Meriam 70H_72H High Pressure Wet Tap Accutubes with Integral 3-Valve Head and Optional RTD - Manual (Page 29)

29
9 FLOW CALCULATIONS
Flow Equations*
1. Any Liquid
Q(GPM) = 5.668 x K x D
i
2 x ∆ P/S
f
2. Steam or Any Gas**
Q(lb/Hr) = 359.1 x K x D
i
2 x ρ x ∆P
3. Any Gas P x ∆ P
Q(SCFM) = 128.8 x K x D
i
2 x (T + 460) x S
s
Differential Pressure Equations*
1. Any Liquid
Q 2 x S
f
∆P (In. WC) = K 2 x D
i
4 x 32.14
2. Steam or Any Gas**
Q 2
∆P (In. WC) = K 2 x D
i
4 x ρ x 128,900
3. Any Gas
Q 2 x S
s
x (T + 460)
∆P (In. WC) = K 2 x D
i
4 x P x 16,590
Technical Notations
The following notations apply:
∆ P = Differential pressure expressed in inches of water column
Q = Flow expressed in GPM, SCFM of PPH as shown in equation
K = Flow coefficient - See table 9.1 & 9.2
D
i
= Inside diameter of line size expressed in inches - For Inline Series see Table 9.3
For square and 4 x Height x Width
rectangular ducts use D
i
= π
P = Static Line pressure (psia)
T = Temperature in degrees Fahrenheit (plus 460 =
°Rankine)
ρ = Density of medium in pounds per cubic foot
S
f
= Liquid Sp. Gr. (density of liquid at flowing temperature / density of water at 60 °F)
S
s
= Gas Sp. Gr. (MWgas / MWair)
*Consult Flow Handbook F/N 957:081 For Equation Derivation and for correction factors for precise
calculations.
**Use of Accutubes on steam applications generating less than 10” wc differential pressure at normal flow
rate is not recommended. Reducing pipe size at the meter location may resolve this potential problem.