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Catalog North America

Brochures North America

Gas Flow Meter Calculation Formulas




formula-1

Actual Flow Rate:

Q0 = Actual flow rate

ρ0 = Specific gravity of measured gas (Air = 1)

p0 = Actual ABSOLUTE pressure in metering tube

T0 = Actual ABSOLUTE temperature
(Kelvin) in metering tube

(0° C = 273,15° K)
(20° C = 293,15° K) 

Flowmeter Design (Calibration) Conditions:

Q1 = Flow meter reading

ρ1 = Specific gravity of design gas (Air = 1)

p1 = ABSOLUTE design pressure
(calibration pressure)

T1 = ABSOLUTE design temperature
(Calibration temperature) 

Example 1

What is the maximum flow if flow meter EK-3NR is used for Carbon dioxide at 3 bar(g)/25°C?

Ex-3NR scale is

   • 1 - 12 ln/min Air at 0 bar(g)/ 20° C

Q1 = 12 ln/min
ρ1 = 1
p1 = (0 + 1,013) bar = 1,013 bar
T1 = 293,15° K

Q0 = ?
ρ0 = 1,529
p0 = (3+ 1,013) bar = 4,013 bar
T0 = 298,15° K

formula-2

Actual flow at 12 ln/min reading
Q0 = 19,15 ln/min CO2 at 3 bar(g)/ 25° C

Example 2

What is the actual flow if flow meter LH-JJ32 is used for Helium at 5 bar(g) / 10° C.

LH-JJ32 is calibrated for

    • 30 ln/min Nitrogen at 3 bar(g)/ 20° C

Q1 = 30 ln/min
ρ1 = 0,9672
p1 = (3 + 1,013) bar = 4,013 bar
T1 = 293,15° K

Q0 = ?
ρ0 = 0,1380
p0 = (5+ 1,013) bar = 6,013 bar
T0 = 283,15° K

formula-3

Actual flow at 30 ln/min reading
Q0 = 98,9 ln/min He at 5 bar(g)/ 10° C