Register to enable "Calculate" "Calculate" button. t support Java, or Java is disabled in your browser. Calculation should be here. Units: bbls=barrels, C=degrees Celsius, cm=centimeter, cP=centipoise, cSt=centis Types of Pressure Taps for Small Bore Orifices:
Topics: Introduction Equations Discharge Coefficients Error Messages References Introduction
Orifice flow meters are used to determine a liquid or gas flow rate by measuring t The LMNO Engineering small diameter orifice calculation is valid for orifices instal Equations To top of page The calculations on this page are for orifices carrying a liquid as described in ASM
w is the static pressure loss occurring from a distance of approximately D upstrea of the orifice. It is not the same as differential pressure. Differential pressure is m (shown in the above figures). Km is computed to allow you to design pipe systems 2
computed as h=KmV /(2g) where V is the pipe velocity. Discharge Coefficients (ASME, 2001) To top of page Corner Taps:
Flange Taps:
where D is in inches; and d/D and Re D are dimensionless. C is dimensionless. Applicability: Pipe Diameter, D LMNO Engineering calculation requires 1 cm < D < 5.1 cm for both corner and fla ASME (2001) suggests 1.2 cm <= D <= 4 cm for corner taps and 2.5 <= D <= 4 cm f Diameter ratio, d/D LMNO Engineering and ASME (2001) require 0.1 <= d/D <= 0.8 for corner taps an Reynolds number based on pipe diameter, ReD LMNO Engineering and ASME (2001) require ReD > 1000. Error Messages given by calculation To top of page Messages indicating input values are out of the acceptable ranges: 3
2
"Need 1
References To top of page American Society of Mechanical Engineers (ASME). 2001. Measurement of fluid fl International Organization of Standards (ISO 5167-1). 1991. Measurement of flui International Organization of Standards (ISO 5167-1) Amendment 1. 1998. Meas
toke, F=degrees Fahrenheit, cfs=cubic feet per second, ft=feet, g=gram, gpm=US gallons per minute, gph=US g
he differential pressure (P1 - P2) across the orifice plate. The two standard pressure tapping arrangements for lled in pipes having pipe diameters between 1 cm and 5 cm (2 inch), and pipe Reynolds numbers greater than
E (2001). Inlet Orifice ( No.1,2,3)
m of the orifice to a distance of approximately 6D downstream easured at the exact locations specified in ASME (2001) with orifices and incorporate their head loss. Head loss is
ge taps. or flange taps.
0.15 <= d/D <= 0.7 for flange taps.
3
<0.051 m", "Need 1e-30
will cause Re D to be < 1000 (out of range of validity). erential pressure that you entered will cause the throat velocity to exceed 1000 m/s, a velocity for which the ute d; value for d will cause d/D to be out of range of validity.
ice Calculation for Liquids based on ISO 5167. Or, try the simpler orifice calculation on our Bernoulli page if yo
low using small bore precision orifice meters. ASME MFC-14M-2001. flow by means of pressure differential devices, Part 1: Orifice plates, nozzles, and Venturi tubes inserted in ci rement of fluid flow by means of pressure differential devices, Part 1: Orifice plates, nozzles, and Venturi tub
allons per hour, gpd=US gallons per day, hr=hour, kg=kilogram, lb=pound, m=meters, min=minute, mm=
small bore orifices are shown in the drawings; the location of the pressure taps affects the discharge coe 000. For larger diameter pipes, please see our Large Diameter Orifice Calculation for Liquids. We also ha
Re D > 1000".
alculation is not valid. The calculation is not valid for supersonic flows.
ur parameters are out of range. The Bernoulli calculation is not as accurate, but won't give "parameter o
rcular cross-section conduits running full. Reference number: ISO 5167-1:1991(E). s inserted in circular cross-section conduits running full. Reference number: ISO 5167-1:1991/Amd.1:199
illimeter, N=Newton, Pa=Pascal, psi=pound per square inch, s=second
ficient somewhat. Flange pressure taps penetrate the flange and are at a standard distance of 1 inch (2. ve orifice calculations for gas flow (D<5 cm and D> 5 cm); and calculations for flow through nozzle and ve
t of range" error messages.
8(E).
4 cm) from either side of the orifice. For corner taps, tappings are right up against the orifice. nturi flow meters.
Qm= C= Athroat = β= d/D = ρ= ∆p = sq. root(2*ρ*∆p) = C=
a = β^4 = ReD = ʋ (kinematic viscosity) Vpipe (m/s) =
C* Athroat * sq. root( 0.60654639 ∏/4 * d2 = 2.73E-05 0.374365482 d= 0.0059 681 (density Kg/m3) 441300 ( Differential pressure N/m2 24516.33333 [0.598 + 0.468 (a+10*a^3)]* sq.root(1-a) + (0.8
0.019641886 Vpipe * D /ʋ =
a^3 36799.4 sq. root ReD =
(dynamic viscosity in cP) / 1000* ρ = 1.0252
2*ρ*∆p) / sq. root (1- β^4) = Qv (m3/s) = Qv (l/min) = D=
0.410602 0.000603 36.17639
0.01576
) +8.1a)*sq.root{(1-a)/ReD)} =
7.57791E-06 191.8316963 4.3906E-07
sq. root(1-a) =
0.99013
Qm= C= Athroat = β= d/D = ρ= ∆p = sq. root(2*ρ*∆p) = C=
a = β^4 = ReD = ʋ (kinematic viscosity) Vpipe (m/s) =
C* Athroat * sq. root(2*ρ*∆p) / sq. r 0.60156565 ∏/4 * d2 = 8.04E-06 0.203045685 d= 0.0032 D= 681 (density Kg/m3) 2741300 ( Differential pressure N/m2) 61103.60546 [0.598 + 0.468 (a+10*a^3)]* sq.root(1-a) + (0.87+8.1a)*sq.roo
0.001699711 Vpipe * D /ʋ =
a^3
4.91049E-09
72507.6 sq. root ReD =
(dynamic viscosity in cP) / 1000* ρ = 2.02
269.2723454 4.3906E-07
Qv (back calculated)=
oot (1- β^4) = Qv (m3/s) = Qv (l/min) =
0.295876 0.000434 26.06833
0.01576
t{(1-a)/ReD)}
=
sq. root(1-a) =
0.000394
23.634
0.99915
Qm= C= Athroat = β= d/D = ρ= ∆p = sq. root(2*ρ*∆p) = C=
a = β^4 = ReD = ʋ (kinematic viscosity) Vpipe (m/s) =
C* Athroat * sq. root(2*ρ*∆p) / sq. r 0.59990414 ∏/4 * d2 = 3.31E-05 0.203045685 d= 0.0032 D= 681 (density Kg/m3) 2441300 ( Differential pressure N/m2) 57663.25173 [0.598 + 0.468 (a+10*a^3)]* sq.root(1-a) + (0.87+8.1a)*sq.roo
0.001699711 Vpipe * D /ʋ =
a^3
4.91049E-09
297927.3 sq. root ReD =
545.8271254
(dynamic viscosity in cP) / 1000* ρ = 8.3
4.3906E-07
Qv (back calculated)=
oot (1- β^4) = Qv (m3/s) = Qv (l/min) =
1.144509 0.001681 100.8378
0.01576
t{(1-a)/ReD)}
=
sq. root(1-a) =
0.001619
97.11
0.99915
Qm= C= Athroat = β= d/D = ρ= ∆p = sq. root(2*ρ*∆p) = C=
a = β^4 = ReD = ʋ (kinematic viscosity) Vpipe (m/s) =
C* Athroat * sq. root(2*ρ*∆p) / sq. r 0.611688502 ∏/4 * d2 = 5.03E-05 0.507614213 d= 0.008 D= 681 (density Kg/m3) 581300 ( Differential pressure N/m2) 28137.7078 [0.598 + 0.468 (a+10*a^3)]* sq.root(1-a) + (0.87+8.1a)*sq.roo
0.066394957 Vpipe * D /ʋ =
a^3
0.000292688
288063.3 sq. root ReD =
536.7153307
(dynamic viscosity in cP) / 1000* ρ = 8.0252
4.3906E-07
Qv (back calculated)=
oot (1- β^4) = Qv (m3/s) = Qv (l/min) =
0.89538 0.001315 78.88809
0.01576
t{(1-a)/ReD)}
=
sq. root(1-a) =
0.001565
93.89484
0.966232
Throat bush area changed to eq
Qm= C= Athroat = β= d/D = ρ= ∆p = sq. root(2*ρ*∆p) = C=
a = β^4 = ReD = ʋ (kinematic viscosity) Vpipe (m/s) =
C* Athroat * sq. root(2*ρ*∆p) / sq. r 0.602480713 ∏/4 * d2 = 2.46E-05 0.355329949 d= 0.0056 D= 681 (density Kg/m3) 2741300 ( Differential pressure N/m2) 61103.60546 [0.598 + 0.468 (a+10*a^3)]* sq.root(1-a) + (0.87+8.1a)*sq.roo
0.015941429 Vpipe * D /ʋ =
a^3
4.05118E-06
288063.3 sq. root ReD =
536.7153307
(dynamic viscosity in cP) / 1000* ρ = 8.0252
4.3906E-07
uivalent orifice dia
oot (1- β^4) = Qv (m3/s) = Qv (l/min) =
0.914041 0.001342 80.5322
4.831932
0.01576 Throat bush clearance area =
t{(1-a)/ReD)}
=
sq. root(1-a) =
0.991997
2.42E-05
Bush ID Shaft OD 0.07022 0.07
