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: +1-402-467-3576

Toll free: 800-447-3576 (U.S. and Canada)

envsales@licor.com

Regional Offices

LI-COR Biosciences GmbH

Siemensstraße 25A

61352 Bad Homburg

Germany

Phone: +49 (0) 6172 17 17 771

envsales-gmbh@licor.com

LI-COR Biosciences UK Ltd.

St. John’s Innovation Centre

Cowley Road

Cambridge

CB4 0WS

United Kingdom

Phone: +44 (0) 1223 422102

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.

Document number: 984-07507

1st Printing - March 2004

Updated: Wednesday, July 24, 2019

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.

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

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.

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.

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.

Section 2.

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

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