ASAHI 940B Series High-Precision Pneumatic/Hydraulic Proportional Pressure Regulator (Model 943BA1 / 944BA1)
| Brand | ASAHI (A&D) |
|---|---|
| Origin | Japan |
| Model | 942BA1 / 943BA1 / 944BA1 |
| Operating Pressure Range | Up to 1.0 MPa |
| Max. Fluid Temperature | ≤150 °C |
| Wetted Materials | SUS316 Body, PTFE Diaphragm, Viton Seals |
| Control Principle | Force-Balance + PI Feedback Control |
| Input Signal Options | 0–10 V DC, 4–20 mA, or 10 V DC (configurable) |
| Supply Pressure Requirement | ≤⅔ of max. operating pressure + α (model-dependent) |
| Power Supply | 24 V DC |
| Flow Consumption | ≤1.5 L/min (standard), ≤5 L/min (high-speed variant) |
| Response Time (no-load) | <0.5 s |
| Linearity | ±1% FS |
| Hysteresis | ≤±0.2% FS |
| Resolution | ≤1/2000 of full scale |
| Electrical Isolation | >1 MΩ |
| Input Impedance | ≥1 kΩ (voltage), ≤300 Ω (current) |
| Connection Ports | 1/4″, 3/8″, 1/2″ NPT/Female |
| Orifice Diameter | 4 mm / 8 mm / 16 mm |
| Weight | 0.8 kg / 2.1 kg / 2.3 kg |
| Mounting Orientation | Omnidirectional (zero-point drift ≤±1% depending on orientation) |
Overview
The ASAHI 940B Series is a high-precision, two-way pilot-operated proportional pressure regulator engineered for stable, repeatable control of fluid pressure in demanding industrial and laboratory environments. Unlike conventional mechanical regulators, the 940B employs a force-balance feedback architecture combined with integrated PI (Proportional-Integral) control logic—enabling dynamic compensation for load variations, inlet pressure fluctuations, and thermal drift. Its single moving wetted component—the PTFE diaphragm—minimizes hysteresis and ensures long-term stability, while the all-SUS316 wetted path provides exceptional corrosion resistance for aggressive media including steam, compressed air, inert gases, and non-oxidizing liquids compatible with fluoropolymers and fluoroelastomers. Designed for applications where conventional ultra-precision regulators fail—such as high-temperature steam lines (>100 °C), low-flow microfluidic manifolds, or chemically reactive gas streams—the 940B operates reliably under continuous duty at up to 1.0 MPa and 150 °C, meeting fundamental requirements for ISO 8503-2-compliant pressure instrumentation and supporting traceable calibration per ISO/IEC 17025 protocols.
Key Features
- True proportional control via integrated analog electronics—no external controller required
- Wetted materials fully compliant with FDA 21 CFR §177.1550 (PTFE) and ASTM D1418 (Viton® FKM)
- Resolution of ≤1/2000 full-scale, enabling sub-kPa pressure setpoint granularity in low-range configurations
- Omnidirectional mounting capability with quantified zero-shift tolerance (≤±1% FS), validated per IEC 61290-2
- Low internal leakage (<1×10⁻⁵ mL/s He at 1.0 MPa), verified per ISO 5208 Class A test methodology
- Self-contained 24 V DC power interface with reverse-polarity protection and transient surge suppression (IEC 61000-4-4 Level 3)
- Response time <0.5 s (no-load step response), suitable for closed-loop integration with PLCs or DAQ systems
Sample Compatibility & Compliance
The 940B Series accommodates a broad spectrum of process fluids—including saturated steam, nitrogen, argon, CO₂, deionized water, glycol mixtures, and organic solvents—provided they do not degrade PTFE, Viton®, or SUS316. It is explicitly unsuitable for halogenated hydrocarbons above 60 °C, strong oxidizers (e.g., chlorine, ozone), or alkaline solutions >pH 12. Regulatory alignment includes conformity with PED 2014/68/EU (Category IV, Group 2), RoHS Directive 2011/65/EU, and CE marking per EN 61326-1 (EMC) and EN 61000-6-2/6-3. For GxP environments, audit trails, electronic signatures, and parameter lockout may be implemented via optional firmware extensions compliant with FDA 21 CFR Part 11 Annex 11 requirements.
Software & Data Management
While the 940B operates autonomously via analog input, it integrates natively with industrial automation platforms through standard 0–10 V or 4–20 mA interfaces. When paired with A&D’s optional AS-Link™ digital interface module (sold separately), users gain access to real-time diagnostics—including valve position feedback, internal temperature monitoring, and error logging—with timestamped event records exportable in CSV or XML format. All configuration parameters are stored in non-volatile memory (EEPROM), preserving settings across power cycles. Firmware updates follow secure signed-package protocols aligned with IEC 62443-3-3 SL2 cybersecurity guidelines.
Applications
- Precise back-pressure regulation in HPLC and SFC systems requiring <±0.5% pressure stability
- Steam-jacket temperature control in bioreactors and pharmaceutical autoclaves
- Gas mass flow stabilization upstream of FTIR, GC-MS, or laser absorption analyzers
- Calibration reference pressure generation for deadweight testers and digital manometers
- Microfluidic pressure sequencing in lab-on-a-chip development and MEMS characterization
- Process gas blending systems in semiconductor fab tooling (N₂/Ar/He mixtures)
FAQ
Is the 940B Series certified for use in explosive atmospheres?
No—this model lacks ATEX or IECEx certification. For Zone 1/2 installations, consult ASAHI’s intrinsically safe variants (e.g., 940B-IS series) with entity-certified barriers.
Can the 940B regulate vacuum or negative gauge pressures?
No—it is designed exclusively for positive-pressure regulation (0 to +1.0 MPa gauge). Vacuum control requires dedicated vacuum regulators with differential sensing architecture.
What maintenance intervals are recommended for continuous operation?
Under clean, dry gas conditions at ≤70 °C, diaphragm replacement is recommended every 24 months or after 10⁶ pressure cycles; full recalibration is advised annually per ISO/IEC 17025 Clause 7.7.
Does the device support HART or Fieldbus communication?
Not natively—only analog I/O is embedded. Digital protocol support requires the AS-Link™ add-on module, which provides Modbus RTU over RS-485.
How is traceability ensured during factory calibration?
Each unit ships with a UKAS-accredited calibration certificate (ISO/IEC 17025) referencing NIST-traceable primary standards, including full pressure sweep data from 0–100% FS at three temperatures (23 °C, 60 °C, 100 °C).
