803440-15 – Avox Systems Oxygen Regulator Assembly with Gauge 💨
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Overview
The Avox Systems (now Zodiac Aerospace/Safran) 803440-15 Oxygen Regulator Assembly is a precision, high-pressure gas control component designed for use in fixed oxygen systems on a variety of General Aviation (GA), corporate, and transport category aircraft. This assembly performs the flight-critical function of reducing the extremely high pressure contained within the aircraft's oxygen storage cylinder (typically 1800 to 2200 PSI) down to a manageable, low-pressure outlet suitable for pilot and passenger distribution and consumption (typically 40 to 90 PSI).
The complete assembly includes the primary pressure reduction mechanism, the necessary output valve connection ports, and an integrated high-pressure gauge. The gauge allows visual confirmation of the remaining oxygen supply pressure in the cylinder, which is essential for determining the remaining flight time at a safe oxygen level. The $-15$ dash number denotes a specific configuration, inlet port thread (e.g., CGA 540), and outlet pressure setting, ensuring system compatibility and crew safety at high altitudes.
Key Features
Two-Stage Pressure Reduction: Engineered to safely and reliably step down the cylinder's high storage pressure (up to 2200 PSI) to the low, controlled delivery pressure required by the distribution manifold.
Integrated High-Pressure Gauge: Features a calibrated Bourdon tube or diaphragm gauge mounted directly on the regulator body, providing pilots and mechanics with a real-time, accurate indication of cylinder contents.
Corrosion-Resistant Components: Constructed with materials (e.g., CRES or specially plated brass) resistant to oxidation and the internal effects of dry, high-pressure aviation breathing oxygen.
Safety Relief Mechanism: Includes a mandatory pressure relief device (burst disk or relief valve) to safely vent excess pressure in the event of regulator failure, protecting downstream components from over-pressurization.
High Flow Capacity: Designed to maintain the required delivery pressure and flow rate to multiple user stations simultaneously, as required by FAR 23.1441 and 25.1441.
Technical Specifications
Part Number: 803440-15
Component Type: High-Pressure Oxygen Regulator Assembly
OEM Manufacturer: Avox Systems (Safran/Zodiac Aerospace)
Input Pressure (Maximum): Typically 2200 PSI (High Pressure Cylinder Source).
Output Pressure (Nominal): Must be confirmed by CMM. Typically 40 PSI to 90 PSI regulated pressure.
Inlet Port Connection: Must be confirmed by CMM. Often CGA 540, AN900-2, or a proprietary threaded port.
Output Port Connection: Typically AN-threaded port for connection to the oxygen manifold/plumbing system.
Integrated Gauge: High-pressure reading gauge (0 to 3000 PSI range, typically).
Material: Forged Brass, CRES (Corrosion Resistant Steel), and specialized diaphragm/sealing materials.
Certification Status: FAA-TSO/PMA Approved for fixed oxygen systems.
Aircraft Compatibility
Primary Usage: Used as the main regulator in fixed oxygen systems across numerous aircraft types:
General Aviation: High-altitude piston singles and twins (e.g., Cessna P210, Piper Malibu, Beechcraft Baron).
Turboprop and Light Jet Aircraft: As the dedicated supply regulator for flight crew and passenger systems.
Verification Note: The Aircraft Maintenance Manual (AMM) and the Oxygen System Component Maintenance Manual (CMM) are the definitive and final authority for part applicability.
Applications Section
The 803440-15 regulator is indispensable for high-altitude flight safety:
Life Support Pressure Reduction: Safely reduces potentially lethal cylinder pressure to a usable, non-damaging level for delivery to demand regulators and masks.
Supply Monitoring: The integrated gauge provides the only direct, visual means for a flight crew to determine oxygen endurance during flight planning and execution.
System Isolation: Serves as the first point of control and pressure limiting for the entire downstream oxygen distribution system.
Why Choose the 803440-15 OEM Oxygen Regulator?
The oxygen regulator is a critical life-support component. Its failure due to inaccurate pressure reduction or internal component material fatigue is a safety hazard. Choosing the Avox 803440-15 OEM regulator guarantees precise, repeatable pressure regulation required to prevent both over-pressurization (which could rupture downstream lines and equipment) and under-pressurization (which results in insufficient oxygen flow at altitude). Avox regulators are certified for use with aviation-grade oxygen, ensuring internal sealing materials and diaphragms resist the oxidizing effects of dry oxygen and maintain performance consistency across extreme temperature changes.
The 803440-15 employs a multi-stage pressure reduction principle. The primary stage reduces the cylinder pressure to an intermediate, controlled level, and the secondary stage fine-tunes this pressure to the final output (e.g., 50 PSI). This staged process is essential for overcoming the phenomenon of "supply pressure effect" (where output pressure changes as input pressure drops) in high-ratio reduction systems, ensuring a consistent outlet pressure regardless of whether the cylinder is at 2200 PSI or 500 PSI. The internal valve components utilize specialized polymeric seats (e.g., PTFE or Kel-F) chosen for their compatibility with oxygen (non-flammability) and their low coefficient of friction, which minimizes the heat generated during the rapid adiabatic expansion of the high-pressure gas.
Note: The 803440-15 Oxygen Regulator is a life-support, TSO component and must be handled as such. Never use oil, grease, or any hydrocarbon-based sealant on the regulator or its connections, as this creates a severe fire/explosion hazard (auto-ignition due to adiabatic compression). The regulator is subject to mandatory overhaul intervals specified in the Component Maintenance Manual (CMM). Installation and functional pressure testing must be performed and certified by a licensed A&P mechanic in strict accordance with the CMM and the aircraft's Maintenance Manual.
Documentation
Authoritative documentation for this TSO component includes:
Avox Systems (Safran) Component Maintenance Manual (CMM) for Regulator Assembly 803440 Series.
FAA Technical Standard Order (TSO) C64 or applicable TSO.
Consult the aircraft's Maintenance Manual for system-specific installation requirements.