤0.02°C with 500 hours at
661°C
661°C
Sheath
Inconel™ 600
Handle Temperature
Range
0°C to 80°C
Lead Wires
Termination
Size
4-wire Super-Flex PVC, 22 AWG
Gold-plated spade lugs
304.8 mm x 6.35 mm dia. (12" L x 0.25")
381 mm x 6.35 mm dia.(15" L x 0.25”)
508 mm x 6.35 mm dia. (20" L x 0.25")
562X-12 12"
562X-15 15"
562X-20 20”
65 mm
(2.5")
5626
SN:0021
6.35 mm
(.25")
Inconel Sheath
Strain Relief
Terminal Box
Lead Wire
Gold-plated Terminals
≈2 meters
(6')
≈152 mm
(6")
Figure 2 Standard Dimensions
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5626/5628
User’s Guide
3.2
3.3
3.4
Construction
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.
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.
Warranty
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 in-
structions 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 deter-
mined, 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-
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
4
Installation
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 cali-
brate 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 ther-
mal expansion of the thermometer sheath when determining block well
tolerances.
4.3
Lead Wire Identification
The 5626 and 5628 PRTs are equipped with a four-wire cable. The same
used to cancel lead wire resistance. For best results, the readout device
should be equipped to handle four-terminal resistors.
RED
(Heat Shrink)
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.
9
5
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 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 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.
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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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.
12
6
Operation
6
Operation
6.1
General
For best results, be familiar with the operation of the heat source and the
read-out 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 (Rtp) after each temperature measurement. The following
equation provides the most accurate measurement of the ratio:
Rt
Rtp
Wt =
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.
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
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 re-
versible current.
14
7
Accessories
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 2602 PRT Protective Case for 5626-15, 5628-15,
5626-20, and 5628-20 PRT
7.2
PRT Termination
on the user’s requirements:
• Gold Plated Spade Lug
• Bare Wire
• 5-Pin Din Connector
Spade Lug
(standard)
Bare Wire
(customer option)
5-Pin DIN
(customer option)
5
4
1
2
3
Figure 4 Probe Termination Examples
15
8
Troubleshooting
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-
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
• Mechanical shock can cause temperature errors as great
as 0.5°C. If this is observed, first measure and record the
Rtp. Next anneal the PRT at 660°C overnight. Measure the
Rtp again. The annealing should decrease the Rtp. If the
Rtp is stable, recalibrate the PRT.
Data changes less than
0.1°C
• Slight mechanical shock can cause temperature errors
less than 0.1°C. If this is observed, first measure and re-
cord the Rtp. Next anneal the PRT at 660°C overnight.
Measure the Rtp again. The annealing should decrease
the Rtp. Repeat the annealing, Rtp measurement cycle
several times. When the Rtp is stable, recalibrate the PRT.
If the Rtp does not stabilize, contact an Authorized Hart
Scientific Service Center (see Section 1.3).
• Oxidation of the platinum sensor may occur after pro-
longed use between 200 – 450°C. This oxidation will
demonstrate itself by an increase in Rtp of less than
0.1°C. To reduce the effects of oxidation, anneal the PRT
at 600 – 661°C overnight (12 hr.). Measure the Rtp again.
Repeat the annealing, Rtp measurement cycle several
times This annealing process should return Rtp to within
calibration tolerances. If the Rtp is within calibration tol-
erance, the PRT is usable. If the Rtp is not within calibra-
tion tolerance, but it is stable, recalibrate the PRT.
Data unstable
• 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
• 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.
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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).
18
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