H4-EN Calibration P
AGE
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The ambient conditions are used to calculate BTPS correction factor. It is
essential that ambient conditions are measured or encoded correctly for
accurate volume measurement:
• Temperature: in degrees Celsius
• Relative humidity: in % (absolute)
• Barometric pressure: in mmHg
Important information on barometric pressure
The barometric pressure used by the software is the actual barometric
pressure, not barometric pressure corrected at sea level and not relative
humidity. Be careful when using an external weather station because it
always indicates barometric pressure corrected at sea level, depending on
the altitude of the location.
In order to obtain the real barometric pressure, the formula below can be
used:
BP
BP
1
0.0065h
288.15
.
Where:
- BP
corr
is the barometric pressure (in mmHg) corrected at sea level, as
indicated on all external weather stations
- h is the altitude (in meters)
Example: a weather station indicates 760 mmHg at an altitude of 250 meters.
This will correspond to a real barometric pressure of 738 mmHg.
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