The 640B absolute pressure controller is a self-contained, compact, closed-loop electronic pressure control system containing a Baratron® capacitance manometer, normally closed proportioning control valve, and closed-loop control electronics. Electrically similar to a standard MFC, the 640B is powered by ±15 VDC at only 200 mA, permitting use with standard power supply and display electronics. The pressure output and input control signals are linear 0-5 or 0-10 VDC. Two trip points with LED status indicators are for use as simple on/off process limits.
50, 200, 1000, 5000, 10000, 20000, 50000 sccm (nominal Full Scale flow rates for N2 with 15 psig on inlet and atmosphere on outlet)
Trip Points
Two open-collector transistors Rated: 250 mA @ 30 VDC Adjustable: 1 to 100% of Full Scale Hysteresis: 3% of Full Scale Indicators: Green LED's on when actuated
Pressure Control Accuracy
±0.2% of Full Scale
Transducer Over Pressure Limit
45 psia or 2x Full Scale, whichever is greater
Maximum Differential Pressure
30 psi for 20,000 and 50,000 sccm orifices 150 psi for 50 to 10,000 sccm orifices (consistent with transducer overpressure limit)
Control Mode
Downstream standard; Upstream optional
Pressure Measurement Accuracy
±0.5% of Reading (includes linearity, hysteresis, and repeatability)
Zero Temperature Coefficient
Zero: ±0.02% of Full Scale/°C
Span Temperature Coefficient
Span: ±0.04% of Reading/°C
Control Range
>2 to 100% of Full Scale
Typical Response Time
<1.0 sec (excluding system time constant)
Operating Temperature
0 - 50°C (32° to 122°F)
Storage Temperature
-20 to 80°C (-4° to 176°F)
External Leak Integrity
<10-9 scc/sec He
Leak Integrity Through Closed Valve
Elastomer valve: <10-4 scc/sec He Metal valve: <1% of Full Scale (N2 @ 1 atm. ΔP) Kel-F valve: <0.5% of Full Scale (N2 @ 1 atm. ΔP) (through closed valve)*
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