Fluke 5680 User manual

5680/5682/5699
Metal Sheath Standard
Platinum Resistance Thermometer
User’s Guide
Rev. 5C1301
Hart Scientific
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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 Authorized Service Centers. . . . . . . . . . . . . . . . . . . . . . 3
2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3.1 Calibration Intervals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.4 Recalibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.5 Return Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3 Specifications and Warranty . . . . . . . . . . . . . . . . . . . 9
3.1 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.2 Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.3 Electrical Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.4 Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.1 Environmental Issues . . . . . . . . . . . . . . . . . . . . . . . . 11
4.2 Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.3 Lead Wire Identification. . . . . . . . . . . . . . . . . . . . . . . 11
5 SPRT Care and Handling Guidelines . . . . . . . . . . . . . . 13
5.1 SPRT Care. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.2 SPRT Handling Guidelines . . . . . . . . . . . . . . . . . . . . . 13
6 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
6.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
6.2 Comparison Calibration of Other Instruments . . . . . . . . . . . 15
6.3 Immersion Requirements . . . . . . . . . . . . . . . . . . . . . . 15
6.4 Thermal EMF . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
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6.5 Measuring Current . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.6 Cooling Rates at High Temperatures . . . . . . . . . . . . . . . . 16
7 Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
7.1 Case . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8 Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . 21
8.1 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
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Figures and Tables
Table 1 International Electrical Symbols . . . . . . . . . . . . . . . . . . . . . 1
Figure 1 5680/5682/5699 Metal Sheath Platinum Resistance Thermometer . . . . 5
Table 2 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 2 Circuit Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
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1 Before You Start
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.
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
1 Before You Start
Symbols Used
Table 1 International Electrical Symbols
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Symbol Description
Canadian Standards Association
OVERVOLTAGE (Installation) CATEGORY II, Pollution Degree 2 per IEC1010-1 re-
fers to the level of Impulse 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
The European Waste Electrical and Electronic Equipment (WEEE) Directive
(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 in-
strument being used.
1.2.1 WARNINGS
To avoid personal injury, follow these guidelines.
•DO NOT use this instrument to measure the temperature of any hazard-
ous 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.
5680/5682/5689 SPRT
User’s Guide
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•Read Section entitled “SPRT Care and Handling Guidelines” before re-
moving the SPRT from the shipping box or case. Incorrect handling can
damage the SPRT and void the warranty.
•Keep the shipping container in case it is necessary to ship the SPRT. In-
correct packaging of the SPRT for shipment can cause irreparable dam-
age.
1 Before You Start
Authorized Service Centers
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2 Introduction
2.1 General
The Hart Metal Sheath Standard Platinum Resistance Thermometer (SPRT) is
designed to be an excellent primary standard interpolating instrument convert-
ing temperature to resistance. Hart Scientific offers three models (5680, 5682,
and 5699). Models 5680 and 5682 metal sheath SPRTs cover the International
Temperature Scale of 1990 (ITS-90) range from below the Triple Point of Ar-
gon (–189°C) to 480°C. The 5699 metal sheath SPRT covers the ITS-90 range
from below the Triple Point of Argon (–189°C) to 661°C. The 5680 has a resis-
tance of 25Ωat the triple point of water (0.01°C), the 5682 has a resistance of
100Ωat the triple point of water, and the 5699 has a resistance of 25.5Ωat the
triple point of water.
These metal sheath SPRTs are hand constructed at Hart Scientific by experts
with years of SPRT manufacturing experience. Each SPRT is carefully an-
nealed 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 special frame. The 5680 and 5682 sensors are protected by a
ceramic capsule. The 5699 sensor is protected by a platinum capsule. The sen-
sors are pressure sealed with a special argon/oxygen mixed gas and fit with a
terminal box handle with a strain relieved connection to the five wire cable.
Gold plated spade lugs terminate the wires.
5
2 Introduction
General
Figure 1 5680/5682/5699 Metal Sheath Platinum Resistance Thermometer
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2.2 Application
Hart Scientific metal sheath SPRTs are classified as primary standards. A pri-
mary standard is defined in terms of transfer of the ITS-90 from a standards
laboratory to a customer’s laboratory. Primary standards are calibrated in a
standards lab using known intrinsic values.
2.3 Calibration
In order for any instrument to be used as a standard it must be calibrated. The
SPRT may be purchased calibrated or non-calibrated. Hart has the capability to
perform fixed-point or comparison calibrations traceable to NIST. They can be
economically calibrated using the comparison method or any one of several
fixed-point calibrations matching ITS-90 subranges.
2.3.1 Calibration Intervals
Accuracy required for the application and the condition of use dictate the cali-
bration intervals. Calibration checks at the triple point of water should be ac-
complished periodically and the results recorded. Once a written history of the
SPRT is available, calibration intervals can be adjusted. The SPRT does not
need to be recalibrated as long as the change in resistance does not exceed the
owner’s specifications.
Depending on the user’s Quality Assurance requirements, the SPRT 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 cali-
bration tolerances, a full recalibration should be scheduled.
2.4 Recalibration
The recalibration of the SPRTs should be scheduled according to the user’s
company Quality Assurance requirements. Normally, an SPRT is recalibrated
annually. Unless the SPRT is used only over a limited range, calibration over
the full range of the SPRT (–200°C to 480°C for the 5680 and 5682, and
–200°C to 661°C for the 5699) is recommended. For information on
recalibrating your SPRT, contact a Hart Scientific Authorized Service Center
(see Section 1.3) for calibration options, an RMA number, and current pricing.
2.5 Return Procedure
Call an Authorized Service Center for an RMA number before shipping.
Extreme care must be taken in shipping a SPRT. Place the thermometer in its
factory provided protective storage case. Be sure the case is latched securely.
Place the protective case in the original manufacturer’s wooden shipping crate
or wooden crate with similar dimensions (44 1/2 in. x 11 3/4 in. x 11 3/4 in.).
5680/5682/5689 SPRT
User’s Guide
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Place soft insulation on all sides of the crate to cushion the SPRT against me-
chanical shocks. The cover of the crate should be attached with screws. Label-
ing as extremely fragile is recommended.
Whether the thermometer is returned for repair or warranty, please include a
letter containing the following information
•Description of the faulty operation and circumstances of failure.
•Complete shipping instructions for the return of the thermometer to the
customer.
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2 Introduction
Return Procedure
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3 Specifications and Warranty
3.1 Specifications
5680 5682 5699
Temperature Range –200°C to 480°C –200°C to 661°C
Resistance Value at TPW 25.5
Ω ±0.5 Ω 100 Ω ±1.0 Ω 25.5 Ω ±0.5 Ω
Specified Current 1 mA 1 mA or 0.5 mA 1mA
Resistance Ratio W(234.3156K)
≤ 0.844235
W(302.9146K)
≥ 1.11807
Sensitivity 0.1
Ω /°C 0.4 Ω /°C 0.1 Ω /°C
Stability <0.010°C/100 hours at 480°C
(typically < 0.005°C)
<8 mK per year max
(typically 2–3 mK per
year)
Repeatability < 2mK < 1mK
Diameter of Pt Sensor
Wire
0.07 mm (0.003") 0.04 mm (0.0016") 0.07 mm (0.003")
Lead Wires 5: four sensor wires plus grounding wire
Protective Sheath Inconel™600
Diameter: 6.35 mm (0.25")
Length: 485 mm (19.1")
Inconel™600
Diameter: 5.56 mm ±0.13
mm (0.219" ±0.005")
±0.127 mm (0.005")
Length: 482 mm (19")
Insulation Resistance > 100M
Ω at 480°C
>1000M
Ω at 20°C
> 100M
Ω at 661°C
>1000M
Ω at 20°C
3.2 Construction
The Model 5680/5682 SPRTs cover the range from –200°C to 480°C and the
Model 5699 SPRT covers the range from –200°C to 661°C. The sensor ele-
ments are crafted using high purity platinum wire wound in a strain free design
on a specially designed support.
3.3 Electrical Circuit
The metal sheathed SPRTs are provided with a terminal box handle. The
eight-foot cable has five polyethylene coated wires enclosed in a super-flex
rubber jacket with a stainless steel spring strain relief. Gold plated spade lugs
terminate the wires. The fifth wire is a ground wire which is connected to the
Inconel sheath.
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3 Specifications and Warranty
Specifications
Table 2 Specifications
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3.4 Warranty
Fluke Corporation, Hart Scientific Division (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 warranty 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 instruc-
tions 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 condi-
tions or operation or handling, Hart will repair the product and bill the pur-
chaser for the reasonable cost of repair.
To exercise this warranty, the purchaser must forward the product after calling
or writing an Authorized Service Center for authorization. The Service Center
assumes NO risk for in-transit damage.
THE FOREGOING WARRANTY IS PURCHASER’S SOLE AND EXCLU-
SIVE REMEDY AND IS IN LIEU OF ALL OTHER WARRANTIES, EX-
PRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY
IMPLIED WARRANTY OR MERCHANTABILITY, OR FITNESS FOR ANY
PARTICULAR PURPOSE OR USE. HART SHALL NOT BE LIABLE FOR
ANY SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL DAM-
AGES OR LOSS WHETHER IN CONTRACT, TORT, OR OTHERWISE.
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User’s Guide
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4 Installation
4.1 Environmental Issues
Primary standard 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
4.2 Mounting
Most often temperature standards, primary and secondary, are used to calibrate
other temperature-sensitive equipment.
The SPRT must be mounted carefully to avoid any damage to the sensor. If the
fluid bath used does not have a lid designed for SPRT insertion, clamps should
be used to ensure that 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.
4.3 Lead Wire Identification
The Model 5680/5682/5699 SPRTs are equipped with a five-wire cable. Four
lead wires are used to cancel lead wire resistance. The fifth wire is a ground
wire which is connected to the Inconel sheath. For best results, the readout de-
vice should be equipped to handle four-terminal resistors.
The lead wire colors are red, black, white, yellow, and green. Lead wire pairs,
attached to each end of the sensor, are identified by heat shrink tubing. Red and
black wires have red heat shrink tubing. Blue and white wires have black heat
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4 Installation
Environmental Issues
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shrink tubing. The green wire is the ground wire which should be connected to
the ground. See Figure 2.
5680/5682/5689 SPRT
User’s Guide
12
BLACK RED
White
Yellow
Red
Black
R
x
GREEN
connected to Inconel sheath
to ground
Figure 2 Circuit Schematic
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5 SPRT Care and Handling Guidelines
5.1 SPRT Care
CAUTION: READ THIS SECTION BEFORE REMOVING THE SPRT
FROM THE SHIPPING BOX OR CASE
The 5680/5682/5699 Standard Platinum Resistance Thermometers (SPRTs) are
extremely delicate instruments. Great care must be taken when handling the
SPRT to maintain the calibration accuracy. Vibration or shock may cause the
resistance to increase. A slight tap to the SPRT tip as it is removed from an in-
strument can cause a change in Rtp as high as 1 mK. Correct handling of the
SPRT will prolong the life expectancy. When not in use, the SPRT should be
stored in the protective case provided by Hart Scientific.
5.2 SPRT Handling Guidelines
1. DO keep the thermometer as clean as possible. Always remove any fluid
from the sheath immediately after taking the thermometer from a bath.
2. DO immerse the thermometer in the appropriate liquid for the tempera-
ture range. If a dry block is used, the well diameter should allow the
SPRT to comfortably slip in and out without excess movement. For best
results, immerse the thermometer as deep as possible to avoid “stem ef-
fect” (the temperature error caused by the conduction of heat away from
the sensor). Do not submerge the handles.
3. DO allow sufficient time for the thermometer to stabilize before making
measurements allowing for the best accuracy.
4. DO use the correct drive current with the thermometer to prevent error in
temperature or resistance.
5. DO anneal the thermometer at 480°C for the 5680 and 5682, and at
661°C for the 5699 when it has been subjected to mechanical or temper-
ature shock. The SPRT should also be annealed before calibration.
6. DO use the protective case provided or other protection when the ther-
mometer is not in use.
7. DON’T subject the thermometer to any physical shock or vibration.
8. DON’T subject the thermometer to temperatures above the highest spec-
ified operating temperature.
9. DON’T expose the thermometer’s handle or cables to extreme
temperatures.
10. DON’T submerge the handle or cable in liquids.
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5 SPRT Care and Handling Guidelines
SPRT Care
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Model 5699 only
11. DO anneal the SPRT after delivery or when using at a temperature
higher than 600°C.
12. DON’T take the SPRT out directly when it has been at a temperature
higher than 500°C. Allow the SPRT to cool to a temperature less than
500°C before removing it to room temperature. See Section 6.6 for more
information.
5680/5682/5689 SPRT
User’s Guide
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6 Operation
6.1 General
For best results, be familiar with the operation of the calibration bath or furnace
and the read-out instrument. Be sure to follow the manufacturer’s instructions
for the read-out instrument and the calibration bath or furnace.
6.2 Comparison Calibration of Other Instruments
The uniformity and stability of the bath and the degree of accuracy required de-
termine the number of temperature measurements necessary. However, to fol-
low “good” practice procedures, always measure the triple point of water (Rtp)
after each temperature measurement. This provides the most accurate measure-
ment of the ratio:
Wt Rt
Rtp
() ()
()
=
Equation 1: Resistance Ratio Equation
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. How-
ever, the effect of the shunt resistance is insignificant. Full immersion is recom-
mended in a furnace or freeze point cell.
The immersion depth for primary standards is dependent on several factors in-
cluding accuracy requirements and type of liquid. Therefore, we recommend a
203 mm (8 inch) minimum immersion depth.
The exact immersion depth required can be determined by performing a gradi-
ent test taking measurements approximately every 127 mm (0.5 inch) 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 con-
sistency. Variations in chemical structure and discrepancies in crystal structure
due to impurities can contribute to thermal EMF. These factors are minimized
by annealing the full length of wire before construction of the SPRT.
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 tempera-
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6 Operation
General
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ture 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 can-
celed by using an AC bridge or a DC bridge with reversible current.
6.5 Measuring Current
Each SPRT has a specified drive current depending upon the particular sensor.
The recommended currents are in the following table.
Model Resistance Drive Current
5680 25
Ω
1.0 mA
5682 100
Ω
0.5 mA or 1.0 mA
5699 25
Ω
1.0 mA
Errors caused by self-heating of the element need to be minimized. Allowing
sufficient time for the SPRT to stabilize and the heat to be dispersed into the
surrounding medium will provide the most accurate results.
The Model 5680/5682/5699 measurements are made at 1 mA and 1.4 mA.
These measurements are then extrapolated to zero current. This can be done
graphically by plotting i² vs. R and extrapolating to zero power or by using the
following equation.
RR
iR R
ii
01
1
2
21
2
2
1
2
=− −
−
()
where:
R0= Zero current resistance
R1= Resistance measured at current i1
R2= Resistance measured at current i2
Equation 2: Calculation of R0
6.6 Cooling Rates at High Temperatures
The equilibrium concentration of point defects in the pure platinum wire in-
crease exponentially to the increase in temperature. If a high cooling rate (i.e.,
removing a SPRT from a high temperature and cooling it to room temperature
in less than a minute) occurs above 500°C, some of the point defects in the
platinum wire become trapped in the crystalline structure causing a slight in-
crease in resistance. This slight increase in resistance can be reversed by an-
nealing the SPRT. To avoid this problem, slowly cool the SPRT at a rate of
roughly 150°C/hour above 500°C before removing to room temperature. The
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User’s Guide
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SPRT can be safely removed from an instrument at 500°C or less and cooled to
room temperature without concern for the cooling rate.
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6 Operation
Cooling Rates at High Temperatures
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7 Accessories
7.1 Case
The SPRTs are shipped in a protective case. The SPRT should be stored in this
case when not in use. The SPRT should be shipped in this case when returning
(see Section 2.5, Return Procedure).
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7 Accessories
Case
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