Model 5964D High Performance Metal Sealed Mass Flow Controller - Brooks Instrument - #1

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1 Data Sheet DS-TMF-5964-MFC-eng October, 2008 High Performance Metal Sealed MFC Model 5964D High Performance Metal Sealed Mass Flow Controller Model 5964D Mass Flow Controller with VCR Features and Benefits • Electropolished wetted surfaces (optional) • Enhanced process (5 Ra avg.) internal finish • All metal seals • Particulate free • High purity VAR 316L stainless steel • Enhanced response to command changes • Helium leak check ports • Class 100 assembly and calibration • High leak integrity (less than 10-10 atm-cc/sec He) • Normally Closed Valve (Normally Open Valve optional) • Wide flow range (0.06 sccm through 30,000 sccm N2) • Insensitive to mounting attitude • Electrically activated valve override • Low command flow cutoff • TTL compatible "valve off" and purge function • Available with all popular process connections • Downport C-Seal or W-Seal (optional) Description The Brooks® Model 5964 Metal Sealed Mass Flow Controller offers state of the art performance in gas flow measurement and control. It combines the outstanding leak integrity of metal seals, ultraclean internal surface finish (5 Ra avg.) for particulate-free delivery and enhanced response for rapid process applications. The superior design also allows for very rapid gas changeover. All of this makes the Model 5964D the best solution for even the most challenging application. 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 Principle of Operation (continued) 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. Figure 1 Principle of Operation ± 15 Vdc Flow Amplifier Heater 0-5 Vdc Bypass Sensor Tube T2 Downstream Temperature Sensor To Power Supply T1 Upstream Temperature Sensor Bridge for ÄT Detection