Brooks Instrument 5850i - Manual (Page 48)

Brooks ® Model 5850i
4-20
Section 4 Maintenance Installation and Operation Manual
X-TMF-5850i-MFC-eng
Part Number: 541B108AAG
December, 2008
Table 4-5 Model 5850i Standard Restrictors
Example:
The desired gas is Silane (SiH4).
The desired full scale flow rate is 200 sccm
Sensor conversion factor is 0.68 from Table 4-3.
Air equivalent flow = 200/0.68 = 294.1 sccm air.
In the example above, a size P restrictor would be selected.
NOTE: If the calculated flow rate is such that two different size restrictors
could be used, always select the larger size.
If a mixture of two or more gases are being used, the restrictor selection
must be based on the air equivalent flow rate of the mixture.
Example:
The desired gas is 20% Helium (He) and 80% Chlorine (CI
2
) by volume.
The desired full scale flow rate of the mixture is 20 slpm.