COMPONENTS
ASPTC
Aspirated Thermocouple
Overview
The ASPTC* consists of a type-E fine-wire thermocouple mount-
ed in a fan-aspirated radiation shield to provide highly accurate
air temperature measurements. One ASPTC can measure abso-
lute air temperature, or two ASPTCs can make delta temperature
measurements. Often, the ASPTC replaces, or is measured in addi-
tion to, the TCBR thermocouples in a Bowen ratio system.
campbellsci.com/asptc
Benefits and Features
Uses fine-wire thermocouple for accurate air temperature
measurements
Includes aspirated radiation shield
High-powered fan reduces solar loading
questions & quotes:
435.227.9000
Technical Description
Aspirated Radiation Shield
The ASPTC’s radiation shield is an elongated tube constructed
from white UV-stabilized polyethylene that provides low ther-
mal conductivity and heat retention. A fan draws air across the
measurement junction, which reduces solar loading on the ther-
mocouple. 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 volt-
age potential is generated when the measurement end of the
thermocouple is at a different temperature than the reference end
of the thermocouple. The magnitude of the voltage potential is
related to the temperature difference. Therefore, temperature can
be determined by measuring the differences 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
Highly Accurate Air
Temperature
Fine-wire thermocouple in
aspirated radiation shield
*The ASPTC is not compatible with our CR200(X)-series or CR510 dataloggers.
