25
Technical data
Type 8746 Profibus, 8746 Analogue
6.7.7
operating gas is not air
If the operating gas is not air, determine the pressure loss as
follows:
1.
Read the air pressure-loss p
air
from the diagrams in Fig. 8 or
in Fig. 9
2.
Calculate the pressure loss p
gas
with the formula that is given
in Fig. 10
.
ρ
ρ
air
air
= pressure loss of the operating gas
air = pressure loss of air
ρ
= density of the operating gas at the standard conditions
according to DIN 1343 (P
N
= 1013.25 mbar, T
N
= 273.15 K)
ρ
air
= density of air at the standard conditions according to
DIN 1343 (P
N
= 1013.25 mbar, T
N
= 273.15 K)
Fig. 10:
Formula to calculate the pressure loss in an MFM
Example for argon gas that flows through an MFM with 1/2"
internal-threaded fluid connections:
1.
If the flow rate is 1400 l
N
/min then the air pressure-loss p
air
as given in Fig. 8 is 140 mbar.
2.
The pressure loss for argon gas at a flow rate of 1400 l
N
/min
is 164.4 mbar as given by the calculation in Fig. 11
.
argon
= 140 mbar
1.784
1.294
= 164.4 mbar
Fig. 11: Calculation of the pressure loss for argon gas
English
Summary of Contents for 8746
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