High-Quality NOx Gas Analyzer Suppliers & Factory

In typical fossil combustion flue streams (coal, gas, oil), nitric oxide (NO) accounts for approximately 90% to 95% of total nitrogen oxides generated, while nitrogen dioxide (NO₂) comprises the remaining 5% to 10%. However, environmental agencies enforce discharge limits based on total NOx expressed as equivalent NO₂ mass (mg/m³ or ppm). When using single-channel NDIR or standard Chemiluminescence (CLD), the sample must pass through a high-efficiency NO₂-to-NO thermal converter (such as Shield’s 350°C molybdenum converter) to convert all NO₂ into NO prior to detection. Alternatively, Shield’s UV-DOAS technology directly measures the unique absorption bands of both NO and NO₂ simultaneously across the ultraviolet spectrum, eliminating the maintenance, electrical consumption, and failure risks of external converter units.

Moisture poses two distinct challenges: physical chemical absorption and spectral optical interference. First, nitrogen dioxide (NO₂) is water-soluble; if moisture condenses inside unheated sampling lines or standard moisture separators, NO₂ dissolves into the water droplets, forming nitric/nitrous acid and causing massive false-low concentration readings (up to 30% signal loss). Shield addresses this via heated lines (180°C) and flash-condensation Peltier coolers with ultra-low gas contact residence time (< 0.5s). Second, in infrared (NDIR) systems, water vapor molecules have broad absorption spectra that overlap the NO absorption spectrum. Shield utilizes UV-DOAS or dual-wavelength differential filtering where water vapor has zero absorption, ensuring drift-free baseline stability even in saturated wet scrubbed flue gas environments.

Yes. A primary differentiator of Sichuan Shield Technology is our unified gas safety chain. Both our point-type industrial detectors (SD2130 series) and multi-channel control consoles (SD8001 series) feature dedicated dry-contact relay outputs (normally open / normally closed rated up to 5A 250V AC) and pulsed DC solenoid driver outputs. Upon reaching a pre-programmed alarm setpoint (e.g., 20% LEL or dangerous toxic thresholds), the instrument instantly trips the aluminum alloy emergency shut-off valve (such as the JYFJS-011) in under 1 second. Shield shut-off valves feature a manual reset latch mechanism, ensuring that pipeline gas flow cannot resume until safety personnel physically inspect the hazard area and clear the condition.

For continuous emission monitoring installations governed by EPA 40 CFR 60/75 or EN 14181 QAL3 standards, Shield instruments incorporate fully automated zero/span calibration solenoids. We recommend a daily automated zero check using dry scrubbed instrument air or high-purity nitrogen (99.999%), an automated single-point span check every 7 to 14 days using certified span calibration gas, and a quarterly manual linearity verification across four concentration steps. Because our UV-DOAS and high-end NDIR optical chambers feature zero moving parts and temperature-stabilized detectors, physical calibration adjustments are seldom required, keeping annual technician maintenance hours under 12 hours per monitoring shelter.

As a direct high-tech manufacturer with in-house automated SMT lines and CNC optical machining in Chengdu, Shield maintains standard sensor platforms in stock. For standard catalog models (SD2100, SD2130, BTYQ-Z4), typical sample orders ship within 3 to 5 business days, while volume distributor shipments (100–500 units) require 15 to 20 days. Minimum Order Quantities (MOQ) for custom private-label branding (housing colors, custom metal front panels, branded firmware GUI, and customized protocol mapping) start as low as 50 units. All shipments include traceable factory calibration certificates, explosion-proof documentation, and comprehensive English technical manuals.