Extech Instruments 42540a User manual

User’s Manual

High Temperature InfraRed Thermometer

with Laser Pointer

MODEL 42540A

42540

Model 42540A V2.1 January 20062

Introduction

Congratulations on your purchase of the Model 42540A IR Thermometer. The 42540A is

capable of non-contact (infrared) temperature measurements at the touch of a button. The

built-in laser pointer increases target accuracy while the backlit LCD and handy push-

buttons combine for convenient, ergonomic operation. This meter is shipped fully tested

and calibrated and, with proper use, will provide years of reliable service.

Warranty

EXTECH INSTRUMENTS CORPORATION warrants this instrument to be free of defects in parts and

workmanship for three (3) years from date of shipment (a six month limited warranty applies on sensors and

cables). If it should become necessary to return the instrument for service during or beyond the warranty

period, contact the Customer Service Department at (781) 890-7440 ext. 210 for authorization or visit our

website at www.extech.com (click on ‘Contact Extech’ and go to ‘Service Department’ to request an RA

number). A Return Authorization (RA) number must be issued before any product is returned to Extech. The

sender is responsible for shipping charges, freight, insurance and proper packaging to prevent damage in

transit. This warranty does not apply to defects resulting from action of the user such as misuse, improper

wiring, operation outside of specification, improper maintenance or repair, or unauthorized modification. Extech

specifically disclaims any implied warranties or merchantability or fitness for a specific purpose and will not be

liable for any direct, indirect, incidental or consequential damages. Extech's total liability is limited to repair or

replacement of the product. The warranty set forth above is inclusive and no other warranty, whether written or

oral, is expressed or implied.

Calibration and Repair Services

Extech offers repair and calibration services for the products we sell. Extech also

provides NIST certification for most products. Call the Customer Service Department for

information on calibration services available for this product. Extech recommends that

annual calibrations be performed to verify meter performance and accuracy.

Safety

•Use extreme caution when the laser pointer beam is on

•Do not point the beam toward anyone's eye or allow

the beam to strike the eye from a reflective surface

•Do not use the laser near explosive gases or in other

potentially explosive areas

Model 42540A V2.1 January 20063

Meter Description

1. Laser pointer beam

2. IR Sensor

3. Measurement Trigger

4. Battery and Switch Compartment

5. LCD Display

6. Push-buttons

7. Handle Grip

8. Temperature Units (ºC/ºF) Switch

9. Test Lock ON/OFF Switch

10. Alarm ON/OFF Switch

Note: There is a tripod mount on the bottom of the handle

42540

Model 42540A V2.1 January 20064

Operating Instructions

Basic IR Measurements

1. Hold the meter by its handle and point it toward the surface to be measured.

2. Pull and hold the trigger to turn the meter on and begin testing. The temperature

reading, the flashing ‘SCAN’ icon, the emissivity, and the unit of measure will appear.

Note: Replace the 9V battery if the display does not switch on.

3. Release the Trigger and the reading will hold for approximately 7 seconds (HOLD will

appear on the LCD) after which the meter will automatically shut off. The only

exception to this is if the TEST LOCK switch is set to ON.

Note: Select the temperature units (ºF/ºC) using the top switch inside the battery

compartment

Backlight/Laser Pointer

1. While pulling the Trigger, push the backlight/laser button once to turn on the

backlight.

2. Press it again to turn on the laser pointer. When the laser is ON the laser icon will

appear in the LCD.

3. Press the laser button to turn the backlight off.

4. Pressing it again turns the laser off.

Note: Backlight and Laser settings will be retained after the meter powers down.

Over-range Indication

If the temperature measurement exceeds the specified temperature range, the

thermometer will display dashes in place of a temperature reading.

Model 42540A V2.1 January 20065

The MODE button options

The MODE button is used to access the programming functions of the instrument. The

selected function is displayed on the bottom line of the LCD. Each parameter is listed

below with an explanation for its use. Press the MODE button to step from one parameter

to the next.

EMS (Emissivity Value)

To change the emissivity value, use the UP and DOWN arrows (the range is 0.10

to 1.00). The current emissivity setting is always shown at the top of the LCD

display. A setting of 0.95 covers about 90% of all applications and, when in doubt,

should be set as such. Emissivity is discussed in a dedicated section of this

manual.

MAX (Maximum function)

In the MAX mode, only the highest reading encountered in the current

measurement session is displayed

MIN (Minimum function)

In the MIN mode, only the lowest reading is displayed

DIF (Max minus Min value)

In the DIF mode, the MAX less the MIN is displayed.

AVG (Average value)

In the AVG mode, all of the readings in the current measurement session are

averaged and the value is displayed.

HAL (High Alarm setting)

The temperature that, when exceeded, causes the audible/visual alarm to trip.

LAL (Low Alarm setting)

The temperature that, when exceeded high to low, causes the audible/visual

alarm to trip.

High and Low Alarm Feature

The Model 42540a has an alarm feature whereas a High Alarm setting and a Low Alarm

setting can be programmed by the user. When either Alarm point is reached the meter will

alert the user via an audible beep and LCD display icon. Follow the steps below:

1. Press the MODE button until the HAL (High Alarm) parameter is displayed. Use the

UP and DOWN arrow keys to set the desired High Alarm temperature setting.

2. Press the MODE button until the LAL (Low Alarm) parameter is displayed. Use the

UP and DOWN arrow keys to set the desired Low Alarm temperature setting.

3. When an alarm limit is reached, the audible alarm will sound and the display icon

HIGH or LOW will appear on the LCD.

4. Note that if the bottom switch (located in the battery compartment) is set to OFF, the

audible alarm will be disabled.

Model 42540A V2.1 January 20066

Battery Replacement

When the battery symbol appears empty or close to empty, replace the

meter’s 9V battery. The battery compartment is located behind the panel

that surrounds the meter’s trigger. The panel can be pried open near the

trigger and folded down as shown in the diagram. Replace the 9V battery

and close the battery compartment cover.

IR Measurement Notes

1. The object under test should be larger than the spot (target) size calculated by the field

of view diagram (printed on the side of the meter and in this guide).

2. Before measuring, be sure to clean surfaces that are covered with frost, oil, grime, etc.

3. If an object's surface is highly reflective, apply masking tape or flat black paint to the

surface before measuring. Allow time for the paint or tape to adjust to the temperature

of the surface it is covering.

4. Measurements through transparent surfaces such as glass may not be accurate.

5. Steam, dust, smoke, etc. can obscure measurements.

6. The meter automatically compensates for deviations in ambient temperature. However,

it can take up to 30 minutes for the meter to adjust to extremely wide changes.

7. To find a hot spot, aim the meter outside the area of interest then scan across (in an up

and down motion) until the hot spot is located.

Field of View

The meter’s field of view is 16:1. For example, if the meter is 16 inches from the target

(spot), the diameter of the target must be at least 1 inch. Other distances are shown in the

field of view diagram. Note that measurements should normally be made as close as

possible to the device under test. The meter can measure from moderate distances but the

measurement may be affected by external sources of light. In addition, the spot size may

be so large that it encompasses surface areas not intended to be measured.

Model 42540A V2.1 January 20067

Emissivity and IR Measurement Theory

IR Thermometers measure the surface temperature of an object. The thermometer’s optics

sense emitted, reflected, and transmitted energy. The thermometer’s electronics translate

the information into a temperature reading which is then displayed on the LCD.

The amount of IR energy emitted by an object is proportional to an object's temperature

and its ability to emit energy. This ability is known as emissivity and is based upon the

material of the object and its surface finish. Emissivity values range from 0.1 for a very

reflective object to 1.00 for a flat black finish. For the Model 42540a, the emissivity is

adjustable from 0.1 to 1.00. Most organic materials and painted or oxidized surfaces have

an emissivity factor of 0.95. When in doubt, set the emissivity to 0.95.

Emissivity Factors for Common Materials

Material under test Emissivity Material under test Emissivity

Asphalt 0.90 to 0.98 Cloth (black) 0.98

Concrete 0.94 Skin (human) 0.98

Cement 0.96 Leather 0.75 to 0.80

Sand 0.90 Charcoal (powder) 0.96

Soil 0.92 to 0.96 Lacquer 0.80 to 0.95

Water 0.92 to 0.96 Lacquer (matt) 0.97

Ice 0.96 to 0.98 Rubber (black) 0.94

Snow 0.83 Plastic 0.85 to 0.95

Glass 0.90 to 0.95 Timber 0.90

Ceramic 0.90 to 0.94 Paper 0.70 to 0.94

Marble 0.94 Chromium Oxides 0.81

Plaster 0.80 to 0.90 Copper Oxides 0.78

Mortar 0.89 to 0.91 Iron Oxides 0.78 to 0.82

Brick 0.93 to 0.96 Textiles 0.90

Model 42540A V2.1 January 20068



Support line (781) 890-7440

Technical support: Extension 200; E-mail: support@extech.com

Repair & Returns: Extension 210; E-mail: [email protected]

Product specifications subject to change without notice

For the latest version of this User’s Guide, Software updates, and other

up-to-the-minute product information, visit our website: www.extech.com

Extech Instruments Corporation, 285 Bear Hill Rd., Waltham, MA 02451

Specifications

Infrared Thermometer Specifications

Range / Resolution -58 to 1400oF (-50 to 760oC) 0.1oC/F over entire range

Accuracy

(of reading) ± 2% of reading or 4oF (2oC) whichever is greater < 932oF (500oC)

± (2.5% of reading + 5o) > 932oF (500oC)

Note: Accuracy is specified for the following ambient temperature

range: 64 to 82°F (18 to 28°C)

Emissivity Adjustable from 0.1 to 1.00 (0.95 default value)

Field of View D/S = Approx. 16:1 ratio (D = distance, S = spot)

Laser power Less than 1mW

Spectral response 6 to 14 µm (wavelength)

General Specifications

Display 4½ digit backlit LCD display with function indicators

Display rate 1 second approx.

Operating

Temperature 32°F to 122°F (0°C to 50°C)

Operating Humidity Max. 80% RH.

Power Supply 9V battery

Automatic Power Off Approx. 6 seconds after the trigger is released

Safety compliance CE

Weight 10.2 oz. / 290g

Dimensions 3.9 x 2.2 x 9.0” (100 x 56 x 230mm)

Table of contents

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