MSA A-ULTX-SENS-31-1-0 Combustible Gas Sensor

MSA A-ULTX-SENS-31-1-0 Combustible Gas Sensor Module (0–100% LEL)

The MSA A-ULTX-SENS-31-1-0 is a catalytic-bead smart sensor module engineered for continuous monitoring of combustible gases (Natural Gas, Methane, and Hydrogen) within the range of 0 to 100% Lower Explosive Limit (LEL). Machined from electropolished 316 stainless steel and utilizing fine mechanical mounting threads, this “Series 1” sensor assembly integrates advanced onboard temperature and humidity compensation circuitry.

Designed for native integration into MSA Ultima® XE, Ultima® XA, and Ultima® X3 fixed gas transmitters, it features MSA’s patented SafeSwap® hot-swappable interface. Marine systems engineers, instrumentation technicians, and offshore safety personnel can interchange or replace this sensor directly inside Class I, Division 1 / Zone 1 hazardous environments without declassifying the space or disconnecting transmitter loop power.

Model Details:

• Manufacturer: MSA
• Part Number (MPN): A-ULTX-SENS-31-1-0
• Internal SKU / Part Reference: AULTXSENS3110 / 10043818 series base architecture
• Sensing Principle: Matched-pair pellistor / Catalytic Bead (DuraSource™ active element)
• Measurement Scale: 0 to 100% LEL

Key Features

1. SafeSwap® Hot-Swap Capability: Enables complete sensor extraction and replacement under active 24V DC loop power without hot-work permits or atmospheric declassification.
2. DuraSource™ Catalytic Technology: Features an upgraded catalytic bead chemistry optimized for poison resistance against common industrial airborne silicones, sulfur compounds, and lead vapors.
3. Onboard Smart EEPROM Electronics: Retains factory calibration curves, span history, baseline drift offsets, and operating parameters directly inside the sensor head; auto-configures upon insertion into any Ultima X transmitter.
4. Marine & Offshore Survivability: Built with 316 stainless steel metallurgy to resist saline-induced chloride pitting, heavy offshore washdown, and severe ambient vibration.

Compatible Base Units

• MSA Ultima® XE: Explosion-proof 316 Stainless Steel transmitter.
• MSA Ultima® XA: General-purpose / water-resistant Polycarbonate transmitter.
• MSA Ultima® X3: Multi-channel digital network monitor (supports up to three multi-dropped sensors on Modbus RTU / RS-485 architecture).
• MSA Ultima® XIR (Conversion/Alternative Configurations): Used across combustible-gas monitoring segments where catalytic monitoring is mandated over non-IR detectable gases.

Part Number Cross-References:

• MSA Part No.: A-ULTX-SENS-31-1-0
• Model Descriptor: AULTXSENS3110
• Series Equivalent: Ultima X Series Gas Sensor, 0-100% LEL Natural Gas & H2

Applications

• Marine Machinery Spaces & Purifier Rooms: Continuous monitoring for light hydrocarbon leakage, marine diesel oil (MDO) atomization mist, and fuel-valve leaks.
• LNG / Dual-Fuel Carrier Bilges & Compressors: Rapid alerting against methane boil-off gas accumulation in enclosed pipe ducts and gas valve units (GVUs).
• Marine Battery Rooms & ESS Compartments: Detection of hydrogen off-gassing during high-rate charging cycles on lead-acid and lithium battery storage systems.
• Offshore Drilling & Production Platforms (FPSO / Topsides): Wellhead area monitoring, gas turbine enclosures, and open-deck process skid safety.
• Petrochemical Refineries & Tank Farms: Continuous LEL leak detection around pump seals, fractionation towers, and bulk transfer loading racks.

Frequently Asked Questions

What is the difference between MSA sensor code 31-1-0 and other Ultima X combustible sensors?

Code “31” designates the sensor’s calibration and response characteristics for Natural Gas (Methane) and Hydrogen across a 0–100% LEL span. The “-1-0” specifies the “Series 1” enhanced thermal and humidity compensation circuit encased in 316 stainless steel with fine-pitch mounting threads. Other codes denote solvents, petroleum vapors, or different mounting thread pitches.

Can I replace the A-ULTX-SENS-31-1-0 while the transmitter is running?

Yes. The sensor uses MSA’s patented SafeSwap design, which isolates power and prevents sparking during removal. You can unscrew and pull the sensor module out in an active hazardous area without isolating transmitter power or obtaining a hot-work permit.

How often does this catalytic sensor require calibration on a commercial vessel?

Industry and classification society standards (e.g., SOLAS, ABS, DNV) recommend bump testing every 30 days and full span calibration every 90 days. In environments with zero airborne contaminants or poisons, calibration intervals can be extended based on logged baseline stability.