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Section 4 Maintenance &
Troubleshooting
Brooks
®
Model 585xEMH
4-18
Restrictors
The Model 585xEMH mass flow controller/device uses the Anti-Clog
Laminar Flow Element (A.C.L.F.E.).
Sizing
All Model 585xEMH Series Restrictor Assemblies are factory adjusted to
provide a specific pressure drop for each flow rate. This corresponds to the
desired full scale flow rate. Contacts Brooks Instrument for recommended
restrictor size and part number.
Example:
The desired gas is Silane (SiH4).
The desired full scale flow rate is 200 sccm. Sensor conversion factor is
0.625 from Table 4-3.
Nitrogen equivalent flow = 200/0.625 = 320 sccm Nitrogen
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 is being used, the restrictor selection
must be based on a Nitrogen equivalent flow rate of the mixture.
Example:
The desired gas is 20% Helium (He) and 80% Chlorine (Cl) by volume.
The desired full scale flow rate of the mixture is 20 slpm. Sensor
conversion factor for the mixture is:
Nitrogen equivalent flow = 20/.945 = 21.16 slpm Nitrogen. In this example
a Size 4 Wire Mesh Assembly would be selected.
Installation and Operation Manual
X-TMF-585xEMH-MFC-eng
Part Number: 541B212AAG
February, 2016
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