5850EM Metal Sealed Mass Flow Controller0 pages

1
Data Sheet
DS-TMF-5850EM-MFC -eng
October, 2008
Brooks® Model 5850EM
Metal Sealed Mass Flow Controller
Model 5850EM
Mass Flow Controller
with D-Connector
Model 5850EM Downported
Mass Flow Controller
with Card Edge
GENERAL FEATURES AND BENEFITS
• High leak integrity (less than 10-10 atm-cc/sec He)
• Enhanced process (5 Ra avg.) internal finish (optional)
• Electropolished wetted surfaces (optional)
• Vented-polished internal threads
• Normally Closed Valve (Normally Open Valve optional)
• Wide flow range (0.06 sccm through 30,000 sccm N2)
• Insensitive to mounting attitude
• Mechanically and electrically compatible with other
mass flow controllers
• Electrically activated valve override
• Low command flow cutoff
• TTL compatible "valve off" and purge function
• 0(4)-20 mA I/O, 24 Vdc, i-series design (optional)
• Available with all popular process connections
• Downport C-Seal (optional)
DESCRIPTION
The Brooks® Model 5850EM Metal Sealed Mass Flow
Controller has all the features of the standard Model
5850E plus all metal seals for outstanding leak integrity
and cleanliness. The Model 5850EM eliminates the need
for continuous monitoring and readjustment of gas
pressures to provide a stable mass flow. The heart of the
system is the highly stable sensor which produces an
electrical output signal linear with flow rate. This signal is
used for indicating, recording and/or control purposes
without the need for an auxiliary auto-zero circuit.
PRINCIPLE OF OPERATION
The operating principle of the Brooks Mass Flow
Controller is thermodynamic. A precision power supply
directs heat to the midpoint of the sensor tube carrying
the flow. On the same tube equidistant upstream and
downstream of the heat input, are resistance temperature
measuring elements.
With no flow, the heat reaching each temperature element
is equal. With increasing flow, the flowstream carries heat
away from the upstream element, T1 and an increasing
amount towards the downstream element T2. An
increasing temperature difference develops between the
two elements and this difference is proportional to the
amount of gas flowing or the mass flow rate. A bridge
circuit interprets the temperature difference and an
amplifier provides the output to the control circuitry as
well as a 0-5 Vdc output signal.
The control circuitry compares the command set-point
to the flow signal and positions the precision solenoid
control valve. When the command signal is below 1% of
full scale, the control valve is positioned fully closed. The
control valve can be latched fully open or closed by
activating the valve override circuit.
SPECIFICATIONS
Performance Characteristics:
Flow Ranges*
Any range from 0 to 3 sccm to -30,000 sccm Nitrogen
equivalent. Lower flows available, consult factory.
*Standard: 0°C and 101 kPa (760 Torr). Per SEMI Guideline E12-96.
Control Range
2 - 100% with elastomeric valve seat
3 - 100% with metal or Teflon® valve seat