Endress+Hauser Proline Promass E TB2 HART Operating Instructions Manual page 104

Technical data
Pressure loss
104
• The minimum recommended full scale value is approx. 1/20 of the maximum full scale value
• In most applications, 20 to 50% of the maximum full scale value can be considered ideal
• Select a lower full scale value for abrasive substances (such as liquids with entrained solids): flow
velocity <1 m/s (<3 ft/s).
• For gas measurement the following rules apply:
– Flow velocity in the measuring tubes should not be more than half the sonic velocity (0.5 Mach).
– The maximum mass flow depends on the density of the gas: formula (® ä 97)
To calculate the pressure loss, use the Applicator sizing tool(® ä 94)
Pressure loss in SI units
Pressure loss depends on the fluid properties and on the flow rate. The following formulas can be
used to approximately calculate the pressure loss:
Reynolds number
Re ³ 2300 *
Re < 2300
Dr = pressure loss [mbar]
n = kinematic viscosity [m
2 /s] g = mass flow [kg/s]
* To calculate the pressure loss for gases, always use the formula for Re ³ 2300.
Pressure loss coefficients
DN
[mm] [in]
8 3/8
15 ½
25 1
40 1½
50 2
Re =
p
p = K ·
D
Dp = K1 · ·
r = fluid density [kg/m
d = inside diameter of measuring tubes [m]
K to K2 = constants (depending on nominal diameter)
d K
[m]
–3
5.35× 10 5.70× 10
–3
8.30× 10 7.62× 10
–3
12.00× 10 1.89× 10
–3
17.60× 10 4.42× 10
–3
26.00× 10 8.54× 10
Proline Promass E TB2 HART
2 ·
g
· d · ·
n r
0.25 1.85 –0.86
· ·
g
n r
0.25 2
K2 · ·
g
n
+
g
n
r
3 ]
K1
7 7
7.91× 10
6 7
1.73× 10
6 6
4.66× 10
5 6
1.35× 10
4 5
4.02× 10
Endress+Hauser
A0004623
A0004626
A0004628
K2
7
2.10× 10
6
2.13× 10
5
6.11× 10
5
1.38× 10
4
2.31× 10