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20. CHANGING THE SETTINGS
126
I
"ppm" tab
•
[0ppm]
: Atmospheric correction factor returns to 0 and temperature and air pressure are set to
the factory settings.
• Atmospheric correction factor is calculated and set using the entered values of the temperature
and air pressure. Atmospheric correction factor can also be entered directly.
• When the settings here are different between basic mode and program mode, program mode
settings are prior for use.
Items set, options, and input range (*: Factory setting)
Temperature
: -30 to 60°C (15*), -22 to +140°F (59*)
Pressure
: 500 to 1400hPa (1013*), 375 to 1050mmHg (760*),
14.8 to 41.3 (inchHg) (29.9*)
Humidity
: 0 to 100% (50*)
ppm (Atmospheric correction factor)
: -499 to 499 (0*)
• The "Humidity" item is displayed only when the "ppm setting" in "Obs. condition" is set to
"+Humidity".
• When 0.1mm is selected in "Dist.reso", values can be input to the first decimal place.
&
Atmospheric correction factor
The velocity of the light beam used for measurement varies according atmospheric conditions
such as temperature and air pressure. Set the atmospheric correction factor when you wish to
take this influence into account when measuring.
• The instrument is designed so that the correction factor is 0 ppm at an air pressure of 1013
hPa, a temperature of 15°C, and a humidity of 50%.
• By inputting the temperature, air pressure values and humidity, the atmospheric correction
value is calculated using the following formula and set into the memory.
t: Air temperature (
°
C)
p: Pressure (hPa)
e: Water vapor pressure (hPa)
h: Relative humidity (%)
E : Saturated water vapor pressure
282.324
0.294362 p
×
1 0.003661 t
×
+
------------------------------------------
–
0.04127 e
×
1 0.003661 t
×
+
------------------------------------------
+
Atmospheric Correction Factor (ppm) =