Mesalabs Defender 530, Руководство пользователя, Страница: 28 / 29

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Why am I experiencing a temperature increase in my De-
fender 530?
A temperature rise during initial battery charging, or while charging a fully
discharged battery is normal. To maintain the best possible accuracy Mesa
recommends fully charging your battery before taking measurements. If this is
not possible, we recommend disconnecting your Defender from its AC power
adapter/charger while taking flow measurements – or to run gas through your
Defender for 10 minutes before starting the flow measurement.
Why doesn’t my piston return to the bottom of the cell?
If the piston fails to return to the bottom of the cell after a measurement this
could be caused by:
• A discharged battery not providing enough power to operate the internal
valve properly (Try charging the Defender)
• Bright light shining into the unit resulting in an overload of the internal opti -
cal sensors (Try to operate the unit in a shaded location)
• Moisture or dirt inside the cell (Return the Defender to Mesa for service)
What is dead volume?
Dead volume is the gas volume between a flow generator and the instrument
taking the measurement. Since gas is compressible, this gas can act as a
spring between the flow source and the measurement instrument. For best ac -
curacy, this volume should be kept to a minimum. We recommend keeping the
tubing length between the gas flow generator and your Defender to no more
than 0.5 meters/20 inches in length.
What is the difference between volumetric flow and
standardized flow?
As we know from the ideal gas law, the volume of a gas changes with a
change in temperature or pressure even when the number of molecules which
constitute the mass remains the same.
Volumetric flow rate is the rate at which a volume of a gas travels past a given
location. Volumetric Flow= As Measured Volume of Gas / Time
Standardized (mass) flow rate is expressed as the rate at which the volume
of a gas travels past a given location if the gas is at a specified temperature
and pressure. From the ideal gas law if the temperature and pressure are held
constant, the volume of the gas is proportional to the number of molecules.
Standardized Flow= Volume of Gas (at the standard
temperature and pressure) / Time
10.0
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