Flow Tracker Series 1000/2000
Reference Manual
27
5
When a satisfactory zero is obtained, move the end of the
suction probe to the point of the suspected leak. Allow a few
seconds for the sample to reach the sensors.
Leak mode parameters
The Leak detector mode screen (shown in
) displays the
following parameters:
Leak rate
The leak rate for the selected gas is inferred from
the conductivity of the gas being sampled, the known
conductivity of the selected gas, and the known constant flow
rate provided by the sampling pump. This parameter is located
in the upper left corner of the display below the dynamic label
“Rate”. The engineering unit associated with this parameter is
cubic centimeters per second (cc/sec).
Thermal conductivity
The thermal conductivity of a gas is a
measure of its ability to conduct heat. The absolute thermal
conductivity of the gas presently being sampled is located in the
upper middle of the display under the dynamic label “Cond.”
The engineering units associated with the thermal conductivity
shown are the value x 10
-6
((cal/(sec)(cm
2
)(°C/cm)). Because of
the excessive length of the units, they are not shown on the
display.
Relative conductivity indicator
The relative conductivity
indicator is a dimensionless value reflecting the raw sensor
measurement of the difference in temperature between the
heated and unheated sensors. This parameter is located in the
lower left corner of the display above the dynamic label “Rel.” It
can be signed plus or minus with zero being the state at which
the device was last zeroed, which is nominally in ambient air.
This value can be roughly interpreted as:
N O T E
The thermal conductivity of air is given as 62.2 x 10
-6
((cal/(sec)(cm
2
)(°C/cm)) in the CRC Handbook of Chemistry and
Physics [1].
