Brooks Instrument 5850E - Manual (Page 52)

4-20
Installation and Operation Manual
X-TMF-5850E-MFC-eng
Part Number: 541B102AAG
September, 2009
Section 4 Maitenance &
Troubleshooting
Brooks ® Model 5850E
Figure 4-4 Example Nomograph
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
3. Determine Critical Pressure Drop
Critical pressure drop occurs when the outlet pressure (psia) is less
than half the inlet pressure (psia) or
P outlet < P inlet
2
If these conditions exist, the pressure drop (Dp) should be calculated
as follows:
P
in
Dp =
2
Dp = Pressure drop (psi)
P
in
= Inlet pressure (psia)
If these conditions do not exist, pressure drop equals the inlet pressure
minus the outlet pressure.