Introduction
A sulfur dioxide gas sensor is a gas sensor used to detect and to measure the concentration of the sulfur dioxide (SO2) in the air or in the gases, and it is used in the environmental monitoring, the industrial safety, the process control, and the many other applications. The sulfur dioxide gas sensor operates by the various principles, including the electrochemical, in which the sulfur dioxide reacts at the electrodes and produces an electrical signal that is proportional to the concentration; the non-dispersive infrared (NDIR), in which the absorption of the infrared light by the sulfur dioxide is measured; and the other principles, and the sensor provides an electrical signal that is processed and displayed by the instrument; the sulfur dioxide gas sensor is used for the monitoring of the sulfur dioxide emissions from the industrial processes, for the monitoring of the ambient air quality, for the detection of the sulfur dioxide leaks, for the monitoring of the workplace safety, for the process control in the chemical and the power industries, for the monitoring of the combustion, and for many other applications, and it is available in various configurations, from the discrete sensors to the sensor modules and the gas detectors, with features such as the calibration and the temperature compensation; the sulfur dioxide gas sensor is an essential component for the sulfur dioxide monitoring. Sulfur dioxide gas sensors are used in the environmental monitoring, in the power plants, in the chemical industry, in the metallurgical industry, and for many other applications. With their sulfur dioxide detection, sulfur dioxide gas sensors are essential for the SO2 monitoring.
IR Carbon And Sulphur Analyzer LCSA-T2011
IR Carbon And Sulfur Analyzer includes five infrared detection pools, expanding its sulfur measurement range from 0.1 to 60%. It ensures precise readings with a carbon detection range of...
IR Carbon And Sulphur Analyzer LCSA-T2010
IR Carbon and Sulfur Analyzer features four independent infrared detection pools for accurate carbon and sulfur analysis. It measures carbon from 0.001 to 50% and sulfur from 0.00001 to ...
UV Fluorescence Sulfur Analyzer LST-T2014
UV Fluorescence Sulfur Analyzer provides a measuring range of 0.2 to 10000mg/L. Utilizes advanced ultraviolet lamp and key components to ensure exceptional sensitivity and operational re...
X-ray Fluorescence Sulfur Analyzer LST-T2013
X-ray Fluorescence Sulfur Analyzer provides a total sulfur measuring range within 7ppm to 5%. It utilizes computerized quantitative analysis based on the principle of X-ray fluorescence ...
XRF Oil Analyzer LXOA-T2010
Oil Analyzer measures sulfur content in oil, additives, and other fluids to help monitor quality. It has a fully enclosed X-ray chamber that protects users from radiation and prevents c...
XRF Sulfur/Chlorine Analyzer LXSC-T2010
Sulfur/Chlorine Analyzer measures sulfur (S) and chlorine (Cl) in various samples. It can detect element concentrations ranging from 0.5 ppm to 20%. The device is sensitive enough to de...
IR Carbon And Sulphur Analyzer LCSA-T2030
IR Carbon and Sulphur Analyzer measures carbon in the range of 0.00002% to 10% and sulfur from 0.00002% to 5%. With a detector sensitivity of 0.01 ppm, it ensures accurate trace-level de...
IR Carbon And Sulfur Analyzer LCSA-T2021
IR Carbon And Sulfur Analyzer includes three detector sets for high-carbon, low-sulfur, and carbon monoxide analysis. It measures carbon up to 20% and sulfur up to 5%, with expandable ra...
IR Carbon And Sulphur Analyzer LCSA-T2020
IR Carbon And Sulfur Analyzer has two sets of detectors for high-carbon and low-sulfur analysis, ensuring reliable measurement. It measures carbon from 0.0001 to 20% and sulfur from 0.00...
Total Sulfur Analyzer LTSA-T2010
Total Sulfur Analyzer measures total sulfur content in 5 µL to 50 µL sample. It is equipped with advanced ultraviolet fluorescence for correct measurement, improving efficiency. Integr...
IR Carbon and Sulphur Analyzer LCSA-T2011
IR Carbon and Sulphur Analyzer is a high-frequency infrared analyzer for carbon (0.0001% to 10%) and sulfur (0.0001% to 3.5%) with fast 35-second analysis. Its detection unit features a ...
Portable Infrared Gas Detector LIGD-T2010
Portable infrared gas detector is a hand-held SF6 (sulfur hexafluoride) Gas detector for continuous measurement of gas. Adopted with imported gas infrared sensor, it utilizes unique meth...
Mercaptan Sulfur Tester LMST-T2010
Mercaptan Sulfur Tester determines mercaptan sulfur content present in petroleum products with help of the computer. This detection method is based on principle of Potentiometric titrati...
X-ray Fluorescence Sulfur in Oil Analyzer LST-T2010
X-ray Fluorescence Sulfur in Oil Analyzer offers wide measurement range 0.0050%–5% with 10 ppm detection limit. Employs fluorescence intensity ratio method with automatic correction adj...
Sulfur Dioxide Gas Sensor LSGS-T2010
Sulfur dioxide gas sensor offers a flexible measurement range of 0 to 1000 ppm or 0 to 5000 ppm, making it suitable for various monitoring needs. It uses advanced semiconductor sensor te...
Fluorescence Sulfur Analyzer T-FSA-4020
XRF Sulfur in Oil Analyzer T-SOA-S2100
Portable Sulfur Dioxide Gas Detector T-SGD-S2101
Sulfur Dioxide Gas Detector T-SDD-S2100
Carbon And Sulfur Analyzer T-CSA-S2100
Portable Trace Detector T-TDD-S2100
Portable Sulfur Dioxide Gas Detector T-SGD-S2100
Portable Infrared Gas Detector T-IGD-S2100
Sulfur Analyzer T-SA-4010
Carbon And Sulfur Analyzer T-S211CSA
Carbon and Sulfur Analyzer features an extensive measurement range, detecting carbon from 0.0005 to 6% and sulfur from 0.0005 to 0.5000%. It utilizes a high-frequency induction furnace, e...
Dark Petroleum Sulphur Content Tester T-S210DST
Dark petroleum sulphur content tester is a microprocessor-controlled unit with the tubular oven method. The characteristic heating and sample analysis at high temperature is carried out a...
Carbon and Sulfur Analyzer T-S210CSA
Carbon and Sulfur Analyzer utilizes a high-frequency induction combustion furnace for precise determination. It has multi-level concealed isolation circuit to completely solve high-freque...
XRF Sulfur and Lead Analyzer T-S210XSL
XRF Sulfur and Lead Analyzer is capable of detecting lead with an LOD of 2.5 ppm and sulfur with an LOD of 5 ppm. It features a Silicon Drift Detector with a resolution of 130eV for high ...
Sulfur dioxide Detector T-S210SDD
Sulfur dioxide detector is a portable unit that provides highly sensitive and accurate measurement. High/Low alarm function with three alarm methods. Digital LCD display with backlight fu...
Sulfur hexafluoride Detector T-S210SHF
Sulfur hexafluoride detector is a hand held unit with 5 hours’ continuous operation time. It features overcharge and over current protection.
Applications
Used in industry and can be fou...
Sulfur Content Tester (Quartz-Tube method) T-S211SCT
Sulfur content tester (Quartz-Tube method) is a two tube automated unit. The system provides extensive function of setting experimental time to suit all test requirements. Conforms to AST...
Sulfur Content Tester (Lamp Method) T-S210SCT
Sulfur content tester (Lamp Method) is a desktop unit with vacuum pump adjustment. Equipped with five tubes and organic glass pane, ensures reliable operation. Conforms to ASTM D1266 stan...
Mercaptan Sulfur Content Tester T-S211MSC
Mercaptan sulfur content tester is a fully automated unit with windows operating system. The system includes high quality titration unit ensuring accuracy and stability. Conforms to ASTM ...
Mercaptan Sulfur Content Tester T-S210MSC
Mercaptan sulfur content tester is a microprocessor controlled unit. Automated metering pumps ensure accuracy of titration results. It is designed conforming ASTM D3227-13 international s...
Standards
ISO 6143:2001-Gas analysis-Comparison methods for determining and checking the composition of calibration gas mixtures
Complies with the above standards, but is not limited to them.
Features
1. Sulfur dioxide (SO2) gas sensor for detection and monitoring of sulfur dioxide in air.
2. Electrochemical or NDIR SO2 sensor with digital output, designed for industrial safety and environmental monitoring.
3. Suitable for industrial hygiene, environmental monitoring, chemical plants, power plants, food processing and indoor air quality.
4. Includes sensor module, housing, cable/connector, calibration certificate and operation manual.
5. Supports SO2 concentration measurement (ppm) with fast response, high selectivity and long-term stability.
FAQ
Q1: What testing scenarios is this sensor mainly applied to?
A: The sulfur dioxide (SO2) gas sensor is used in industrial hygiene, environmental monitoring, chemical plants, power plants, food processing, and indoor air quality for detection and continuous monitoring of sulfur dioxide gas in air, providing early warning of SO2 exposure (toxic, irritant) and emissions monitoring. It supports industrial hygiene and worker safety (chemical plants (SO2 is used/produced in sulfuric acid manufacturing, sulfite processing, paper pulping (Kraft process), smelting (copper, lead, zinc - SO2 is byproduct of sulfide ore roasting), refineries, fertilizer plants - monitor worker exposure (OSHA PEL 5 ppm TWA, 2 ppm STEL; ACGIH TLV 2 ppm TWA; NIOSH REL 2 ppm), fixed gas detection systems, personal gas monitors), environmental and emissions monitoring (power plants (coal-fired power plants emit SO2 (major source of acid rain); continuous emissions monitoring systems (CEMS) for SO2 per EPA regulations; flue gas desulfurization (FGD) efficiency monitoring), industrial boilers, smelters, refineries - stack emissions monitoring, ambient air quality monitoring (SO2 is criteria air pollutant per EPA NAAQS; urban/industrial area monitoring), food and beverage (SO2 is used as preservative (sulfites) in wine, dried fruit, juice, processed foods - monitor SO2 levels in food processing areas (worker exposure), wine production (SO2 additions, barrel storage areas; sulfite allergy concerns), indoor air quality (commercial buildings, schools, offices near industrial sources; SO2 irritates respiratory system, triggers asthma), mining and metallurgy (underground mines (sulfide ore oxidation can produce SO2), smelters, mineral processing), and emergency response (HazMat, fire service - detect SO2 at chemical spills, fires (sulfur-containing materials), industrial accidents). SO2 properties: Colorless gas with pungent, irritating odor (rotten match smell at low concentrations; odor threshold ~0.3-1 ppm). Heavier than air (2.3x air). Toxic: irritates eyes, nose, throat, respiratory tract; high concentrations cause bronchoconstriction, pulmonary edema; can be fatal at high levels (>100 ppm). Reacts with water/moisture to form sulfurous acid (corrosive). Major pollutant contributing to acid rain and particulate matter (sulfate). Sensor types: (1) Electrochemical (most common for SO2): gas diffuses through membrane, reacts at working electrode, produces current proportional to concentration. Range 0-20/50/100/500 ppm, resolution 0.1-1 ppm, fast response (30-60 sec), selective (with filters for cross-sensitivity), lifespan 1-3 years. (2) NDIR (non-dispersive infrared): SO2 absorbs IR at specific wavelength; more expensive, longer life (5+ years), better for high concentrations (0-5000 ppm), less cross-sensitivity. (3) PID (photoionization): not ideal for SO2 (high ionization energy). This is a sensor/module (not a complete gas detector) - FAQ focuses on sensor use, calibration, maintenance, safety. See 3263 (gas sensor) for general gas sensor concepts.
Q2: What standards does the sensor comply with?
A: The sulfur dioxide gas sensor follows relevant ISO, IEC, OSHA, EPA and GB/T standards including IEC 60079 (explosive atmospheres - if ATEX/IECEx certified for hazardous locations), ISO 15004 (gas detectors - performance requirements), EN 45544 (electrochemical gas detectors for toxic gases), OSHA (Occupational Safety and Health Administration - PEL 5 ppm TWA, 2 ppm STEL), ACGIH (TLV 2 ppm TWA), NIOSH (REL 2 ppm TWA, 5 ppm STEL, IDLH 100 ppm), EPA (SO2 as criteria pollutant - NAAQS primary 1-hour 75 ppb, annual 0.03 ppm; CEMS requirements per 40 CFR Part 60/75), and GB/T standards for gas sensors and SO2 monitoring. The hardware complies with applicable sensor performance (accuracy +/- 5-10% full scale or +/- 2 ppm, response time T90 <30-60 sec, repeatability, cross-sensitivity specs), EMC (IEC 61326), and safety (ATEX/IECEx for hazardous locations (Zone 0/1/2), intrinsic safety). For industrial hygiene, follow OSHA regulations (29 CFR 1910.1000 - air contaminants; 1910.146 - permit-required confined spaces). For emissions monitoring, follow EPA performance specifications (PS-2 for SO2 CEMS) and 40 CFR Part 60/75. For food processing, follow FDA regulations (SO2 as preservative - 21 CFR; sulfite labeling >10 ppm). For indoor air, follow ASHRAE/EPA guidelines. For hazardous locations (chemical plants, refineries), sensor must be ATEX/IECEx/CSA certified for appropriate gas group and zone. For regulated monitoring, maintain calibration records (calibration gas certificates traceable to NIST/PTB/NIM, as-found/as-left data, sensor ID, calibration due date).
Q3: What is the warranty period for the whole sensor and key components?
A: The whole SO2 sensor is covered by a 12-24 month warranty (industrial sensors often 1-2 years; electrochemical sensor life is 1-3 years). The sensor element, housing, electronics, and cable are covered, while the electrochemical sensor cell (wear part - lifespan 1-3 years depending on exposure (high SO2 concentrations shorten life; storage in air with zero SO2 extends life; drying out damages), calibration gas (consumable), and filters/membranes (wear - can clog/age) are consumables/accessories. Damage from improper use, exposure to high concentrations beyond range (sensor poisoning/overload - can permanently damage electrochemical cell), exposure to interfering gases (high H2S, NO2, Cl2 can cross-sensitize or poison), drying out (electrochemical sensors need humid environment; dry gas/desiccant can damage electrolyte), extreme temperatures (outside operating range - damages electrolyte/electronics), liquid ingress (condensation, water in sensor housing), or unauthorized repair is excluded. Extended warranty and service contracts (calibration, sensor replacement) may be available. Electrochemical sensor lifespan: 1-3 years (typical 2 years in normal use; high exposure or dry conditions shorten); NDIR sensor lifespan: 5+ years (longer, but more expensive). Calibration recommended every 1-6 months (more frequent for safety-critical applications).
Q4: Is this device difficult to operate? Is professional training required?
A: Operation (as a sensor module) requires integration into a gas detector or monitoring system by qualified personnel (instrument technicians, EHS engineers). We provide operation manuals and technical support. For end-users (reading gas detector): simple (display shows concentration, alarms). Proper sensor use (installation: mount sensor in appropriate location (near breathing zone for worker safety, near potential leak sources (valves, pumps, tanks), at appropriate height (SO2 is heavier than air - mount near floor/low points for leak detection; for worker exposure, mount at breathing zone (1.5 m)), ensure proper ventilation (sensor needs gas to reach it; avoid dead zones, high airflow areas that dilute), avoid direct water spray/condensation (use weatherproof housing, splash guard), connect to controller/data logger (4-20 mA, Modbus, digital output - verify wiring, address, scaling), calibration: before first use and periodically (bump test daily/weekly for safety-critical (expose to known gas, verify response/alarm; if fails, full calibration), full calibration every 1-6 months with certified SO2 calibration gas (e.g., 10 ppm or 50 ppm in nitrogen, traceable), zero calibration (in clean air or zero gas), span calibration (with known concentration), record calibration (date, gas concentration, as-found/as-left, operator, sensor ID), operation: monitor readings (normal background should be near 0 ppm in clean air; if >0, investigate), alarms (set low alarm (e.g., 2 ppm = TLV/TWA), high alarm (e.g., 5 ppm = STEL/PEL), or per site safety plan), respond to alarms (evacuate, ventilate, investigate source, use PPE/SCBA for high concentrations), maintenance: inspect sensor (housing, cable, connections - no damage, corrosion), check filter/membrane (clean or replace if clogged/damaged), verify calibration due date, replace sensor when expired or failing (slow response, unstable zero, cannot calibrate), troubleshooting (no reading / sensor dead (sensor expired (replace), cable/connection loose (check), power issue (check), electronics fault (service), reading unstable / noisy (airflow turbulence (relocate), condensation (dry/weatherproof), sensor aging (replace), calibration drift (recalibrate), high readings / false alarm (cross-sensitivity (other gases: H2S, NO, NO2, CO, Cl2 can interfere; check for other gas sources; use filtered sensor or multi-gas detector), calibration error (recalibrate), sensor poisoning (replace), zero drift (recalibrate zero), low readings / no response (sensor poisoned/overloaded (exposed to high SO2 - replace), calibration gas wrong (verify), blocked filter/membrane (clean/replace), cable fault (check), and safety (SO2 TOXICITY (SO2 is toxic and irritating: 1-5 ppm = odor, mild irritation; 5-10 ppm = eye/nose/throat irritation, cough; 20-50 ppm = severe irritation, bronchoconstriction (danger for asthmatics); 100+ ppm = life-threatening (pulmonary edema, can be fatal); IDLH = 100 ppm; OSHA PEL = 5 ppm TWA, 2 ppm STEL; ACGIH TLV = 2 ppm TWA; ALWAYS take alarms seriously; evacuate at high readings; use SCBA/respirator for entry into high SO2 areas), SENSOR INSTALLATION (SO2 is heavier than air (2.3x) - accumulates in low areas, pits, confined spaces; mount leak detection sensors low; for worker exposure, mount at breathing zone; confined space entry requires gas testing (OSHA 1910.146) with calibrated monitor), CALIBRATION (safety-critical sensors must be calibrated regularly; bump test before use in confined spaces; use certified calibration gas; do not use uncalibrated sensor for safety decisions), CROSS-SENSITIVITY (electrochemical SO2 sensors can respond to other gases (H2S, NO, NO2, CO, Cl2, ozone); if multiple gases present, use filtered sensor or multi-gas detector with separate sensors; NDIR has less cross-sensitivity), ENVIRONMENT (electrochemical sensors have operating temp range (typically -20 to 50 C) and humidity range (15-90% RH non-condensing); extreme dryness damages electrolyte; condensation can short sensor; use weatherproof housing with Gore-Tex membrane), do not expose sensor to concentrations beyond range (can permanently damage electrochemical cell; if overexposed, replace and recalibrate), do not use sensor for personal safety if not calibrated or certified (use only gas detectors with appropriate certifications (ATEX, IECEx, CSA) for hazardous locations), for food processing: SO2 is used as preservative but sulfites can cause allergic reactions (asthma); monitor worker exposure and food residue levels, for emissions (CEMS): follow EPA QA/QC requirements (daily calibration checks, quarterly audits, annual relative accuracy test audit (RATA)), dispose of used electrochemical sensors properly (contain electrolyte/heavy metals - hazardous waste per regulations), do not open sensor housing (contains electrolyte; can irritate skin/eyes; replace as unit) are critical for safe SO2 sensor use.
Q5: What is the typical lead-time for order delivery?
A: Standard models require 7-30 working days. In-stock units can ship within 3-7 working days. Custom configurations or large built-to-order systems may require additional time, and we confirm the exact schedule before order confirmation.
Q6: Is regular calibration required? What is the recommended calibration cycle?
A: Calibration is REQUIRED for gas safety sensors: bump test (functional test with known gas) before each use or daily/weekly for safety-critical/fixed systems (verify sensor responds and alarms trigger; if bump test fails, full calibration required); full calibration (zero + span) every 1-6 months depending on application (industrial safety: monthly to quarterly; emissions CEMS: daily calibration checks + quarterly/annual; indoor air: every 6-12 months). If sensor is replaced, exposed to high concentration, dropped, or readings seem off, recalibrate immediately. Calibration gas: certified SO2 in nitrogen (e.g., 10 ppm, 25 ppm, 50 ppm, or 100 ppm), traceable to NIST/PTB/NIM, within expiration date. Zero: clean air (SO2-free) or zero gas. Span: known concentration (typically 50-80% of full scale). For ISO 17025/OSHA/EPA regulated applications, follow applicable schedules and maintain records (calibration certificates, gas lot/expiry, as-found/as-left data, sensor ID, calibration due date, operator). For confined space entry (OSHA 1910.146): bump test before each entry. For CEMS (EPA): daily zero/span checks, quarterly audits, annual RATA. Sensor replacement: when calibration fails (cannot reach span, slow response T90 >60-90 sec, unstable zero), or at end of life (1-3 years electrochemical, 5+ years NDIR). Keep calibration records for regulatory compliance and safety audits.
Q7: Are supporting consumables universal?
A: Calibration gas (SO2 in nitrogen, certified - universal from gas suppliers (Airgas, Praxair, Linde) but must be correct concentration and certified traceable; use within expiration), sensor replacement (specific to detector brand/model - use OEM or certified compatible sensor), filters/membranes (specific to sensor housing - use OEM), and calibration accessories (regulator, tubing, flow meter - universal gas detection accessories) are available from industrial safety/gas supply companies, though sensors and filters are brand-specific (use OEM or certified compatible to maintain accuracy, certifications, and warranty). Long-term consumable cost includes calibration gas (regular, $50-$200 per cylinder), sensor replacement (every 1-3 years, $100-$500 for electrochemical, $500-$2000 for NDIR), and filters (periodic). For fixed systems, calibration gas and sensor replacement are ongoing costs.
Q8: Can I customize parameters or supporting accessories?
A: Customization includes sensor type (electrochemical (most common, 0-20/50/100/500 ppm, low cost, fast response, 1-3 year life) or NDIR (non-dispersive infrared, 0-500/5000 ppm, longer life 5+ years, less cross-sensitivity, higher cost, for high concentrations/emissions)), range (0-5 ppm (low, for indoor/ambient), 0-20 ppm (industrial hygiene TLV), 0-50/100 ppm (general industrial), 0-500/5000 ppm (emissions, high concentration)), output (4-20 mA analog (standard, easy integration), Modbus RS485/RTU (digital, multi-drop), HART, CANopen, or proprietary digital), housing (IP65/66/67 (weatherproof), explosion-proof/intrinsically safe (ATEX/IECEx/CSA for Zone 0/1/2, Group IIC), stainless steel or aluminum), cable length (1-30 m, with connector), features (built-in temperature compensation, humidity compensation, cross-sensitivity filters, fast response (T90 <30 sec), low drift, long life), accessories (calibration gas (cylinder, regulator, tubing), calibration cap/adapter, weatherproof housing, splash guard, mounting bracket, junction box, data logger/controller, spare sensor, filter kit, calibration certificate (ISO 17025), certifications (ATEX, IECEx, CSA, SIL 2, CE, ISO 9001), language and accessories. Additional sensors, calibration gas, and accessories can be ordered separately.
Q9: Does the purchase include on-site installation and commissioning service?
A: Standard delivery includes SO2 sensor module, housing, cable/connector, calibration certificate (initial), and instruction manual. On-site installation, configuration, and calibration ARE typically required for fixed gas detection systems (sensor must be mounted, wired to controller, configured (address, scaling, alarms), and calibrated by qualified technician; for safety-critical applications, professional installation by certified gas detection technician is standard and may be required by code/insurance). For personal/portable gas monitors: sensor replacement by user is feasible (follow manual), but calibration should be done with proper equipment. Always calibrate with certified gas before first use and maintain calibration schedule. For ATEX/IECEx installations, must be done by competent person per hazardous area regulations.
Q10: What types of samples/environments are compatible with this equipment?
A: The SO2 gas sensor detects sulfur dioxide in air/gas streams including industrial environments (chemical plants, sulfuric acid plants, smelters, refineries, paper mills, fertilizer plants), power plants (coal-fired, flue gas), food processing (wine, dried fruit, juice - SO2 preservative areas), indoor air (commercial buildings, schools near industrial sources), confined spaces (tanks, pits, vessels - SO2 accumulates low), and ambient air (environmental monitoring, urban/industrial areas). NOT compatible with: Liquids (sensor is for gas only; condensation/liquid ingress damages sensor - use weatherproof housing), high concentrations beyond sensor range (can damage electrochemical cell; use appropriate range or NDIR for high), environments with high interfering gases (H2S, NO2, Cl2, CO, ozone can cause cross-sensitivity with electrochemical sensors - use filtered sensor or NDIR; if multiple gases, use multi-gas detector), extreme temperatures outside operating range (typically -20 to 50 C; high heat damages electrolyte; freezing can damage), extreme dryness (<15% RH - dries electrochemical sensor electrolyte; use humidified or NDIR), high particulate/dust (clogs filter/membrane - use filter, clean regularly), flammable/explosive atmospheres without proper certification (use ATEX/IECEx/CSA certified sensor for hazardous locations), and vacuum/pressurized systems beyond sensor rating (most sensors are for atmospheric pressure; for pressurized ducts (CEMS), use extractive system with conditioning). For flue gas/emissions: gas is hot, dusty, moist, high CO2/NOx - requires sample conditioning (cooling, drying, filtering) before sensor; use NDIR or extractive CEMS, not raw electrochemical sensor. For confined spaces: test before entry (OSHA 1910.146), use calibrated personal monitor, SO2 is heavier than air (test low areas). For food areas: monitor worker exposure, not food product (SO2 in food is measured by chemical methods, not gas sensor). IMPORTANT: Sulfur dioxide (SO2) gas sensor fundamentals: (1) What is SO2? Colorless, toxic gas with pungent odor (burning match). Heavier than air. Major air pollutant (acid rain, particulate matter). Used in chemical industry, food preservative, wine. (2) Health effects: - 0.3-1 ppm: odor threshold. - 1-5 ppm: mild eye/nose/throat irritation. - 5-10 ppm: irritation, cough (OSHA PEL 5 ppm TWA, 2 ppm STEL; ACGIH TLV 2 ppm). - 20-50 ppm: severe irritation, bronchoconstriction (danger for asthmatics). - 100+ ppm: life-threatening (pulmonary edema); IDLH = 100 ppm. (3) Sensor types: - Electrochemical (most common): Gas diffuses through membrane, electrochemical reaction at electrode produces current proportional to concentration. Range 0-500 ppm, fast, cheap, 1-3 year life. Cross-sensitive to other gases. - NDIR: Infrared absorption. Range 0-5000 ppm, longer life (5+ years), less cross-sensitivity, expensive. For emissions/high concentration. (4) Key parameters: - Range: 0-20 ppm (hygiene), 0-100 ppm (general), 0-5000 ppm (emissions). - Response time T90: <30-60 sec. - Accuracy: +/- 5-10% FS or +/- 2 ppm. - Operating temp: -20 to 50 C. - Life: 1-3 years (electrochemical), 5+ years (NDIR). (5) Calibration: - Bump test: before use (safety). - Full calibration: monthly-quarterly (safety), daily (CEMS). - Zero: clean air. - Span: certified SO2 gas (50-80% FS). (6) Safety: - SO2 is toxic - take alarms seriously. - Heavier than air - low-point monitoring. - Confined space testing required. - Use SCBA for high concentrations. - ATEX/IECEx for hazardous areas. (7) Common errors: - Not calibrating (safety risk). - Cross-sensitivity (false readings from H2S, NO2). - Sensor expired (slow/no response). - Condensation/liquid damage. - Wrong mounting location (too high for heavy gas, dead zone). - Using electrochemical for high concentration/emissions (use NDIR). (8) Choosing the right sensor: - Worker safety (0-20/50 ppm): Electrochemical, ATEX certified. - Emissions/CEMS (0-5000 ppm): NDIR or extractive system. - Indoor/ambient (low ppb): Specialized low-range sensor or reference method. - Hazardous location: ATEX/IECEx/CSA certified. - High interfering gases: NDIR or filtered electrochemical.
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