5850EM Metal Sealed Mass Flow Controller - Brooks Instrument - #1

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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