Teledyne ULTRAFLOW 150, Operation Manual, Page: 21 / 162

SECTION 4.0, Theory of operation
4.1.1.2 Temperature Measurement
By knowing the precise time required for the tone bursts to traverse the gas stream
the speed of sound is calculated. The influence on the speed of sound resulting
from temperature change is well established. Therefore, the gas stream
temperature measurement may be calculated directly from the speed of sound
determination. This measurement will remain accurate so long as the gas
composition is from a single fuel source or remains relatively consistent in terms
of its molecular weight.
If multi-fuel operation is expected, the Ultraflow 150 should be configured using
an external temperature device that may be facilitated using the optional Dual
Analog Input Board.
Consult the Site Specification Data sheet of Appendix A for information on the
configuration of your individual monitor
4.1.2 Flow Volume Measurement
Once the flow velocity ( F
ν
) has been determined it is multiplied by the cross-
sectional area of the stack or duct to determine the actual volumetric flow. The
units may be English or Metric, per hour, minute or second, according to a
software selection.
4.1.3 Wet Basis and Dry Basis Measurements
The Ultraflow 150 gives a wet basis reading only. A wet basis measurement is
one that includes the water vapor component of the effluent in the measurement.
A dry basis measurement is one that removes the water vapor and makes the
measurement on the remaining components of the effluent.
4.1.4 Correction to Standard Temperature and Pressure
Effluent pressure and temperature can vary dramatically from one process to
another. For the sake of uniform reporting most regulatory applications require
the volume and mass flow to be reported in standard pressure and temperature
units. To do this, the monitor’s measurement must be corrected according to the
ideal gas law for the agency specified pressure and temperature. US EPA
standard (reference) conditions are 68
0
F and 29.92 in. Hg for English units and
20
0
C and 101.32 Kpa for metric units. The Ultraflow 150 has the ability to take
inputs from an external pressure transducer and a temperature device. The
monitor’s internal temperature measurement may also be used for correction.
Each correction factor can be turned on or off individually to accommodate
systems that do these functions elsewhere.
4-3