4-12
Brooks
®
Models 5964, 5850EM
Section 4 Maintenance
Installation and Operation Manual
X-TMF-5964-5850EM-MFC-eng
Part Number: 541B121AHG
November, 2008
Example:
Q
gas
=
2,000 sccm
=
2,000 x .269
=
538 sccm Nitrogen
In order to calculate the orifice conversion factor when using a gas mixture,
the following formula must be used:
Where
P
1
=
percentage by volume of gas 1
P
2
=
percentage by volume of gas 2
P
n
=
percentage by volume of gas n
Example: Find the Nitrogen equivalent for 20 slpm of a 20% Helium and
80% Chlorine gas mixture.
Q
Nitrogen
=
Q
gas
(orifice conversion factor)
=
20 x 1.439
=
28.78 slpm Nitrogen
2. If inlet and outlet pressures are given in gauge pressure (psig) add 14.7
to convert to absolute pressure (psia).
Outlet Pressure — 30 psig + 14.7 = 44.7 psia
Inlet Pressure — 50 psig + 14.7 = 64.7 psia
