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Sensors and Accessories (Volume 1)
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Series 68 Platinum RTD
January 2015
Rosemount Series 68 Platinum Resistance Temperature Sensors
measure from –50 to 400 °C (–58 to 752 °F). Series 68 Class B,
Pt100-385 sensors are available in capsule, general purpose, and
spring-loaded designs in sensor lengths from 1 to 48 inches.
Table 21 shows the interchangeability of the Series 68 RTD. As
an option, for maximum system accuracy, Emerson Process
Management can provide sensor calibration. See Sensor
characterization (calibration) schedules– Option Code V . In
addition, Emerson Process Management offers optional
sensor-to-transmitter matching capability obtainable through
the use of Callendar-Van Dusen Constants. See Option Code “V”
Callendar-van Dusen Constants .
Table 21. Series 68 Interchangeability
±0.55 °C (±0.99 °F) at -50 °C (-58 °F)
±0.30 °C (±0.54 °F) at 0 °C (32 °F)
±0.80 °C (±1.44 °F) at 100 °C (212 °F)
±1.30 °C (±2.34 °F) at 200 °C (392 °F)
±1.80 °C (±3.24 °F) at 300 °C (572 °F)
±2.30 °C (±4.14 °F) at 400 °C (752 °F)
Construction
Figure 7. Construction of a Platinum Thin Film RTD
Platinum element and lead wire
configurations
Single-element temperature sensors have four lead wires and
may be used in 2-, 3-, and 4-wire signal conditioning systems.
Specifications
Performance specifications
Temperature range
–50 to 400 °C (–58 to 752 °F)
Effect of temperature cycling
±0.05% (0.13 °C or 0.23 °F) maximum ice-point resistance shift
following 10 cycles over the specified temperature range
Stability
±0.11% 0.28 °C or 0.51 °F maximum ice-point resistance shift
following 1,000 hours at maximum specified temperature
(400 °C)
Maximum hysteresis
±0.1% of operating temperature range
Time constant
A. Connection Seal
B. Connection Pads
C. Connection Leads
D. Passivation with Glass Layers
Design and construction of the Series 68 Platinum Sensors
provides the optimum combination of accuracy and durability
available for temperature measurements. The construction of
the sensor allows for direct immersion in non-corrosive fluids at
reasonable static pressures. For corrosive environments or many
industrial applications, these sensors are widely used with
standard thermowell assemblies.
E. Photolithography Structured
Platinum Thin Film
F. Ce ra mic Su bs trat e
12 seconds maximum required to reach 63.2% sensor response
in water flowing at 3 ft/s (0.91 m/s)
Nominal R0 100 Ohm
Nominal alpha 0.00385 Ω/Ω°C
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Sensors and Accessories (Volume 1)
Physical specifications
Material selection
Emerson provides a variety of Rosemount product with various
product options and configurations including materials of
construction that can be expected to perform well in a wide
range of applications. The Rosemount product information
presented is intended as a guide for the purchaser to make an
appropriate selection for the application. It is the purchaser’s
sole responsibility to make a careful analysis of all process
parameters (such as all chemical components, temperature,
pressure, flow rate, abrasives, contaminants, etc.), when
specifying product, materials, options and components for the
particular application. Emerson Process Management is not in a
position to evaluate or guarantee the compatibility of the
process fluid or other process parameters with the product,
options, configuration or materials of construction selected.
Sheath material
316 SST and 321 SST
Lead wire
PTFE insulated, silver plated, 24-gauge stranded copper wire
Environmental specifications
Humidity limits
Lead seal can withstand 100% relative humidity
Vibration limits
±0.05% maximum ice-point resistance shift due to 30 minutes of
14 g peak vibration from 5 to 350 Hz at 20 °C (68 °F) for
unsupported stem length of less than 6 inches
Quality assurance
Each sensor is subjected to a resistance accuracy test at
0 °C and an insulation resistance test
Enclosure ratings
When installed properly, Rosemount Series 68 sensors are
suitable for indoor and outdoor NEMA 4X and CSA Enclosure
Type 4X installations. See Hazardous area approvals for
complete installation information
Insulation resistance
1000 x 10
measured at 500 Vdc at room temperature
6
ohms minimum insulation resistance when
Identification data
The model, serial numbers, and up to six lines of permanent
tagging information are etched on each sensor adapter.
Stainless steel tags are available upon request.
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Sensors and Accessories (Volume 1)
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Series 78 Platinum RTD
January 2015
Series 78 Sensors are intended for applications that require high
accuracy, dual-elements, and/or are subjected to high
temperatures. Series 78 Platinum Resistance Temperature
Sensors measure from –200 to 600 °C (–328 to 1112 °F). These
sensors are available in capsule, general-purpose, and
spring-loaded in sensor (X) lengths from 1 to 68 inches. They are
also available bayonet spring-loaded style in sensor (X) lengths
from 1 to 45 inches.
Ta bl e shows the interchangeability of the Series 78 Pt100-385
Sensors. The performance of the standard Series 78 Sensor
conforms to the standard set by IEC 751 Class B. Additionally,
IEC-751 Class A accuracy is available as an option. For maximum
system accuracy, Emerson Process Management can provide
sensor calibration. See Sensor characterization (calibration)
schedules– Option Code V . Emerson Process Management also
offers optional sensor-to-transmitter matching capability
obtainable through the use of Callendar-Van Dusen Constants.
See Option Code “V” Callendar-van Dusen Constants and Graph
of a Typical Two-Point Trim
The wire-wound design and construction of the
general-purpose Series 78 Sensor allows direct immersion in
non-corrosive fluids at reasonable static pressures. For corrosive
environments and in many industrial applications, these sensors
are commonly used with standard thermowell assemblies.
Platinum element and lead wire
configurations
Single-element high-temperature sensors have four lead wires
and may be used in 2-, 3-, and 4-wire signal conditioning
systems.
Dual-element sensors have redundant elements to provide
separate readout and control signals from a single measurement
point. Dual-element sensors have three lead wires for each
element and may be used with 2- or 3-wire systems.
Figure 8. Lead Wire Configuration
Single element Dual element
(1)
Figure 9. Construction of a Platinum Wire-Wound RTD
A. Lead Wires
B. Seal
C. High Purity Insulator
D. Platinum Resistance Element
Specifications
Performance specifications
Temperature range
Series 78 single- and dual-element sensors may be used in
temperatures from –200 to 500 °C (–328 to 932 °F). Series 78
single-element high-temperature sensors are provided for
high-temperature service over the range of 0 to 600 °C (32 to
1112 °F).
Effect of temperature cycling
±0.04% (0.10 °C or 0.18 °F) maximum ice-point resistance shift
following 10 cycles between –200 and 500 °C (–328 to 932 °F).
Stability
±0.05% maximum ice-point resistance shift following
1,000 hours at 400 °C (752 °F).
(1) Dual element sensors are only available on Series 68Q and 78 Sensors.
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Sensors and Accessories (Volume 1)
Table 22. Series 78 Interchangeability
(1)(2)
Standard series 78 IEC-751 Class B Temperature
±0.80 °C (±1.44 °F) -100 °C (-148 °F)
±0.30 °C (±0.54 °F) 0 °C (32 °F)
±0.80 °C (±1.44 °F) 100 °C (212 °F)
±1.80 °C (±3.24 °F) 300 °C (572 °F)
±2.30 °C (±4.14 °F) 400 °C (752 °F)
Series 78 with IEC-751 Class A option Temperature
±0.35 °C (±0.63 °F) -100 °C (-148 °F)
±0.15 °C (±0.27 °F) 0 °C (32 °F)
±0.35 °C (±0.63 °F) 100 °C (212 °F)
±0.75 °C (±1.35 °F) 300 °C (572 °F)
±0.95 °C (±1.71 °F) 400 °C (752 °F)
(1) Both tolerances valid from -200 to 500 °C.
(2) Class B tolerances valid from 0 to 600 °C on single- element high
temperature sensor.
Maximum hysteresis
Single- and dual-element, Nominal R0 100 Ohm Nominal
alpha 0.00385 Ω/Ω °C: +/- 0.04% of range
Single-element, high temperature: ±0.1% of range.
Time constant
4 seconds maximum required to reach 63.2% sensor response in
water flowing at 3 ft/s (0.91 m/s), 9.5 seconds for
single-element high-temperature sensors.
Environmental specifications
Humidity limits
Lead seal is capable of withstanding 100% relative humidity.
Vibration limits
Standard single- and dual-element sensors
±0.03% maximum ice-point resistance shift due to 30
minutes of 21 g peak vibration from 5 to 350 Hz
continuous sweep at 20 °C (68 °F) for unsupported stem
length of less than 5.5 inches (140 mm).
Single-element high-temperature sensors
Meet ASTM E 1137-95. Cycling time is 3 hours per
longitudinal axis, less the time spent at resonant dwells at
the axis, from 5 to 500 Hz. The test level is 1.27 mm (0.05
in.) double amplitude displacement or peak g-level of 3,
whichever is less.
Quality assurance
Each sensor is subjected to a resistance accuracy test at 0 °C and
an insulation resistance test.
Enclosure ratings
When installed properly, Rosemount Series 78 Sensors are
suitable for indoor and outdoor NEMA 4X and CSA Enclosure
Type 4X installations. See Hazardous area approvals for
complete installation information.
Physical specifications
Sheath material
Single and dual-element, 316 SST
Self heating
18 mW minimum power dissipation required to cause a 1 °C
(1.8 °F) temperature measurement error in water flowing at
3 ft/s, 25 mW for single-element high temperature sensors.
Insulation resistance
6
500 x 10
ohms minimum insulation resistance when measured
at 500 Vdc at room temperature [20 °C (68 °F)].
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Single element high temperature, 316SST and 321 SST
Lead wires
Single and dual-element, PTFE-insulated, nickel-coated,
22-gauge stranded copper wire.
Single element high temperature, PTFE insulated, silver
plated, 24-gauge stranded copper wire.
Identification data
The model and serial numbers and up to six lines of permanent
tagging information are etched on each sensor adapter.
Stainless steel tags are available upon request.
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