LI-COR LI-250A User manual

LI-250A Light Meter
Instruction Manual

LI-250A Light Meter
Instruction Manual
LI-COR Distributor Network:
www.licor.com/env/distributors
LI-COR Biosciences
4647 Superior Street
Lincoln, Nebraska 68504
Phone: [phone]
Toll free: 800-447-3576 (U.S. and Canada)
[e-mail]
Regional Offices
LI-COR Biosciences GmbH
Siemensstraße 25A
61352 Bad Homburg
Germany
Phone: [phone]
[e-mail]
LI-COR Biosciences UK Ltd.
St. John’s Innovation Centre
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Cambridge
CB4 0WS
United Kingdom
Phone: [phone]
envsales[email protected]om

Notice
This manual contains operation and maintenance inform-
ation for the LI-250A Light Meter. Read the operating
instructions before using the LI-250A.
The information contained in this document is subject to
change without notice.
LI-COR MAKES NO WARRANTY OF ANY KIND WITH
REGARD TO THIS MATERIAL, INCLUDING, BUT NOT
LIMITED TO THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE. LI-COR shall not be liable for
errors contained herein or for incidental or consequential
damages in connection with the furnishing, performance,
or use of this material.
This document contains proprietary information which is
protected by copyright. All rights are reserved. No part of
this document may be photocopied, reproduced, or trans-
lated to another language without prior written consent of
LI-COR, Inc.
Copyright © 2004-2019, LI-COR, Inc. All rights reserved.
Document number: 984-07507
1st Printing - March 2004
Updated: Wednesday, July 24, 2019
ii

Contents
Section 1. Operation summary
Configuration mode vs. measurement mode 1
Making measurements 2
Power requirements 4
Section 2. Overview of compatible sensors
Overview of radiation sensor calibration 5
Understanding the certificate of calibration 6
Compatible sensors and accessories 9
Appendix A. Specifications
Range and Resolution 13
Quantum Sensors 13
Pyranometer 13
Photometric Sensor 13
Unit Conversions 14
Appendix B. Warranty
iii

Section 1.
1
Operation summary
The LI-250A Light Meter displays measurements from
LI-COR radiation sensors, including the LI-190R,
LI-191R, LI-192SA, LI-193SA, LI-200R, and LI-210R. It is
compatible with all LI-CORlight sensors that have a BNC
connector. The LI-250A provides high-resolution reading
and conversion of microamp signals from the attached
light sensor into suitable light measurement units. The
LI-250A does not have a specific calibration; calibrations
are associated with the attached light sensor.
Configuration mode vs. measurement mode
The LI-250A has two modes of operation: Configuration
Mode, where you enter calibration multipliers for light
sensors, and Measurement Mode, where the LI-250A makes
measurements. Press the Cal key to switch between modes.
Most of the keys on the 5-button keypad have two func-
tions. The active function depends on whether the
LI-250A is in measurement mode or configuration mode.
In measurement mode, the keys perform the upper func-
tion on each button (in green); in configuration mode,
the keys perform the lower function (in white).

Making measurements
Making measurements
1Attach the desired sensor.
2Power on the meter.
Press and hold the ON key for 2 seconds, and then
release. You will be in measurement mode.
3Press CAL to enter configuration mode.
4Press UNITS until the label on the display matches
the sensor type.
lFor Quantum Sensors, select µmol (actual units are
µmol s-1 m-2)
lFor a Pyranometer, select W m-2 (actual units are
Watts m-2)
lFor a Photometric Sensor, select Lux or Klux (actual
units are Lux or Kilolux)
Readings will be incorrect if the selected units do not
match the sensor that is connected to the meter.
5Press the up or down (▲,▼) key to change the
displayed multiplier until it matches the multiplier
for your sensor.
Press and hold the arrow key to scroll rapidly. The mul-
tiplier is on the calibration sheet under For use with
LI-COR handheld meters and loggers.
6Press CAL again to store the displayed multiplier.
The LI-250A is ready for measurements.
2

Making measurements
If you want to store a second calibration multiplier (either
for a second sensor or the In Water and In Air multipliers
for the LI-192 and LI-193 Underwater Quantum Sensors)
press CAL, then press MULT SELECT to switch to the second
multiplier. Press the arrow key to change the value of the
multiplier, and then press CAL to save it. The multiplier in
effect is the one displayed when you press CAL to exit con-
figuration mode.
Note: Pressing MULT SELECT before pressing CAL dis-
cards any changes you have made to the multiplier cur-
rently shown on the display.
Pressing CAL when in measurement mode will display the
multiplier in current use. The multiplier displayed when
CAL is pressed again will be stored as the active multiplier,
whether you have changed it or not.
While in measurement mode, press HOLD to retain the cur-
rent reading on the display. Press HOLD again to restore
live readings. Press AVG to begin a 15 second average,
which will be displayed until you press the HOLD key to
resume measurements. Press and release the OFF button to
power off the LI-250A. It will automatically shut off after
25 minutes of inactivity in measurement mode.
Caution: The LI-250A is weather resistant. However,
protect the meter from immersion or prolonged contact
with water, especially in marine environments. Water
damage is not covered under the warranty.
3

Power requirements
Power requirements
Power is supplied by one 9-volt battery. Battery life is in
excess of 150 hours. A LO BAT message is displayed when
there is less than 20 hours of battery life remaining. The
battery should be replaced immediately after the LO BAT
message is displayed to ensure reliable operation.
The battery compartment is accessed through a screw-
retained panel on the back of the instrument case.
Remove the battery by lifting on the end of the battery
with the terminals. Insert the new battery by pushing
straight down on the battery; do not try to insert at an
angle. Instruments are fitted with a snap-on connector;
simply align the male and female contacts and snap onto
the battery.
Although typical battery life is more than 150 hours of
continuous operation, it is dependent upon the storage
temperature. Do not store the LI-250A at high tem-
peratures.
In some instances, the internal storage is not retained
when the batteries are removed or when the batteries
become discharged. If the LI-250A is reading 0.0 after
replacing the batteries, check the multipliers stored in the
instrument and verify that they are correct for each sensor.
Re-enter them if necessary.
4

Section 2.
5
Overview of compatible sensors
The LI-250A is compatible with all LI-COR radiation
sensors that have a BNC connector (e.g., LI-200R-BNC or
older LI-200SA sensors). It is important that the LI-250A
be properly configured for the specific sensor used. A
quantum sensor measures photosynthetically active radi-
ation (µmol s-1 m-2 of PAR), a pyranometer measures solar
radiation (W m-2), and a photometric sensor measures illu-
minance (lux). It is not possible for a pyranometer to read
out in units of lux. If you want the LI-250A to display
units of lux, you must use the photometric sensor.
Recalibration of all LI-COR radiation sensors is recom-
mended every two years. The LI-250A does not need to be
recalibrated.
Overview of radiation sensor calibration
All LI-COR radiation sensors produce a current pro-
portional to the radiation intensity. During factory cal-
ibration, sensor output (in microamps) is measured while
the sensor is exposed to a standard lamp of known intens-
ity. The sensor output at this intensity has general units of
microamps per radiation unit and is called the Calibration

Understanding the certificate of calibration
Constant. Each sensor has a slightly different output at a
given radiation intensity and will therefore have a unique
Calibration Constant. The LI-250A measures the current out-
put of the sensor (microamps) and converts the measured
current to units of radiation.
Understanding the certificate of calibration
The Certificate of Calibration (provided with each light
sensor, not the LI-250A) includes the model and serial
number of the sensor, the date of manufacture, the date
of the most recent calibration, and calibration factors that
are suitable for a variety of applications. Calibration cer-
tificates are available from licor.com/env/support.
The Calibration Constant is the relationship between a
microamp of sensor current output and photons of radi-
ation. The value is labeled Output on the calibration sheet.
The value labeled For use with LI-COR handheld meters and
loggers: is the negative reciprocal of the calibration con-
stant (Multiplier = -1 / Calibration Constant). This is the
value you will enter in the LI-250A.
Since the Calibration Constant is unique for each sensor,
it must be entered into the LI-250A each time the sensor is
changed or recalibrated. For the LI-192SA and LI-193SA
Underwater Quantum Sensors, there are two calibration
multipliers (see Figure 2 on page8); one for "in air" oper-
ation and one for "in water" operation. Use the multiplier
that is appropriate for your application.
6

Understanding the certificate of calibration
Figure 1. For terrestrial radiation sensors (LI-190R, LI-191R,
LI-200R, and LI-210R), the value required by the LI-250A is
labeled as For use with LI-COR handheld meters and loggers:.
The units given will depend on the sensor in use.
7

Understanding the certificate of calibration
Figure 2. For underwater quantum sensors (LI-192SA and LI-
193SA), the values required by the LI-250A are labeled as
For use with LI-COR handheld meters and loggers:. Two values
are given: one for use in air, and another for use in water.
Older radiation sensors
For type ‘SA’ sensors manufactured between September
1985 and March 2015, the calibration multiplier is
attached to the sensor cable and provided on the cer-
tificate. The time coefficient (tcoff) is used to convert integ-
rated data to the proper units when using the LI-1000
Datalogger to log data with certain sensors. This value can
be ignored when using the LI-250A.
8

Compatible sensors and accessories
Older type 'SB' radiation sensors and new sensors
equipped with the millivolt adapter (denoted ‘-SMV’) are
also compatible if the Calconnector (Calibration con-
nector) is detached from the BNC connector.
Older type 'SZ' radiation sensors are not compatible with
the LI-250A unless they are fitted with a BNC connector.
Contact LI-COR for more information.
Calibration certificates for all sensors are available from
licor.com/env/support.
Compatible sensors and accessories
The following accessories and sensors are available for the
LI-250A. Contact LI-COR for current information.
lLI-190R-BNC Quantum Sensor: Measures Pho-
tosynthetically Active Radiation (PAR) in natural sun-
light, under plant canopies, and in growth chambers
and greenhouses.
lLI-191R Line Quantum Sensor: Measures average
PPFD over its one-meter length for plant canopy
PPFD profile studies.
lLI-192SA Underwater Quantum Sensor1:Measures
Photosynthetic Photon Flux Density (PPFD) in air or
under water incident on a flat plane.
9

Compatible sensors and accessories
lLI-193SA Spherical Quantum Sensor:1Measures
photon flux from all directions under water. This meas-
urement is called Photosynthetic Photon Flux Fluence
Rate (PPFFR).
lLI-200R-BNC Pyranometer: Measures global solar
radiation (sun plus sky) and provides a typical accuracy
of ±5% under unobstructed daylight conditions.
lLI-210R-BNC Photometric Sensor: Measures visible
radiation and has a spectral response equal to that for
the average human eye. Readout of illuminance (in
lux) is used for lighting studies or architectural mod-
eling.
l250-01 Carrying Case: A padded case for the LI-250A
and terrestrial type radiation sensors. Size: 20.3 cm L ×
10.2 cm W × 9 cm D (8" × 4" × 3.5"). Weight: 98 g
(0.216 lbs).
l2003S Mounting and Leveling Fixture: The 2003S is
for use with all LI-COR terrestrial type sensors.
l2222SB Extension Cable: For use with all LI-COR ter-
restrial type sensors. Available in 15.2 m (50 ft), 30.4 m
(100 ft), or custom lengths to 304 m (1000 ft).
lReplacement Battery: 9 Volt Battery. The LI-250A
requires a battery for operation.
1Requires 2222UWB cable.
10

Appendix A.
11
Specifications
Accuracy: 25 °C: Typically ± 0.4% of reading [± 3 counts
on the least significant digit displayed (all ranges)].
0-55 °C: Typically ± 0.6% of reading [± 3 counts on the
least significant digit displayed (all ranges)].
Range Selection: Autoranging (3 ranges).
Sensor Calibration: Calibration multipliers for two
sensors are stored in memory. Calibration multipliers
are entered from the keypad.
Sensor Averaging: Sensor output is averaged for 15
seconds when AVG key is pressed in Measurement
mode. Averages are displayed in HOLD mode to
retain the average on the display.
Linearity: ± 0.05%.
Operating Conditions: 0 to 55 °C, 0 to 95% RH (non-
condensing).
Storage Conditions: -55 to 60 °C, 0 to 95% RH (non-
condensing).
Display: 4 1/2-digit custom LCD display. Updated every
0.5 seconds.
Keypad: Sealed, 5-key tactile response keypad.
Battery Life: 150 hours typical with continuous oper-
ation. Automatic shutoff after 25 minutes of inactiv-
ity in measurement mode.

Appendix A. Specifications
Power Requirement: One 9 V alkaline battery or equi-
valent.
Low Battery Detection: Low battery indicator displayed
with approximately 20 hours battery life remaining.
Size: 15 cm L × 8.2 cm W × 3.3 cm D (5.9" × 3.2" × 1.3").
Weight: 0.26 kg (0.57 lbs).
Compatible Sensors: Any LI-COR sensor with BNC
connector; Quantum, Pyranometer, or Photometric.
Warranty: 1-year parts and labor.
12

Range and Resolution
Range and Resolution
Quantum Sensors
Range Resolution
0-199 µmol s-1 m-2 0.01 µmol s-1 m-2
0-1999 µmol s-1 m-2 0.1 µmol s-1 m-2
0-19999 µmol s-1 m-2 1 µmol s-1 m-2
Pyranometer
Range Resolution
0-19 W m-2 0.001 W m-2
0-199 W m-2 0.01 W m-2
0-1999 W m-2 0.1 W m-2
Photometric Sensor
Range Resolution
0-1999 lux 0.1 lux
0-19999 lux 1 lux
0-199 klux 0.01 klux
0-199 fc 0.01 fc
0-1999 fc 0.1 fc
0-19999 fc 1 fc
13

Unit Conversions
Unit Conversions
Quantum Sensors
1.0 µmol s-1 m-2
= 1 µE s-1 m-2
= 6.022 × 1017 photons s-1 m-2
= 6.022 × 1017 quanta s-1 m-2
= 6.022 × 1013 quanta s-1 cm-2
Pyranometer
1 W m-2
= 1.433 × 10-3 cal cm-2 min-1
= 1.433 × 10-3 langley min-1
= 0.100 mW cm-2
= 100 µW cm-2
= 1.0 J s-1 m-2
= 1000 erg s-1 cm-2
= 0.317 BTU ft-2 h-1
= 5.283 × 10-3 BTU ft-2 min-1
Photometric Sensor
1 lux
= 1 lm m-2
= 0.0929 lm ft-2
= 0.0929 fc
= 0.001 klux
14

Appendix B.
15
Warranty
Each LI-COR, Inc. instrument is warranted by LI-COR,
Inc. to be free from defects in material and workmanship;
however, LI-COR, Inc.'s sole obligation under this war-
ranty shall be to repair or replace any part of the instru-
ment which LI-COR, Inc.'s examination discloses to have
been defective in material or workmanship without charge
and only under the following conditions, which are:
1The defects are called to the attention of LI-COR,
Inc. in Lincoln, Nebraska, in writing within one
year after the shipping date of the instrument.
2The instrument has not been maintained,
repaired or altered by anyone who was not
approved by LI-COR, Inc.
3The instrument was used in the normal, proper
and ordinary manner and has not been abused,
altered, misused, neglected, involved in an acci-
dent or damaged by act of God or other casualty.
4The purchaser, whether it is a DISTRIBUTOR or
direct customer of LI-COR or a DISTRIBUTOR'S
customer, packs and ships or delivers the