SLA7840AZ638 is a configured Brooks Instrument Model SLA7840 high-purity, metal-sealed remote-transducer pressure/flow controller. The SLA7840 platform uses an external pressure-transducer signal, integral PID electronics and a co-planar valve to regulate pressure while measuring thermal mass flow. The A variant identifies analog I/O. Brooks documentation does not decode the Z638 configuration suffix, so the exact gas, full-scale flow, process connection, control orientation and calibration data require nameplate or manufacturer order-record evidence
Configurations vary. Verify the exact unit before choosing a replacement.
Z638; meaning not defined in the available Brooks SLA7840 documentation
Function
Pressure-control method
External pressure-transducer feedback with adjustable integral PID electronics and an integral co-planar control valve
Measurement
Flow-measurement principle
Thermal mass flow
SLA7840 family
Available full-scale flow ranges
Any range from 0–3 sccm through 0–30,000 sccm, nitrogen equivalent; exact configured range is not established by the model code
Flow control range
33:1
Flow accuracy
±1.0% of rate, including linearity, from 20–100% full scale; ±0.2% of full scale below 20% full scale
Flow repeatability
±0.20% of rate
Flow settling time
Less than 1 second to within ±2% full scale for a 0–100% step, per SEMI E17-91
External pressure-sensor input
Suitable for pressure sensors with output signals up to 0–10 VDC
Pressure control range
20:1
Pressure settling time
Less than 1 second typical for a 20–100% setpoint step with maximum 2% overshoot; actual response depends strongly on system design
Available process connections
1/4-in male VCR standard; C Seal (SEMI 2787.1), CS Seal (SEMI 2787.5) and W Seal (SEMI 2787.3) options; exact SLA7840AZ638 connection is not established
Ratings
Maximum operating pressure
500 psig
Leak integrity
Inboard-to-outboard helium leak rate: 1 × 10^-10 atm-scc/sec maximum
Environment
Ambient temperature
Operating: 0–60 °C (32–140 °F); non-operating: −25–100 °C (−13–212 °F)
External/internal seals: nickel; standard valve seat: 316L stainless steel
Wetted surface finish
32 µin Ra maximum
Analog I/O variant
Electrical connector
15-pin male D-connector
Supply
+15 VDC ±5%; traditional −15 VDC pin is ignored
Power requirement with valve
3.6 W typical; 4.0 W maximum
Setpoint input
0–5 VDC; accepts signals through 5.5 VDC (110% full scale); 360 kΩ minimum input resistance
Flow output
0–5 VDC into a 2 kΩ minimum load; indicates process variable through 5.5 VDC (110% full scale)
Calibration
Stored calibration sets
Up to 10 selectable gas calibration and flow-range data sets on the SLA7840 platform
What Does SLA7840AZ638 Mean?
Only the base model and analog-I/O variant can be decoded from Brooks documentation. The remaining suffix must not be used to infer configured process details.
Segment
Field
Interpretation
SLA7840
Base model
High-purity, metal-sealed digital remote-transducer pressure/flow controller with integral mass-flow measurement and control valve.
A
Electrical I/O variant
Analog I/O. Brooks identifies SLA7840A as the analog controller and SLA7840D as the DeviceNet variant.
Z638
Configuration suffix
Not decoded in the available Brooks documentation. Nameplate or Brooks order-record evidence is required before asserting gas, range, fitting, valve orientation or calibration details.
Analog Operating Modes
Flow-control modeMode-select signal open or disconnected.
Pressure-control modeMode-select signal grounded.
Remote pressure input0–10 VDC input; Brooks also describes operation with user-supplied 5 V or 10 V full-scale pressure sensors.
Calibration selectionAnalog units require the Brooks service tool to switch among stored calibration data sets.
