APPENDIX A. CALIBRATION EQUATIONS
Because the PQ100 uses a "Through Stream" mass flow sensor, the mass flow is not affected by
pressure and temperature. However, the velocity (flow rate) through a fixed area nozzle will vary
with atmospheric conditions. When work is carried out in an area with conditions other than
Engineering Standard Conditions the "Corrected Flow Rate" is that which is measured on the
calibration device for these new conditions.
The following equations are used to determine the "Corrected Flow Rate" that should be set on
the PQ100 for atmospheric conditions other than "Engineering Standard Conditions" of
20 degrees Celsius (293.18 degrees Kelvin) and 760 millimeters of Mercury. They are provided
for users who do not have access to an IBM PC or Compatible and can not use the "CORRECT"
utility provided on the floppy disk.
These equations and recommendations have been prepared for Investigators with an advanced
understanding of atmospheric sampling procedures. It is not our intention to justify every
equation and procedure set down below to the uninitiated. For this reason, the "Correct" program
supplied with the instrument is highly recommended.
To set up a calibration on the PQ100 to "Engineering Standard Conditions" the following
applies;
PS TI
QI = QS ( ----- x ----- ) Equation #1
PI TS
where;
QS is the Standard Condition (PQ100 Target) flow rate in Liters per minute
(Lpm)
QI is the calibrator reading (Lpm) at a given Time, Temperature and
Barometric Pressure
PS is the Standard Condition Barometric Pressure (760) in millimeters of
mercury (mm of Hg) (Equal to 1013.25 HectoPascals)
PI is the Indicated Barometric Pressure reading (mm of Hg.) at the time of the
calibrator flow reading
TS is the Standard Condition Temperature (20) in degrees Celsius
TI is the Indicated Temperature reading (degrees Celsius) at the time of the
calibrator flow reading
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