Apogee Instruments SI-4HR User manual

APOGEE INSTRUMENTS, INC. | 721 WEST 1800 NORTH, LOGAN, UTAH 84321, USA
TEL: [phone] | FAX: [phone] | WEB: APOGEEINSTRUMENTS.COM
Copyright © 2022 Apogee Instruments, Inc.
OWNER’S MANUAL
INFRARED RADIOMETER
Models SI-4HR
Rev: 31-Aug-2022

TABLE OF CONTENTS
Owner’s Manual ............................................................................................................................................................................... 1
Declarations of Conformity...................................................................................................................................................... 3
Introduction ............................................................................................................................................................................. 5
Sensor Models ......................................................................................................................................................................... 6
Specifications ........................................................................................................................................................................... 7
Deployment and Installation.................................................................................................................................................... 8
Cable Connectors................................................................................................................................................................... 10
Operation and Measurement ................................................................................................................................................ 11
Maintenance and Recalibration............................................................................................................................................. 19
Troubleshooting and Customer Support................................................................................................................................ 20
Return and Warranty Policy................................................................................................................................................... 21

DECLARATION OF CONFORMITY
EU Declaration of Conformity
This declaration of conformity is issued under the sole responsibility of the manufacturer:
Apogee Instruments, Inc.
721 W 1800 N
Logan, Utah 84321
USA
for the following product(s):
Models: SI-4HR
Type: Infrared Radiometer
The object of the declaration described above is in conformity with the relevant Union harmonization legislation:
2014/30/EU Electromagnetic Compatibility (EMC) Directive
2011/65/EU Restriction of Hazardous Substances (RoHS 2) Directive
2015/863/EU Amending Annex II to Directive 2011/65/EU (RoHS 3)
Standards referenced during compliance assessment:
EN 61326-1:2013 Electrical equipment for measurement, control, and laboratory use –EMC requirements
EN 63000:2018 Technical documentation for the assessment of electrical and electronic products with
respect to the restriction of hazardous substances
Please be advised that based on the information available to us from our raw material suppliers, the products
manufactured by us do not contain, as intentional additives, any of the restricted materials including lead (see
note below), mercury, cadmium, hexavalent chromium, polybrominated biphenyls (PBB), polybrominated
diphenyls (PBDE), bis (2-ethylhexyl) phthalate (DEHP), butyl benzyl phthalate (BBP), dibutyl phthalate (DBP), and
diisobutyl phthalate (DIBP). However, please note that articles containing greater than 0.1 % lead concentration
are RoHS 3 compliant using exemption 6c.
Further note that Apogee Instruments does not specifically run any analysis on our raw materials or end products
for the presence of these substances, but we rely on the information provided to us by our material suppliers.
Signed for and on behalf of:
Apogee Instruments, August 2022
Bruce Bugbee
President
Apogee Instruments, Inc.

DECLARATION OF CONFORMITY
UK Declaration of Conformity
This declaration of conformity is issued under the sole responsibility of the manufacturer:
Apogee Instruments, Inc.
721 W 1800 N
Logan, Utah 84321
USA
for the following product(s):
Models: SI-4HR
Type: Infrared Radiometer
The object of the declaration described above is in conformity with the relevant UK Statutory Instruments and
their amendments:
2016 No. 1091 The Electromagnetic Compatibility Regulations 2016
2012 No. 3032 The Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic
Equipment Regulations 2012
Standards referenced during compliance assessment:
BS EN 61326-1:2013 Electrical equipment for measurement, control, and laboratory use –EMC requirements
BS EN 63000:2018 Technical documentation for the assessment of electrical and electronic products with
respect to the restriction of hazardous substances
Please be advised that based on the information available to us from our raw material suppliers, the products
manufactured by us do not contain, as intentional additives, any of the restricted materials including lead (see
note below), mercury, cadmium, hexavalent chromium, polybrominated biphenyls (PBB), polybrominated
diphenyls (PBDE), bis (2-ethylhexyl) phthalate (DEHP), butyl benzyl phthalate (BBP), dibutyl phthalate (DBP), and
diisobutyl phthalate (DIBP). However, please note that articles containing greater than 0.1 % lead concentration
are RoHS 3 compliant using exemption 6c.
Further note that Apogee Instruments does not specifically run any analysis on our raw materials or end products
for the presence of these substances, but we rely on the information provided to us by our material suppliers.
Signed for and on behalf of:
Apogee Instruments, August 2022
Bruce Bugbee
President
Apogee Instruments, Inc.

INTRODUCTION
All objects with a temperature above absolute zero emit electromagnetic radiation. The wavelengths and intensity
of radiation emitted are related to the temperature of the object. Terrestrial surfaces (e.g., soil, plant canopies,
water, snow) emit radiation in the mid infrared portion of the electromagnetic spectrum (approximately 4-50 µm).
Infrared radiometers are sensors that measure infrared radiation, which is used to determine surface temperature
without touching the surface (when using sensors that must be in contact with the surface, it can be difficult to
maintain thermal equilibrium without altering surface temperature). Infrared radiometers are often called infrared
thermometers because temperature is the desired quantity, even though the sensors detect radiation.
Typical applications of infrared radiometers include plant canopy temperature measurement for use in plant water
status estimation, road surface temperature measurement for determination of icing conditions, and terrestrial
surface (soil, vegetation, water, snow) temperature measurement in energy balance studies.
Apogee Instruments SI series infrared radiometers consist of a thermopile detector, germanium filter, precision
thermistor (for detector reference temperature measurement), and signal processing circuitry mounted in an
anodized aluminum housing, and a cable to connect the sensor to a measurement device. All radiometers also
come with a radiation shield designed to minimize absorbed solar radiation, but still allowing natural ventilation.
The radiation shield insulates the radiometer from rapid temperature changes and keeps the temperature of the
radiometer closer to the target temperature. Sensors are potted solid with no internal air space and are designed
for continuous temperature measurement of terrestrial surfaces in indoor and outdoor environments. SI-400
series sensors output a digital signal using SDI-12 protocol version 1.3.
The SI-4HR-SS infrared radiometer is developed for road weather networks specifically, with a 10° vertical field of
view, allowing for remote detection of a narrow and distant target roadway. The rectangular-shaped aperture
maximizes the horizontal field of view allowing for a larger integrated measurement without including undesired
target areas such as sky or surrounding terrain.

SENSOR MODELS
The FOV is shown below:
Model
Output
SI-400 Series
SDI-12
SI-100 Series
Voltage
A sensor’s model number and serial number are
located on a label near the pigtail leads on the
sensor cable. If the manufacturing date of a
specific sensor is required, please contact Apogee
Instruments with the serial number of the sensor.

SPECIFICATIONS
Calibration Traceability
Apogee SI series infrared radiometers are calibrated to the temperature of a custom blackbody cone held at
multiple fixed temperatures over a range of radiometer (detector/sensor body) temperatures. The temperature of
the blackbody cone is measured with replicate precision thermistors thermally bonded to the cone surface. The
precision thermistors are calibrated for absolute temperature measurement against a platinum resistance
thermometer (PRT) in a constant temperature bath. The PRT calibration is directly traceable to the NIST.
Spectral Response
SI-4HR-SS
Input Voltage Requirement
5.5 to 24 V DC
Current Drain
1.5 mA (quiescent), 2.0 mA (active)
Calibration Uncertainty (-30 to 65 C), when target and
detector temperature are within 20 C
0.3 C
Calibration Uncertainty (-40 to 80 C), when target and
detector temperate are different by more than 20 C
(see Calibration Traceability below)
0.5 C
Measurement Repeatability
Less than 0.05 C
Stability (Long-term Drift)
Less than 2 % change in slope per year when germanium filter is
maintained in a clean condition (see Maintenance and Recalibration
section below)
Response Time
0.6 s, time for detector signal to reach 95 % following a step change;
fastest data transmission rate for SDI-12 circuitry is 1 s
Field of View
5° vertical half angle; 16° horizontal half angle
Spectral Range
8 to 14 µm; atmospheric window (see Spectral Response below)
Operating Environment
-50 to 80 C; 0 to 100 % relative humidity (non-condensing)
Dimensions
23 mm diameter; 76 mm length
Mass
219 g (with 5m of lead wire)
Cable
5 m of two conductor, shielded, twisted-pair wire; TPR jacket (high
water resistance, high UV stability, flexibility in cold conditions);
pigtail lead wires; stainless steel (316), M8 connector located 25 cm
from sensor head
Spectral response of SI series infrared
radiometers. Spectral response (green line) is
determined by the germanium filter and
corresponds closely to the atmospheric window
of 8-14 µm, minimizing interference from
atmospheric absorption/emission bands (blue
line) below 8 µm and above 14 µm. Typical
terrestrial surfaces have temperatures that yield
maximum radiation emission within the
atmospheric window, as shown by the blackbody
curve for a radiator at 28 C (red line).

DEPLOYMENT AND INSTALLATION
The mounting geometry (distance from target surface, angle of orientation relative to target surface) is
determined by the desired area of surface to be measured. The field of view extends unbroken from the sensor to
the target surface. Sensors must be carefully mounted in order to view the desired target and avoid including
unwanted surfaces/objects in the field of view, thereby averaging unwanted temperatures with the target
temperature (see Field of View below). Once mounted, the green cap must be removed. The green cap can be
used as a protective covering for the sensor, when it is not in use.
An Apogee Instruments model AM-220 mounting bracket is recommended for mounting the sensor to a cross arm
or pole. The AM-220 allows adjustment of the angle of the sensor with respect to the target and accommodates
the radiation shield designed for all SI series infrared radiometers.

Field of View
The field of view (FOV) is reported as the half-angle of the apex of the cone formed by the target surface (cone
base) and the detector (cone apex), as shown below, where the target is defined as a circle from which 98 % of the
radiation detected by the radiometer is emitted.
Sensor FOV, distance to target, and sensor mounting angle in relation to the target will determine target area.
Different mounting geometries (distance and angle combinations) produce different target shapes and areas, as
shown below.
CIRCULAR
HORIZONTAL
FOV Area (m²)
Half Angle
FOV Area (m²)
Type
Model
Half Angle
0 Deg
45 Deg
60 Deg
Type
Model
Horizontal
Vertical
0 Deg
45 Deg
60 Deg
Standard
SI-111
22°
2.069
7.627
45.211
Standard
SI-1H1
32°
13°
2.276
7.148
45.512
Narrow
SI-121
18°
1.337
4.461
18.865
Narrow
SI-4HR
16°
5°
0.403
1.15
3.341
Ultra-Narrow
SI-131
14°
0.787
2.447
8.544
-
A simple FOV calculator for determining target dimensions based on infrared radiometer model, mounting height,
and mounting angle, is available on the Apogee website: https://www.apogeeinstruments.com/irr-calculators.

CABLE CONNECTORS
Apogee offers in-line cable connectors on some bare-
lead sensors to simplify the process of removing
sensors from weather stations for calibration (the
entire cable does not have to be removed from the
station and shipped with the sensor).
The ruggedized M8 connectors are rated IP68, made
of corrosion-resistant marine-grade stainless-steel,
and designed for extended use in harsh
environmental conditions.
Inline cable connectors are installed 30 cm from the
head
(pyranometer pictured)
Instructions
Pins and Wiring Colors: All Apogee connectors
have six pins, but not all pins are used for every
sensor. There may also be unused wire colors
inside the cable. To simplify datalogger connection,
we remove the unused pigtail lead colors at the
datalogger end of the cable.
If a replacement cable is required, please contact
Apogee directly to ensure ordering the proper
pigtail configuration.
Alignment: When reconnecting a sensor, arrows
on the connector jacket and an aligning notch
ensure proper orientation.
Disconnection for extended periods: When
disconnecting the sensor for an extended period of
time from a station, protect the remaining half of
the connector still on the station from water and
dirt with electrical tape or other method.
A reference notch inside the connector ensures
proper alignment before tightening.
When sending sensors in for calibration, only send the
short end of the cable and half the connector.
Tightening: Connectors are designed to be firmly
finger-tightened only. There is an O-ring inside the
connector that can be overly compressed if a
wrench is used. Pay attention to thread alignment
to avoid cross-threading. When fully tightened, 1-2
threads may still be visible.
Finger-tighten firmly