5. Press the “ “ and the “ “ at the same time to turn the
laser targeting feature ON or OFF.
6. When the laser targeting feature is on, and the “ “
push-button is pressed, you will see the “ “ symbol on the left
side of the LCD screen.
Auto Power Off Time Setting
The auto power off function is factory set to turn the DTH51 off in 5
minutes (300 seconds). To override the auto power off function , press
and hold down the “ “ push-button as you press the power
“ “ push-button. When an “
” appears (Non sleep mode) in the
top line of the LCD, release both buttons and you will resume normal
function with the ability to monitor readings over long periods without
the instrument shutting itself off.
Auto power off disabled at turn-on
After turning the instrument on, you can adjust the amount of time
before the auto power off function shuts off the DTH51 by briefly
pressing the “ “ push-button. The time that the instrument will
remain on, shown in seconds from 5 to 600, will be displayed in the
top line of the LCD.
Auto power off timer
1. Press the “ “ push-button to increase on-time.
2. Press the “ “ push-button to decrease on-time.
3. Press the “ “ push-button to lock in the new timer setting
and advance to the emissivity adjustment option, or press it twice
to return to the measurement mode.
Adjusting Emissivity
Emissivity is an adjustment that you can use to calibrate your DTH51
when measuring different types of surfaces.
The chart (Fig 2) provides the specific values of different surfaces that
you can use when setting the adjustable emissivity values (between .3
to .99). A “.95” emissivity value is most connonly used.
After turning the instrument on, you can enter the emissivity adjustment
mode by briefly pressing the “ “ push-button twice.
DTH51-MAN
P. 3
The emissivity value that your DTH51 will use when taking infrared
measurements will be shown on the top line of the LCD.
Emissivity adjustment screen
1. Press the “ “ push-button to increase emissivity.
2. Press the “ “ push-button to decrease emissivity.
3. Press the “ “ push-button to lock in your new e m i s s i v i ty
setting and cycle back to the measurement mode.
Emissivity Values
Surface
Emissivity
Iron and Steel
Cast iron (polished)
0.2
Cast iron (turned at 100˚C)
0.45
Cast iron (turned at 1000˚C)
0.6 to 0.7
Steel (ground sheet)
0.6
Mild steel
0.3 yo 0.5
Steel plate (oxidized)
0.9
Iron plate (rusted)
0.7 to 0.85
Cast iron (rough) rusted
0.95
Rough ingot iron
0.9
Molten cast iron
0.3
Molten mild steel
0.3 to 0.4
Stainless steel (polished)
0.1
Stainless steel (various)
0.2 to 0.6
Aluminum
Polished aluminum
0.1*
Aluminum (heavily oxidized)
0.25
Aluminum oxide at 260˚C
0.6
Aluminum oxide at 800˚C
0.3
Aluminum alloys, various
0.1 to 0.25
Brass
Brass (polished)
0.1*
Brass (roughened surface)
0.2
Brass (oxidized)
0.6
Copper
Copper (polished)
0.1*
Copper (oxidized at 25˚C)
0.8
Molten copper
0.15
Lead
Lead (pure)
0.1*
Lead (oxidized at 25˚C)
0.3
Lead (oxidized, heated to 200˚C)
0.6
