AIR FLOW METER CORRECTIONS
Mass Flow Meters
S
A
A
S
S
A
Q
=
Q (P /P x T /T )
A
S
S
A
A
S
Q
=
Q (P /P x T /T )
S
where;
Q is the STP flow rate
A
Q is the ambient flow rate
S
P is STP pressure
A
P is the ambient pressure
S
T is STP temperature
A
T is the ambient temperature
Rotameter Corrections
A
I
S
A
A
S
Q
=
Q
/
(P /P x T /T )
S
I
A
S
S
A
Q
=
Q
/
(P /P x T /T )
I
where;
Q is the rotameter flow indication
This correction assumes the rotameter markings are
correct at STP. If the rotameter was calibrated for other than
STP then other corrections must be applied.
Note: If the pressure inside the rotameter is less than
standard the rotameter will indicate higher than the true
standard flow rate but less than the ambient (actual or
volumetric) flow rate.
If the rotameter is downstream from the sampling head
then the ambient pressure inside the rotameter will be less than
the local atmospheric pressure. The ambient pressure inside
the rotameter should be used in the calculations.
For personnel protection against particulate airborne
radioactivity ambient sample volumes instead of volumes
corrected to STP should be used for calculations. The ambient
respiratory rate will remain the same as atmospheric pressure
changes from STP up to an elevation of approximately 12,000
feet (3,660 Meters).
AIR FLOW METER CORRECTIONS
Mass Flow Meters
S
A
A
S
S
A
Q
=
Q (P /P x T /T )
A
S
S
A
A
S
Q
=
Q (P /P x T /T )
S
where;
Q is the STP flow rate
A
Q is the ambient flow rate
S
P is STP pressure
A
P is the ambient pressure
S
T is STP temperature
A
T is the ambient temperature
Rotameter Corrections
A
I
S
A
A
S
Q
=
Q
/
(P /P x T /T )
S
I
A
S
S
A
Q
=
Q
/
(P /P x T /T )
I
where;
Q is the rotameter flow indication
This correction assumes the rotameter markings are
correct at STP. If the rotameter was calibrated for other than
STP then other corrections must be applied.
Note: If the pressure inside the rotameter is less than
standard the rotameter will indicate higher than the true
standard flow rate but less than the ambient (actual or
volumetric) flow rate.
If the rotameter is downstream from the sampling head
then the ambient pressure inside the rotameter will be less than
the local atmospheric pressure. The ambient pressure inside
the rotameter should be used in the calculations.
For personnel protection against particulate airborne
radioactivity ambient sample volumes instead of volumes
corrected to STP should be used for calculations. The ambient
respiratory rate will remain the same as atmospheric pressure
changes from STP up to an elevation of approximately 12,000
feet (3,660 Meters).
AIR FLOW METER CORRECTIONS
Mass Flow Meters
S
A
A
S
S
A
Q
=
Q (P /P x T /T )
A
S
S
A
A
S
Q
=
Q (P /P x T /T )
S
where;
Q is the STP flow rate
A
Q is the ambient flow rate
S
P is STP pressure
A
P is the ambient pressure
S
T is STP temperature
A
T is the ambient temperature
Rotameter Corrections
A
I
S
A
A
S
Q
=
Q
/
(P /P x T /T )
S
I
A
S
S
A
Q
=
Q
/
(P /P x T /T )
I
where;
Q is the rotameter flow indication
This correction assumes the rotameter markings are
correct at STP. If the rotameter was calibrated for other than
STP then other corrections must be applied.
Note: If the pressure inside the rotameter is less than
standard the rotameter will indicate higher than the true
standard flow rate but less than the ambient (actual or
volumetric) flow rate.
If the rotameter is downstream from the sampling head
then the ambient pressure inside the rotameter will be less than
the local atmospheric pressure. The ambient pressure inside
the rotameter should be used in the calculations.
For personnel protection against particulate airborne
radioactivity ambient sample volumes instead of volumes
corrected to STP should be used for calculations. The ambient
respiratory rate will remain the same as atmospheric pressure
changes from STP up to an elevation of approximately 12,000
feet (3,660 Meters).
AIR FLOW METER CORRECTIONS
Mass Flow Meters
S
A
A
S
S
A
Q
=
Q (P /P x T /T )
A
S
S
A
A
S
Q
=
Q (P /P x T /T )
S
where;
Q is the STP flow rate
A
Q is the ambient flow rate
S
P is STP pressure
A
P is the ambient pressure
S
T is STP temperature
A
T is the ambient temperature
Rotameter Corrections
A
I
S
A
A
S
Q
=
Q
/
(P /P x T /T )
S
I
A
S
S
A
Q
=
Q
/
(P /P x T /T )
I
where;
Q is the rotameter flow indication
This correction assumes the rotameter markings are
correct at STP. If the rotameter was calibrated for other than
STP then other corrections must be applied.
Note: If the pressure inside the rotameter is less than
standard the rotameter will indicate higher than the true
standard flow rate but less than the ambient (actual or
volumetric) flow rate.
If the rotameter is downstream from the sampling head
then the ambient pressure inside the rotameter will be less than
the local atmospheric pressure. The ambient pressure inside
the rotameter should be used in the calculations.
For personnel protection against particulate airborne
radioactivity ambient sample volumes instead of volumes
corrected to STP should be used for calculations. The ambient
respiratory rate will remain the same as atmospheric pressure
changes from STP up to an elevation of approximately 12,000
feet (3,660 Meters).
Page