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Overview
Sulphur dioxide is a gas that appears across a surprisingly wide range of industrial operations — from smelting and refinery processes to winemaking, food preservation, paper manufacturing, and maritime cargo handling. It is colourless, heavier than air, and has a sharp, pungent odour that provides some natural warning at low concentrations. But relying on smell alone is not a safety programme. SO2 causes immediate respiratory irritation at concentrations above 2 ppm, and at higher concentrations it is capable of causing serious lung injury. For workplaces where sulphur dioxide is present, gas detectors need to be accurately calibrated — and kept in calibration — to provide a reliable early warning before concentrations reach harmful levels.
The SO2 Sulphur Dioxide Balance Nitrogen Calibration Gas (5 / 10 / 50 ppm) is a range of precision-formulated span gas cylinders for the calibration of electrochemical sulphur dioxide gas detectors across three concentration levels. The 5 ppm, 10 ppm, and 50 ppm concentration options cover the full range of SO2 detector alarm configurations — from low-level TWA-referenced occupational exposure limit calibration through to higher-range process and industrial hygiene monitoring thresholds. Nitrogen (N2) is used as the balance gas, providing an inert, oxygen-free carrier that preserves the certified SO2 concentration throughout the cylinder’s service life and eliminates atmospheric interference during calibration.
Supplied by Alright Engineering Solutions as part of their span gas and regulator range, this calibration gas is available in C10 aluminium cylinders from 34 litres to 116 litres — suitable for portable single-instrument field calibration through to fixed calibration stations serving multi-detector maintenance programmes. For HSE managers, instrument technicians, and procurement teams operating in smelting, refining, pulp and paper, food processing, maritime, and chemical industries, this product provides the certified SO2 reference gas that accurate detector calibration requires.
Key Features
Three Calibration Concentrations — 5 ppm, 10 ppm, and 50 ppm
Sulphur dioxide detectors across different industries are configured to alarm at different thresholds depending on the applicable occupational exposure limits and the severity of the SO2 exposure risk at the specific site. The 5 ppm concentration supports calibration of detectors set to alarm near the ACGIH TLV-TWA of 0.25 ppm or OSHA PEL of 5 ppm TWA — appropriate for general workplace monitoring in chemical facilities, food processing environments, and laboratories. The 10 ppm concentration suits mid-range STEL-referenced detector calibration. The 50 ppm concentration is suited to detectors configured for higher-range monitoring in smelting operations, sulphur recovery units, and industrial process areas where SO2 is generated in higher concentrations. Selecting the calibration gas concentration that aligns with your detector’s alarm setpoint is the correct approach to span calibration — and having all three concentrations available from a single local supplier simplifies procurement across a mixed detector estate with varying alarm configurations.
Nitrogen Balance Gas — Inert and Reactive-Gas-Free Carrier
Sulphur dioxide is a reactive acidic gas. In the presence of moisture or oxygen, it can oxidise to sulphur trioxide or form sulphurous acid — both of which would alter the effective calibration gas concentration and potentially damage electrochemical sensor components. Nitrogen provides an inert, completely dry, and oxygen-free balance gas that prevents any in-cylinder reaction with the SO2 component, preserving the certified concentration from first fill to last use. For electrochemical SO2 sensors, which can exhibit cross-sensitivity to hydrogen sulphide and nitrogen dioxide in certain sensor designs, a nitrogen balance also eliminates background atmospheric gas interference that could affect calibration accuracy in field conditions.
Multiple Cylinder Sizes — 34L to 116L
The C10 range covers five cylinder sizes: 34L, 58L, 103L, 110L, and 116L. The 34L and 58L options are well suited to portable calibration kits, vessel maintenance programmes, and single-instrument calibration tasks where the technician needs to transport the cylinder to the detector location. The 103L to 116L sizes are appropriate for fixed calibration stations, high-frequency calibration schedules, and fleet maintenance programmes where multiple SO2 detectors are calibrated on a regular basis — delivering a meaningfully lower cost per calibration event and reducing the frequency of cylinder procurement and changeout in active maintenance programmes.
Certified Concentration with Traceable Accuracy
SO2 calibration gas for safety-critical detector maintenance must carry a certified concentration with traceability documentation to national or international measurement standards. The 5, 10, or 50 ppm certified concentration of this span gas provides the traceable calibration reference required for ISO 9001 quality management system records, ISO 45001 occupational health and safety management system documentation, and site-specific instrument calibration control procedures subject to audit. For operations in the smelting and refining sectors where SO2 exposure monitoring is subject to regulatory oversight, calibration performed against certified traceable span gas is the appropriate standard for a defensible calibration programme.
Aluminium Cylinder — Lightweight and Compatible with SO2 Service
Sulphur dioxide’s acidic reactivity makes cylinder material selection relevant to long-term concentration stability. Aluminium provides acceptable chemical compatibility for SO2 gas storage at the low ppm concentrations used in calibration applications — resisting the surface degradation that SO2 can cause to ferrous metal cylinder walls over time. The weight advantage of aluminium over steel is a practical benefit for technicians carrying calibration equipment across smelter floors, refinery process areas, vessel engine rooms, and other industrial environments where portability and ease of handling matter for the safe completion of calibration tasks.
Compatible with Standard SO2 Detector Calibration Regulators and Adapters
The cylinder valve configuration is compatible with standard calibration gas regulators and detector-specific calibration adapters for SO2-capable portable and fixed gas detector models from leading manufacturers including MSA, Industrial Scientific, Honeywell BW, Dräger, and others. As with all reactive gas calibration, confirming regulator and tubing material compatibility for SO2 service before use is recommended — Alright Engineering Solutions can advise on appropriate regulator and tubing specifications for your specific detector models and calibration workflow.
Technical Specifications
Product: SO2 Sulphur Dioxide Balance Nitrogen Calibration Gas
Gas Component: Sulphur Dioxide (SO₂)
Available Concentrations: 5 ppm / 10 ppm / 50 ppm
Balance Gas: Nitrogen (N2)
Cylinder Specification: C10
Available Cylinder Sizes: 34L / 58L / 103L / 110L / 116L
Cylinder Material: Aluminium
Product Category: Span Gas and Regulator
Supplied By: Alright Engineering Solutions Pte. Ltd.
Benefits
Verify detector response at the concentration that matters for your workers. Electrochemical SO2 sensors drift with age and can be affected by exposure to high SO2 concentrations, humidity cycling, and cross-sensitive gases including H₂S and NO₂. A sensor that has drifted low will under-read sulphur dioxide concentration — potentially failing to alarm before workers are exposed to levels that exceed the applicable occupational exposure limit. Regular span calibration with certified SO2 span gas at the concentration relevant to your detector’s alarm threshold is the practical check that confirms your detector is responding correctly to SO2 — and providing the early warning it was installed to give.
Maintain auditable calibration records for regulatory compliance. Smelting operations, petroleum refineries, and sulphur-handling facilities operate in regulatory environments where gas detector maintenance — including calibration against certified reference gas — is subject to specific regulatory requirements and may be reviewed during statutory inspections. Calibration records documenting that SO2 detectors were calibrated using certified span gas at the correct concentration provide the auditable evidence required to demonstrate compliance with detector maintenance obligations under applicable workplace safety legislation.
Match span gas concentration to your site’s specific alarm setpoints. Using a 50 ppm span gas to calibrate a detector configured to alarm at 5 ppm TWA introduces span error at the detection range most relevant to your workers’ exposure risk. The availability of 5 ppm, 10 ppm, and 50 ppm concentration options from a single supplier allows procurement teams and instrument technicians to select the calibration gas that aligns with each detector’s configured alarm threshold — improving calibration accuracy where it matters most.
Reduce per-calibration cost with larger cylinder formats for high-frequency programmes. For sites calibrating multiple SO2 detectors on a weekly or monthly schedule — such as smelters with extensive fixed detection networks or facilities with large portable detector fleets — the 103L to 116L cylinder options provide a significantly lower cost per calibration compared to small-format aerosol canisters, without any reduction in calibration quality or certified concentration accuracy.
Reliable local supply in Singapore across all three concentrations. Alright Engineering Solutions maintains SO2 span gas stock locally across the 5 ppm, 10 ppm, and 50 ppm concentration range in multiple cylinder sizes — providing prompt supply for scheduled calibration programmes and urgent replacement requirements, without the lead time uncertainty of sourcing reactive calibration gas from overseas suppliers.
Who It’s For
The Instrument Technician or Safety Officer at a Smelter or Refinery
You maintain SO2 gas detection across a non-ferrous metal smelter, petroleum refinery, or sulphur recovery unit where sulphur dioxide is generated in significant quantities as a process gas or combustion by-product. Your site operates a network of fixed SO2 detectors supplemented by portable instruments for maintenance and inspection work, and your maintenance programme requires regular span calibration of all SO2-configured detectors. You need certified 10 ppm or 50 ppm SO2 span gas in cylinder sizes that support your fixed calibration stations, with reliable local availability to maintain your calibration schedule without gaps — and with certified documentation that supports your site’s regulatory compliance records.
The HSE Manager at a Food Processing or Winemaking Facility
You’re responsible for worker safety at a food processing facility, winery, or beverage production plant where sulphur dioxide is used as a preservative or antimicrobial agent in food and wine production. Your SO2 detectors are calibrated to alarm at low-level TWA thresholds — the 5 ppm span gas option is the appropriate calibration reference for your detector configuration. You need calibration records that demonstrate your detector maintenance programme meets the occupational exposure monitoring requirements applicable to your facility, and you need a local supplier who can provide consistent supply of the correct concentration without the complexity of importing specialised calibration gas.
The Safety Equipment Procurement Officer for a Maritime or Multi-Industry Operation
You source calibration gas for a managed fleet of vessels carrying sulphur-containing cargo, a multi-site industrial operation spanning different SO2 risk levels, or a gas detector service company maintaining instruments for clients in smelting, refining, and chemical industries. You need consistent supply of certified SO2 span gas across one or more concentration variants, in cylinder sizes that balance per-calibration cost against changeout frequency. Alright Engineering Solutions can provide formal quotations for regular supply arrangements and assist with multi-concentration and multi-gas requirements across your portfolio.
Possible Applications
- Non-ferrous metal smelting — Span calibration of fixed and portable SO2 detectors at copper, zinc, nickel, and lead smelters where sulphur dioxide is generated during ore roasting and smelting operations, requiring continuous ambient monitoring and confined space entry detector calibration
- Petroleum refinery sulphur recovery units — Calibration of SO2 detectors in Claus sulphur recovery process areas, tail gas treatment units, and sulphur storage and loading facilities at oil refineries and gas processing plants
- Pulp and paper manufacturing — Detector calibration in kraft pulp mill recovery boiler areas, chemical preparation rooms, and bleach plant environments where SO2 is present as a process by-product or chemical agent
- Food and beverage processing — Calibration of low-range SO2 detectors used in wineries, dried fruit processing facilities, and food preservation operations where sulphur dioxide is used as a food additive and antimicrobial treatment
- Chemical manufacturing and sulphuric acid production — Span calibration of SO2 monitors in contact process sulphuric acid plants, sulphur dioxide liquefaction facilities, and chemical synthesis operations using SO2 as a process chemical
- Marine vessel cargo monitoring — Calibration of portable SO2 detectors used in hold entry procedures and cargo monitoring on vessels transporting sulphur, sulphur-containing ore concentrates, or sulphur dioxide in bulk or packaged form
- Power generation — flue gas desulphurisation — Detector calibration in FGD (flue gas desulphurisation) plant areas at coal-fired and heavy fuel oil power stations where SO2 monitoring is a continuous environmental compliance requirement
- Gas detector service and rental companies — Calibration gas supply for companies providing SO2-configured portable detector rental, calibration, and maintenance services to clients in smelting, refining, food, and chemical industries
Trust and Certifications
Certified Calibration Gas — Traceable Concentration Accuracy
Each cylinder is prepared to a certified SO2 concentration — 5, 10, or 50 ppm — with traceability documentation to national or international measurement standards appropriate for safety instrument calibration. For organisations whose gas detector maintenance programme is subject to ISO 9001 or ISO 45001 management system audits, or to regulatory inspection of instrument calibration records in smelting, refinery, or food safety regulatory contexts, certified span gas with traceable concentration documentation provides the evidence base that distinguishes a compliant calibration programme from one that cannot demonstrate reference standard accuracy.
Compliance Support for Occupational Exposure Limit Monitoring
Sulphur dioxide occupational exposure limits vary by jurisdiction but are consistently low — ACGIH TLV-TWA of 0.25 ppm, OSHA PEL of 5 ppm TWA, EU Indicative OEL of 0.5 ppm TWA — reflecting SO2’s acute respiratory toxicity even at low concentrations. Gas detectors monitoring compliance with these limits must be calibrated accurately at low-concentration ranges where sensor linearity and span accuracy are critical. The 5 ppm calibration gas option provides the low-range reference appropriate for OEL monitoring in general workplace applications, while the 10 ppm and 50 ppm options cover higher-range configurations in process-intensive industrial environments. This range covers the full span of SO2 monitoring requirements across regulated industries.
Suitable for Calibration of ATEX, IECEx, and SIL-Rated SO2 Detectors
Portable and fixed SO2 detectors deployed in classified hazardous areas carry ATEX or IECEx certifications confirming their design safety for use in potentially explosive atmospheres. Safety instrumented system (SIS) SO2 detectors may carry SIL ratings under IEC 61508 / IEC 61511 for use in process safety applications at refineries and chemical plants. Maintaining these instruments in calibration using certified traceable span gas is a condition of continued certified performance — and for SIL-rated instruments, calibration documentation using traceable reference gas is typically a specific requirement of the safety instrumented system validation and periodic proof-test plan. This SO2 span gas is suitable for calibration of ATEX-certified, IECEx-certified, and SIL-rated sulphur dioxide detection instruments.
Supplied by Alright Engineering Solutions — Singapore Gas Detection Specialist
The SO2 Sulphur Dioxide Balance Nitrogen Calibration Gas range is supplied by Alright Engineering Solutions Pte. Ltd., a Singapore-based distributor of portable and fixed gas detection equipment, calibration gases, and safety instrumentation. Alright Engineering Solutions supports smelting operations, petroleum refineries, food processors, maritime operators, and safety equipment service companies across Singapore and the Southeast Asian region with gas detection equipment supply, span gas sourcing, and technical support for gas detector maintenance programmes.
Accessories and Variants
SO2-Compatible Calibration Regulators
Sulphur dioxide is a reactive acidic gas that can attack certain regulator materials — particularly those with copper alloy components or elastomeric seals not rated for acid gas service. Using a regulator not compatible with SO2 service risks contamination of the calibration gas stream, loss of calibration concentration accuracy, and regulator damage over time. Alright Engineering Solutions supplies calibration regulators in materials appropriate for reactive acid gas service, with fixed-flow and demand-flow options to suit different detector calibration flow requirements. Regulator material compatibility confirmation before first use with SO2 span gas is strongly recommended.
Inert Calibration Tubing
Standard PVC calibration tubing can adsorb SO2 from the calibration gas stream — reducing the effective concentration delivered to the detector and introducing calibration error, particularly at the low 5 ppm concentration level where small absolute concentration losses represent a significant percentage of the certified value. PTFE or stainless steel tubing is recommended for SO2 calibration gas delivery to preserve certified concentration through to the detector calibration inlet. Alright Engineering Solutions can advise on appropriate tubing and calibration adapter options for your specific detector models.
Available Concentration Variants
This product is available in three certified SO2 concentrations:
5 ppm SO₂ Balance N2 — For low-range SO2 detector calibration in food processing, winemaking, laboratory, and general workplace OEL monitoring applications
10 ppm SO₂ Balance N2 — For mid-range STEL-referenced detector calibration and industrial hygiene monitoring in chemical and process industry environments
50 ppm SO₂ Balance N2 — For high-range process monitoring at smelters, sulphur recovery units, power generation facilities, and industrial SO2 handling operations
Related Span Gas Products from Alright Engineering Solutions
Hydrogen Sulphide (H₂S) Balance N2 — Toxic gas span gas for H₂S detector calibration in oil and gas, marine, and sewer and wastewater applications
Chlorine (Cl₂) Balance N2 — 5/10/50 ppm chlorine span gas for toxic gas detector calibration in water treatment, chemical, and food industry applications
Ammonia (NH₃) Balance N2 — 5/10/50 ppm ammonia span gas for refrigeration, chemical processing, and agricultural facility detector calibration
Multi-gas calibration mixtures — Combined toxic gas and LEL calibration mixtures for four-gas and multi-gas detector calibration programmes
Get in Touch
If you need to source SO2 Sulphur Dioxide Balance Nitrogen calibration gas — at 5 ppm, 10 ppm, or 50 ppm — for your sulphur dioxide detector maintenance programme at a smelter, refinery, food processing facility, maritime operation, or multi-site safety programme, contact Alright Engineering Solutions to confirm concentration and cylinder size availability and request a formal quotation.
Our team can also assist with SO2-compatible regulator and tubing selection, multi-gas calibration mixture sourcing, and sulphur dioxide gas detection equipment supply for your facility or fleet safety requirements.
📍 3791 Jalan Bukit Merah #06-01, E-Centre @ Redhill, Singapore 159471
