Bronkhorst®
Instruction Manual EL-FLOW® Classic series
9.17.085D
14
4
Advanced operation
4.1
Using other gases than specified
Each instrument has been calibrated and adjusted for customer process conditions.
Controllers or valves may not operate correctly, if process conditions vary too much, because of the restriction of the orifice
in the valve. The performance and accuracy of thermal Mass Flow Controllers may be affected tremendously if physical
fluid properties such as heat capacity and viscosity change due to changing process conditions.
4.2
Conversion factor calculation
Bronkhorst has gathered the physical properties of over 600 fluids in a database called FLUIDAT® This database also
provides a collection of routines to calculate physical properties of gases and liquids, not only at 20°C/1 atm but at any
temperature/pressure combination, both for gases and for liquids.
Check FLUIDAT® on the Net on
http://www.fluidat.com
Consult your distributor for more details.
Also see section
Calibration
.
4.3
Maximum pressure drop
For (pilot) solenoid operated control valves with small orifices, the maximum allowable pressure drop for gases is according
to the table.
Diameter [mm]
Kv
Normally closed
D
p max. [bard]
0,05
4,33 x 10
-5
30
0,07
8,48 x 10
-5
30
0,10
1,73 x 10
-4
30
0,14
3,39 x 10
-4
30
0,20
6,93 x 10
-4
30
0,30
1,56 x 10
-3
30
0,37
2,37 x 10
-3
30
0,50
4,33 x 10
-3
30
0,70
8,48 x 10
-3
24
1,00
1,73 x 10
-2
12
1,30
2,93 x 10
-2
8
1,50
3,90 x 10
-2
6
1,70
5,00 x 10
-2
5
2,00
6,63 x 10
-2
3,6
