Kobold MAS, Руководство по эксплуатации

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MAS
MAS K05/0722 page 15
13. Conversion to other Working Conditions
The flow rate of your MAS is referenced to certain “standard” Conditions of
temperature and pressure. Unless otherwise specified in your order, these
standard conditions are 21
°
C (70
°
F) and 760 mm of mercury (1 atmosphere). If
you wish to convert to other “standard” conditions or to find the “actual” conditions
in the pipe where your MAS is installed, use the following relationship:
1
1
2
2
1
2
xQ
T
T
x
P
P
Q
=
( )
1
= Refers to the standard conditions with which your MAS was calibrated
( )
2
= Refers to the new standard conditions or to the actual temperature and
pressure conditions in the pipe,
Q
1
= The gas mass flow rate referenced to the calibrated standard conditions
(SCCM or SLM),
Q
2
= The gas mass flow rate referenced to the new standard or actual conditions
(SCCM or SLM–“S” means “standard”; ACCM or ALM–“A” means “actual”),
P = Absolute pressure (kg/cm2 or psia), and
T = Absolute temperature (°K or °R) °K = °C + 273; °R = °F + 460)
Example 1 changing „standard“ conditions
If your MAS has a flow rate reading of 10.00 SLM and was calibrated at standard
conditions of 70 °F (21 °C) and 1 atmosphere (14.7 psia), and if you wish to
convert this reading to standard conditions of 32 °F (0 °C) and 1 atmosphere,
then you would use the equation as follows:
1 2
) 21 273 (
273
.) ( 1
.) ( 1
xQ
K K
K
x
abs bar
abs bar
Q
+
=
min / 28 , 9 min / 10 928 , 0
2
Nl Nl x Q
= =
So, you can see that the flow rate referenced to 0 °C will be approximately 7%
lower than when referenced to conditions of 21 °C.
Example 2 Finding the “Actual” flow rate
If the flow rate and calibrated standard conditions are as given in Example 1 and
you wish to find the actual flow rate at 100 °F and 30 psig, then you would use
equation as follows:
Q
2
=
30 7 . 14
7 . 14
+
70 460
100 460
+
+
(10.00) = 3.47 slm