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COMPONENTS
ASPTC
Aspirated Thermocouple
Highly Accurate Air
Temperature
Fine-wire thermocouple in
aspirated radiation shield
Overview
The ASPTC* consists of a type-E ne-wire thermocouple mounted in a fan-aspirated radiation shield to provide highly accurate
air temperature measurements. One ASPTC can measure abso-
Benets and Features
Uses ne-wire thermocouple for accurate air temperature
measurements
Technical Description
Aspirated Radiation Shield
The ASPTC’s radiation shield is an elongated tube constructed
from white UV-stabilized polyethylene that provides low thermal conductivity and heat retention. A fan draws air across the
measurement junction, which reduces solar loading on the thermocouple. The radiation shield also protects the thermocouple,
increasing the thermocouple’s durability.
Thermocouple
The ASPTC’s thermocouple is comprised of a chromel wire and
a constantan wire joined at a measurement junction. A voltage potential is generated when the measurement end of the
lute air temperature, or two ASPTCs can make delta temperature
measurements. Often, the ASPTC replaces, or is measured in addition to, the TCBR thermocouples in a Bowen ratio system.
Includes aspirated radiation shield
High-powered fan reduces solar loading
thermocouple is at a dierent temperature than the reference end
of the thermocouple. The magnitude of the voltage potential is
related to the temperature dierence. Therefore, temperature can
be determined by measuring the dierences in potential created
at the junction of the two wires
A reference temperature measurement (typically measured at the
datalogger wiring panel) is required. Options for measuring the
reference temperature include:
Thermistor built into the CR800, CR850, CR1000, CR3000, or
CR5000 wiring panel
PRT built into the wiring panel of the CR9050 or CR9051E input
module for the CR9000X Measurement and Control System
*e ASPTC is not compatible with our CR200(X)-series or CR510 dataloggers.
questions & quotes: 435.227.9000
campbellsci.com/asptc
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Campbell Scientic, Inc.
815 W 1800 N
Logan, UT 84321-1784
(435) 227-9000
www.campbellsci.com
Mounting
The ASPTC can be mounted to a tripod or tower via the UT018-5
crossarm or a user-supplied crossarm that has a square cross section of 3.8 cm by 3.8 cm (1.5 inch by 1.5 inch).
Power Considerations
The ASPTC is typically powered with a user-supplied deep cycle
battery that is recharged with an SP20R, SP50, or SP90 solar panel;
for high current drain systems two SP90 solar panels may be used
to provide 180 W of power. The datalogger’s rechargeable battery can only be used if it is connected to ac power. For help on
analyzing your system’s power requirements, refer to our Power
Supply brochure or application note.
Specications
Shield Material: UV stabilized polyethylene
Power Cable Diameter: 0.5 cm (0.2 in)
Signal Cable Diameter: 0.3 cm (0.1 in)
Weight: 0.86 kg (1.9 lb)
Thermocouple
Type: Chromel-Constantan
Diameter: 0.0762 mm (0.003 in)
Typical Output: 60 μV/°C
Accuracy: Refer to the Thermocouple Measurement section
in your datalogger manual
Ordering Information
Aspirated Thermocouple
ASPTC Aspirated Thermocouple with Radiation Shield.. Must specify
signal and power cable lengths (see below).
Cable Lengths
-L After the -L, enter the signal cable length in feet. A 15-ft
length is typically used.
-LP After the -LP, enter the power cable length in feet. A 15-ft
length is typically used.
Mounts
UT018 -5 Tower Mounting Bracket with 5-ft Crossarm
Fan
Air Velocity at Thermocouple: 5.5 m at 12 Vdc
Life Expectancy: 65,000 hr at 30°C
Current Drain: 260 mA at 12 Vdc
Operating Voltage Range: 9 to 13 Vdc
Operating Temperature Range: -10° to 70°C
Reverse Polarity Protected
←
4.6 cm (1.8 in) O.D.
↓
↓
thermocouple
USA | AUSTRALIA | BRAZIL | CANADA | CHINA | COSTA RICA | ENGLAND | FRANCE | GERMANY | SOUTH AFRICA | SPAIN
mounting bracket
power cable
|
53.3 cm (21 in)
|
→
|
↕
signal cable
|
5.8 cm (2.3 in) O.D.
↑
14.7 cm
(5.8 in)
↓
Campbell Scientic, Inc.
© 2005, 2013
August 5, 2013
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