Model 401025 Digital Light Meter

User's Manual
Model 401025
Digital Light Meter
Introduction
Congratulations on your purchase of Extech’s Digital Light Meter. This professional meter, with proper
care, will provide years of safe reliable service.
Meter Description
1.
LCD Display
2.
Data Hold Switch
3.
Power Off/Range Switch
4.
Analog Output Terminal
5.
Battery Compartment (rear)
6.
LUX/Fc Switch & Response Switch
7.
Light Sensor
8.
Zero adjust
1
2
3
6
4
7
8
5
Operation
1.
2.
3.
4.
5.
Select Units (Lux or Ft-candle) and Response Time (Fast or Slow) on the slide switch.
Typical selection is Slow and Fc using the gray lettering.
Select the maximum range on the "Range Switch"
Hold the "Light Sensor" so that the sensor faces the light source to be measured.
The Display will indicate measured values. Use a range display multiplier if on the Lux
20,000 and 50,000 ranges or on the Fc 5000 range.
To "hold" a measurement, slide the "Data Hold Switch" to the "hold" position. The reading
will "freeze" in the display until the "Data Hold Switch" is released.
Note 1: An Over Range indication is a display of "I
". If this occurs, switch to a higher range.
Note 2: For measurements made on the Fc 5000 range, the displayed reading must be multiplied
by 10.
Note 3: For measurements made on the Lux 20000 or 50000 range, the displayed reading must
be multiplied by 10 and 100 respectively.
Note 4: The meter will indicate values above the maximum ranges. The accuracy of these
measurements is unknown.
Range Display Multipliers
Range
Units
Multiplier
200
Fc
Direct reading
2000
Fc & Lux
Direct reading
5000
Fc
Reading x10
20,000
Lux
Reading x10
50,000
Lux
Reading x100
Lux
Example: If a measurement on the 5000 Fc range displays 350, then the actual measured value
is; 350 X 10 = 3500 Fc.
2
401025-EU-EN-V2.3 7/12
Selecting a Measurement Range
The meter has three measurement ranges (0-200, 0-2000, and 0-5000 Fc) and (0-2000, 0-20000, and
0-50000) Lux). The proper range selection will produce the most accurate reading. Always select the
range that produces the maximum number of digits without exceeding the maximum count for that
particular range. For example, a reading of 1456 Fc should be read on the 0 - 2000 range, not the 05000 range.
Zero procedure
The meter zero (display with no light input) may change with time. Occasional checking and
adjustment may be required.
1. Completely cover the sensor to block out any light.
2. Set the range switch to the lowest Lux or Fc range
3. Using a small screwdriver, adjust the “Zero” control for a zero display. The last digit may
change slightly. This is normal and does not affect the accuracy of the meter.
Analog Output
The analog output jacks on the front panel produce a 0.1mV DC per digit signal that can be used for
recording or datalogging purposes.
Lighting Type Correction Factors
O
The 401025 light meter is calibrated under a precise "Standard tungsten light source of 2856 K". If the
meter is to be used under a different type of light the correction factor of from the table below should
be applied to the readings obtained.
Mercury Lamp
Fluorescent Lamp
Daylight
Sodium
Metal Halide
x1.14
X0.92 to 1.12
x1.00
x1.22
x1.00
Replacing the Battery
When the left corner of the LCD display shows "LO BAT", it indicates the battery output is below the
design limit and the battery needs to be replaced. However, reliable measurement can still be taken for
another few hours before the tester becomes inaccurate.
1. Open the Battery Cover at the back of tester and remove the battery.
2. Replace with a 9V battery and install the cover.
You, as the end user, are legally bound (EU Battery ordinance) to return all used
batteries, disposal in the household garbage is prohibited! You can hand over your
used batteries / accumulators at collection points in your community or wherever batteries
/ accumulators are sold!
Disposal: Follow the valid legal stipulations in respect of the disposal of the device at the
end of its lifecycle
3
401025-EU-EN-V2.3 7/12
Specifications
General Specifications
Display
Measurement
Ranges
Sensor
Zero Adj.
Sampling Time
Response Time
Over input indication
Analog Output
Operating Temperature
Operating Humidity
Power Supply
Power Current
Weight
Dimension
Optional Accessories
Range Specifications
Lux
Range
2,000 Lux
20,000 Lux
50,000 Lux
Foot-candle (Fc)
Range
200 Fc
2,000 Fc
5,000 Fc
13 mm (0.5") LCD (Liquid Crystal Display).
Lux, Ft-candle (Fc).
Lux: 0 to 50,000 Lux, 3 ranges. Foot-candle: 0-5,000 Fc, 3
ranges.
Exclusive photo diode & color correction filter, spectrum
designed to meet C. I. E.
Manual adjustment.
Approx. 0.4 sec.
Fast: 0.25s; Slow: 1s
Indication of "1 "
0.1 mV/1 digit, max. output :200mV.
O
O
O
O
0 C to 50 C (32 F to 122 F)
Less than 80% RH.
006P DC 9V battery
Approx. 2 mA DC
220 g / 0.52 LB
Main instrument: 163x70x30mm (6.4x2.8x1.2 inch).
Sensor Probe: 85x55x12 mm (3.2x2.2x0.5 inch).
Vinyl pouch carrying case, 409996
In-range Display
0-1,999 Lux
2,000-19,990 Lux
20,000-50,000 Lux
Resolution
1 Lux
10 Lux
100 Lux
Accuracy (FS)
± (5% + 2digits)
± (5 % + 2digits)
±- (5 % + 2digits)
In-range Display
0-199.9 Fc
200-1,999 Fc
2,000-5,000 Fc
Resolution
0.1 Fc
1 Fc
10 Fc
Accuracy (FS)
± (5% + 2digits)
± (5% + 2digits)
± (5% + 2digits)
Frequency Spectrum
1
0.8
0.6
0.4
0.2
0
300
400
500
600
700
800
Wavelength (nm)
4
401025-EU-EN-V2.3 7/12
Appendix A: Typical Light Levels
Lux
Foot
Candles
20-75
2-7
75-150
7-15
Factories
Emergency Stairs,
Warehouse
Exit/Entrance Passages
150-300
15-30
300-750
30-75
750-1,500 75-150
1,5003,000
150-300
75-100
100-200
7-10
10-20
200-750
20-75
750-1,500 75-150
1,500150-2000
2,000
75-150
150-200
200-300
7-15
15-20
20-30
300-500 30-50
500-750 50-75
750-1,500 75-150
1,5003,000
150-300
Lux
Foot
Candles
100-150
10-15
150-200
15-20
Packing Work
200-300
20-30
Visual Work: Production
Line
Typesetting: Inspection
Work
Electronic Assembly,
Drafting
Office
Indoor Emergency Stairs
Corridor Stairs
300-500
30-50
Recreational
Activities
Drawing Room,
Table
Makeup
500-1,500
50-150
Reading, Study
1,0002,000
100-200
Sewing
75-150
150-300
7-15
15-30
Conference, Reception
Room
Clerical Work
Typing, Drafting
300-750
30-75
750-1,500
75-150
30-75
75-100
100-150
3-7
7-10
10-15
150-200
200-750
750-1,500
15-20
20-75
75-150
Hospital
Emergency Stairs
Stairs
Sick Room,
Warehouse
Waiting Room
Medical Exam Room
Operating Room
5,00010,000
500-1000
Eye Inspection
Store
Indoors
Corridor/Stairs
Reception
Display Stand
Elevator
Show Window, Packing
Table
Storefront, Show Window
Home
Washing
Restaurant
Corridor Stairs
Entrance, Wash
Room
Cooking/Dining
Room
Show Window
Appendix B - Common Terms and Conversion Factors
Illuminance (Visible Flux Density)
1 lm/m2 =
1 lux (lx)
10-4 lm/cm2
10-4 phot (ph)
9.290 x 10-2 lm/ft2
Luminance (Visible Flux Density per Solid Angle)
1 lm/m2/sr =
Luminous Intensity (Visible Flux per Solid Angle)
Luminous Flux ( Visible Flux)
1 lm/sr =
1 lumen (lm) =
9.290 x 10-2 foot-candles
1 candela/m2
1 candella
1.464 x 10-3 watts @ 555 nm
Copyright © 2012 Extech Instruments Corporation (a FLIR company)
All rights reserved including the right of reproduction in whole or in part in any form.
www.extech.com
5
401025-EU-EN-V2.3 7/12