Instructions for Use
– SCHMIDT
®
Flow Sensor SS 20.500
Page 12
According to this, the volumetric flow in a square duct is calculated as
follows:
𝐴
𝐻
=
𝜋
4
∙ 𝐷
𝐻
2
=
𝜋
4
∙ (
2 ∙ 𝑏 ∙ ℎ
𝑏 + ℎ
)
2
= 𝜋 ∙ (
𝑏 ∙ ℎ
𝑏 + ℎ
)
2
𝑤
̅
𝑁
= 𝑃𝐹 ∙ 𝑤
𝑁
𝑉̇
𝑁
= 𝑤
̅
𝑁
∙ 𝐴
𝐻
b
Width of square duct [m]
h
Height of square duct [m]
D
H
Inner diameter of equivalent pipe [m]
A
H
Cross section area of equivalent pipe [m
2
]
N
w
Standard flow velocity in pipe centre [m/s]
N
w
Average standard flow velocity in tube [m/s]
PF
Profile factor
N
V
Standard volumetric flow [m³/s]
Typical applications are:
o
Ventilation shaft
o
Exhaust air duct
