Apogee Instruments SU-221 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
ULTRAVIOLET-A SENSOR
Models SU-221
Rev: 26-Oct-2022

TABLE OF CONTENTS
Owner’s Manual ............................................................................................................................................................................... 1
Certificates of Compliance ....................................................................................................................................................... 3
Introduction ............................................................................................................................................................................. 5
Sensor Models ......................................................................................................................................................................... 6
Specifications ........................................................................................................................................................................... 7
Deployment and Installation.................................................................................................................................................. 10
Cable Connectors................................................................................................................................................................... 11
Operation and Measurement ................................................................................................................................................ 12
Maintenance and Recalibration............................................................................................................................................. 17
Troubleshooting and Customer Support................................................................................................................................ 18
Return and Warranty Policy................................................................................................................................................... 19

CERTIFICATE OF COMPLIANCE
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: SU-221
Type: Ultraviolet-A Sensor
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, October 2022
Bruce Bugbee
President
Apogee Instruments, Inc.

CERTIFICATE OF COMPLIANCE
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: SU-221
Type: Ultraviolet-A Sensor
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, October 2022
Bruce Bugbee
President
Apogee Instruments, Inc.

INTRODUCTION
Ultraviolet (UV) radiation constitutes a portion of the electromagnetic spectrum from 100 to 400 nm and is further
subdivided into three wavelength ranges: UV-A (315 to 400 nm), UV-B (280 to 315 nm), and UV-C (100 to 280 nm).
Much of the UV-B and all of the UV-C wavelengths from the sun are absorbed by Earth’s atmosphere. There are
also multiple artificial UV light sources available.
Most UV sensors designed for sunlight measurements are sensitive to UV radiation in the UV-A or UV-B ranges.
Apogee Instruments SU-200 series UV-A sensors detect UV radiation from 300 to 400 nm and are calibrated in
energy flux density units of watts per square meter (W m-2, equal to Joules per second per square meter). The
output can also be expressed in photon flux density units of micromoles per square meter per second (µmol m-2 s-
1).
Typical applications of UV sensors include incoming UV radiation measurement in outdoor environments or in
laboratory use with artificial light sources (e.g., germicidal lamps).
Apogee Instruments SU-200 series UV-A sensors consist of a cast acrylic diffuser, photodiode, and signal processing
circuitry mounted in an anodized aluminum housing and a cable to connect the sensor to a measurement device.
SU-200 sensors are designed for continuous UV-A radiation measurement in indoor or outdoor environments. The
SU-200 series outputs an analog voltage that is directly proportional to UV-A radiation incident on a planar surface
(does not have to be horizontal) where the radiation emanates from all angles of a hemisphere. SU-221 sensors
output a digital signal using SDI-12 communication protocol.

A sensor’s model number and serial number are
located on the bottom of the sensor. If you need
the manufacturing date of your sensor, please
contact Apogee Instruments with the serial number
of your sensor.
SENSOR MODELS
This manual covers the SDI-12 protocol UV-A sensor model SU-221 (in bold below). Additional models are covered
in their respective manuals.
Model
Signal
SU-200
0-10 mV
SU-202
0- 2.5 V
SU-205
0- 5 V
SU-221
SDI-12

SPECIFICATIONS
Calibration Traceability
Apogee UV series sensors are calibrated through side-by-side comparison to the mean of four transfer standard UV
sensors under UV-enhanced T5 fluorescent tubes. The transfer standard UV sensors are calibrated through side-
by-side comparison to an Apogee model PS-300 spectroradiometer under sunlight (clear sky conditions) in Logan,
Utah. The PS-300 is calibrated with a quartz halogen lamp traceable to the National Institute of Standards and
Technology (NIST).
SU-221-SS
Power Supply
5.5 to 24 V DC
Current Draw
1.4 mA (quiescent), 1.8 (active)
Calibration Factor
Custom for each sensor and stored in the firmware
Calibration Uncertainty
± 10 %
Measurement Range
0 to 100 W m-2
Measurement Repeatability
Less than 0.5 %
Long-term Drift
Less than 2 % per year
Non-linearity
Less than 1 %
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
180°
Spectral Range
300 to 400 nm (wavelengths where response is greater than 10 % of maximum; see
Spectral Response below)
Directional (Cosine) Response
± 2 % at 45°, ± 5 % at 75°
Temperature Response
Less than 0.1 % per C
Operating Environment
-30 to 85 C; 0 to 100 % relative humidity
Dimension
30.5 mm diameter, 37 mm height
Mass (5 m of cable)
140 g
Cable
5 m of shielded, twisted-pair wire; TPR jacket (high water resistance, high UV stability,
flexibility in cold conditions); pigtail lead wires; stainless steel (316), M8 connector

Cosine Response
Cosine Response Graph
Directional, or cosine, response is
defined as the measurement error at
a specific angle of radiation incidence.
Directional error for Apogee SU-200
series UV-A sensors is approximately ±
2 % and ± 5 % at solar zenith angles of
45° and 75°, respectively.
Mean cosine response of four
Apogee UV-A sensors. Cosine
response was calculated as the
relative difference of UV-A
sensors from the mean of
replicate reference UV-A sensors
deployed outdoors. These data
are the average of the AM and
PM response.

Spectral Response
Spectral response estimate
of Apogee SU-200 UV-A
sensors. Spectral response
was modeled from
sensitivity of the
photodetector and
transmittance of the
diffuser.

DEPLOYMENT AND INSTALLATION
Mount the sensor to a solid surface with the nylon mounting screw provided. To accurately measure UV-A incident
on a horizontal surface, the sensor must be level. An Apogee Instruments model AL-100 Leveling Plate is
recommended to level the sensor when used on a flat surface or being mounted to surfaces such as wood. To
facilitate mounting on a mast or pipe, the Apogee Instruments model AL-120 Solar Mounting Bracket with Leveling
Plate is recommended.
To minimize azimuth error, the sensor should be mounted with the cable pointing toward true north in the
northern hemisphere or true south in the southern hemisphere. Azimuth error is typically less than 1 %, but it is
easy to minimize by proper cable orientation.
In addition to orienting the cable to point toward the nearest pole, the sensor should also be mounted such that
obstructions (e.g., weather station tripod/tower or other instrumentation) do not shade the sensor. Once
mounted, the black cap should be removed from the sensor. The black cap can be used as a protective covering
for the sensor when it is not in use.
Nylon Screw: 10-32x3/8
Model AL-100
Nylon Screw: 10-32x3/8
Model AL-120