Flow Rate To Actual Flow Rate - TSI Alnor LoFlo Balometer El Manual Del Propietario

Correction Factors for Standard Flow Rate to Actual Flow Rate
®
The LoFlo Balometer Capture Hood measures
standard volumetric flow rate. Standard flow is defined
as the flow rate at standard conditions, 70°F (21.1°C)
and 14.7 psia (29.92 inHg, 760 mmHg). Actual flow
rate is the true volumetric rate of air at the local
temperature and barometric pressure. If you desire
standard flow rate, use the displayed reading.
However, if the actual flow rate is desired, use the
information below.
To correct the standard flow rate to actual flow rate use
the equation below.
V act = V std x CF
V act = Actual flow rate
V std = Standard flow rate (this is displayed by
the instrument)
T act = Actual Temperature
ρ act = Actual barometric pressure
ρ std = Standard density 0.075 lb/ft
(at 70°F and 14.7 psia)
ρ a
= Actual density in lb/ft
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APPENDIX A
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CF = ρ
/ρ (Correction Factor)
std a
Using the equations or chart below, you can bypass the
full density calculation.
Calculations in imperial units
CF = (14.7/ ρ act )*(460+ T act )/530
Where ρ act is in psia and T act is in °F
Calculations in imperial units
CF = (29.92/ ρ act )*(460+ T act )/530
Where ρ act is in inHg and T act is in °F
Calculations in metric units
CF = (760/ ρ act )*(273.15+ T act )/294.25
Where ρ act is in mmHg and T act is in °C
For your convenience, we have made a chart for
determining the correction factor given temperature and
pressure.
 NOTE: The atmospheric pressure as reported by
the National Weather Service is corrected to sea
level and cannot be used if measurements are not at
sea level.
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