Cart (
Overview
Gas detectors are only as reliable as the calibration behind them. In confined space entry, offshore operations, and industrial gas monitoring, an uncalibrated or poorly calibrated detector is not just a compliance failure — it is a direct safety risk to the workers depending on it. Span gas is the calibration standard that determines whether your detector responds correctly to the gases it is designed to detect, at the concentrations that matter. Without regular bump testing and calibration using the correct span gas mixture, there is no way to confirm that a gas detector will alarm at the right concentration when it counts.
This four-gas span gas cylinder — Pentane 25% LEL, H2S 25ppm, CO 100ppm, O2 19%, Balance Nitrogen — is a certified calibration gas mixture formulated to simultaneously verify the response of combustible gas (LEL), hydrogen sulphide, carbon monoxide, and oxygen sensors in a single pass. Available in cylinder sizes from 34 litres to 116 litres, it is compatible with the full range of portable and fixed multi-gas detectors used across the oil and gas, marine, petrochemical, and industrial sectors.
What makes this particular mixture the correct calibration reference for the majority of multi-gas detector users is the combination of gas selection and concentration. Pentane at 25% LEL, H2S at 25ppm, CO at 100ppm, and O2 at 19% vol are the standard calibration concentrations specified by the majority of leading portable multi-gas detector manufacturers — including MSA, Honeywell BW, Industrial Scientific, Draeger, and Riken Keiki — for their four-gas instruments. Using a certified span gas cylinder at these concentrations ensures that calibration results meet the manufacturer’s verification standard and provide defensible documentation of detector performance for safety management records.
Key Features
Four-Gas Mixture in a Single Cylinder
This cylinder contains all four gases required for full multi-gas detector calibration — combustible gas (Pentane at 25% LEL), hydrogen sulphide (H2S at 25ppm), carbon monoxide (CO at 100ppm), and oxygen (O2 at 19%) — balanced in nitrogen. For safety teams managing portable multi-gas detectors across a workforce, a four-gas span gas cylinder eliminates the need to stock and manage separate single-gas cylinders for each sensor type. One cylinder, one bump test or calibration routine, full four-sensor verification — reducing calibration complexity, storage requirements, and the risk of an incomplete calibration due to a missing single-gas cylinder.
Pentane as the Combustible Gas Reference
Pentane is the preferred combustible gas reference for many multi-gas instrument manufacturers because of its stability in calibration gas mixtures and its consistent, predictable response across catalytic bead and infrared LEL sensors. At 25% LEL, this mixture provides a mid-range calibration point that verifies the detector’s response across the operational detection range without over-ranging the sensor. For operations in environments where hydrocarbon gases are present — refineries, petrochemical plants, offshore platforms, fuel handling areas — Pentane-calibrated LEL sensors provide a reliable combustible gas detection baseline.
H2S at 25ppm — Relevant Calibration Concentration for Confined Space and Industrial Work
Hydrogen sulphide is one of the most acutely hazardous gases encountered in confined space entry, sewage system work, oil and gas production, and marine cargo operations. The OSHA ceiling limit for H2S is 20ppm, with immediately dangerous to life and health (IDLH) concentrations starting at 100ppm. Calibrating the H2S sensor at 25ppm places the calibration point above the regulatory ceiling limit, confirming that the sensor can detect and alarm at concentrations in the critical range where worker exposure risk is highest. For safety managers operating in H2S-risk environments, 25ppm calibration is the standard that aligns with both regulatory limits and manufacturer calibration specifications.
CO at 100ppm — Verified Against the IDLH Threshold
Carbon monoxide at 100ppm represents a calibration concentration close to NIOSH’s immediately dangerous to life and health threshold of 1,200ppm (with regulatory action levels and TWA limits far below), providing a meaningful calibration reference that confirms sensor sensitivity and response in the range where CO exposure becomes acutely dangerous. For industries where CO risk is present — enclosed engine rooms, boiler rooms, vehicle maintenance workshops, tunnel construction, and confined space work near combustion equipment — accurate CO sensor calibration is a fundamental requirement of a reliable gas detection programme.
O2 at 19% — Oxygen Deficiency Reference
The oxygen sensor in a multi-gas detector is calibrated to identify both oxygen deficiency (below 19.5% vol, the OSHA threshold for oxygen-deficient atmospheres) and oxygen enrichment (above 23.5% vol, which increases fire and explosion risk). By including O2 at 19% — just below the oxygen deficiency alarm threshold — this mixture verifies that the oxygen sensor responds correctly to depleted oxygen atmospheres, which are the primary oxygen hazard in confined space entry. Workers entering confined spaces such as tanks, voids, manholes, and enclosed machinery spaces depend on accurate oxygen sensor calibration to receive reliable low-oxygen alarms.
Balance Nitrogen — Inert, Stable Carrier Gas
Nitrogen is used as the balance gas in this mixture because it is inert, non-reactive, and does not interfere with the calibration response of any of the four active gas components. Nitrogen balance gas also ensures the mixture is non-flammable at the cylinder concentrations supplied, making it safe to store and transport in accordance with standard compressed gas cylinder handling procedures. The inert balance gas also contributes to mixture stability over the cylinder’s shelf life, maintaining accurate concentration values from the first use to the last.
Multiple Cylinder Sizes — 34L to 116L
The cylinder is available in five sizes: 34L, 58L, 103L, 110L, and 116 litres. Smaller 34L cylinders suit teams with a small number of detectors and limited storage space, or operations requiring a portable calibration gas supply in the field. Larger 103L–116L cylinders reduce the cost per calibration event and extend the time between cylinder replacements for teams running large detector fleets with frequent bump testing requirements. Having the right cylinder size for the operation reduces both per-calibration cost and the administrative burden of frequent cylinder replacements.
Technical Specifications
Product Type: Four-Gas Certified Calibration Span Gas Mixture
Cylinder Sizes (C10): 34L / 58L / 103L / 110L / 116 Litres
Carbon Monoxide (CO): 100 ppm
Hydrogen Sulphide (H2S): 25 ppm
Pentane (Combustible Gas): 25% LEL
Oxygen (O2): 19% Vol
Balance Gas: Nitrogen (N2)
Benefits
One cylinder covers all four standard multi-gas detector sensors. Rather than managing four separate single-gas cylinders for bump testing and calibration, this mixture handles the full sensor set in a single connection. For safety teams responsible for detector maintenance across multiple workers or shifts, this reduces calibration time, simplifies stock management, and eliminates the risk of an incomplete calibration because a single-gas cylinder ran out or was not available.
Calibration concentrations aligned with major detector manufacturer specifications. The four-gas concentrations in this mixture — Pentane 25% LEL, H2S 25ppm, CO 100ppm, O2 19% — match the calibration gas specifications published by the majority of leading portable multi-gas detector manufacturers. Using the manufacturer-specified span gas concentration ensures calibration results meet the instrument’s design verification standard, which matters for both detector reliability and warranty compliance.
Supports regulatory compliance and safety management documentation. Regular bump testing and calibration with certified span gas is a documented requirement under OSHA confined space entry standards, IMO/MLC requirements for marine operations, and the safety management systems of most major oil and gas operators. Maintaining calibration records with the correct span gas reference — concentration, cylinder lot number, and calibration date — provides the documentary evidence required for audit, inspection, and incident investigation purposes.
Extends detector service confidence between maintenance intervals. A detector that has been bump tested against a certified four-gas span gas cylinder immediately before use gives the worker and the safety manager confidence that all four sensors are responding correctly at that moment. For confined space entry — where a delayed or absent alarm can be fatal — that confirmation is not a procedural formality. It is the verification step that determines whether the detector can be trusted in the field.
Flexible cylinder sizing reduces cost per calibration. Choosing the right cylinder size for the team’s detector count and bump testing frequency optimises the cost per calibration event. Larger cylinders reduce the effective cost per litre of calibration gas and extend the time between procurement cycles, which matters for operations running high-frequency daily bump testing programmes across large detector fleets.
Who It’s For
The HSE Officer Managing Confined Space Entry Programmes
You’re responsible for the gas testing programme before every confined space entry on your site. Your team uses portable four-gas monitors and your site procedure requires a bump test before each entry. You need a reliable supply of the correct four-gas span gas mixture — at the right concentrations for your detectors — to ensure that every bump test is conducted with a certified calibration reference. You also need the calibration documentation to be audit-ready for your safety management system records and any regulatory inspection. This cylinder gives you the gas, the concentrations, and — when purchased with a certificate of analysis — the documentation.
The Offshore Safety Coordinator or Platform Toolpusher
Your operation runs multiple four-gas detectors across a workforce doing hot work permits, confined space entries, and routine atmospheric monitoring in areas with H2S and combustible gas risk. Calibration gas supply needs to be reliable, correctly specified for your detectors, and available in cylinder sizes that suit your platform storage capacity and the volume of daily calibrations you run. The 103L and 116L cylinders are practical for high-frequency offshore calibration programmes, and the four-gas mixture covers the full sensor set your instruments require in a single cylinder.
The Marine Safety Officer or Chief Officer on a Tank Vessel
Confined space entry into cargo tanks, void spaces, and enclosed machinery spaces is a routine part of marine operations, and every entry requires atmospheric testing with a calibrated gas detector. H2S, CO, LEL, and O2 are the four gases your instruments need to monitor, and the same four gases this span gas cylinder is formulated to verify. Regular bump testing before every tank entry, calibration at the frequency required by your SMS and the detector manufacturer, and correct span gas documentation for your vessel’s maintenance records are all supported by this cylinder.
Possible Applications
- Confined space entry atmospheric testing — Bump testing and calibration of four-gas monitors before entry into tanks, vessels, manholes, sewers, voids, and enclosed spaces across any industry where confined space entry is conducted
- Oil and gas upstream and downstream operations — Calibration of LEL, H2S, CO, and O2 sensors on portable gas monitors used in drilling, production, refining, and gas processing environments
- Offshore platform and FPSO gas detection programmes — Daily bump testing and periodic calibration of portable four-gas monitors used by offshore workers across exploration, production, and accommodation areas
- Marine cargo tank and enclosed space entry — Calibration of portable gas detectors used for atmospheric testing before entry into cargo tanks, engine rooms, pump rooms, and void spaces on tankers, bulk carriers, and offshore vessels
- Petrochemical plant and refinery safety programmes — Routine calibration maintenance for gas detection instruments used in process areas with hydrocarbon, CO, and H2S exposure risk
- Utilities and wastewater treatment facilities — Bump testing of multi-gas monitors used by utility workers entering sewage systems, pump stations, and treatment plant confined spaces where H2S and CO are present
- Tunnelling and underground construction — Calibration of gas monitors used by workers in enclosed tunnel environments where exhaust CO, ground gases, and oxygen displacement are hazards
- Fire service and emergency response teams — Calibration gas supply for HAZMAT and gas detection equipment operated by industrial fire brigades and emergency response teams in high-hazard facilities
Trust and Certifications
Certified Calibration Gas Mixture
Span gas cylinders used for detector calibration should be supplied with a certificate of analysis (CoA) confirming the actual concentration of each gas component, the mixture preparation date, the cylinder lot number, and the stated shelf life. A certified calibration gas mixture provides the traceability required to confirm that the gas used in calibration meets the concentration specification — which is the foundation of a defensible calibration record. Uncertified or unverified calibration gas introduces uncertainty into the calibration result, which undermines the purpose of the calibration exercise.
Compliance with Detector Manufacturer Calibration Requirements
The concentrations in this mixture — Pentane 25% LEL, H2S 25ppm, CO 100ppm, O2 19% — are aligned with the calibration gas specifications published by major portable multi-gas detector manufacturers including MSA, Honeywell BW, Industrial Scientific, Draeger, and Riken Keiki for their standard four-gas instruments. Using manufacturer-specified calibration gas concentrations ensures calibration results are valid under the manufacturer’s instrument specification and supports warranty compliance where calibration records are required.
Supplied by Alright Engineering Solutions
This span gas cylinder is supplied by Alright Engineering Solutions Pte. Ltd., a Singapore-based distributor of portable and fixed gas detection equipment, calibration gas, and industrial safety instruments. Alright Engineering Solutions serves the marine, oil and gas, petrochemical, and industrial safety sectors across Singapore and the regional market, providing span gas supply, gas detector sales, calibration accessories, and technical support for gas detection programmes.
Accessories and Variants
Demand-Flow Regulator
A demand-flow regulator is required to connect the span gas cylinder to a portable gas detector for bump testing and calibration. Demand-flow regulators deliver gas only when the detector’s pump is actively drawing — preventing gas waste and ensuring the correct flow rate for accurate sensor response during calibration. Alright Engineering Solutions can advise on the correct regulator specification for your cylinder valve type and detector model.
Fixed-Flow Regulator
Fixed-flow regulators deliver calibration gas at a constant specified flow rate and are used with detectors that require a fixed flow input for calibration. Available in a range of flow rates to match different detector calibration inlet specifications. Contact our team to confirm the correct flow rate for your instrument model.
Calibration Gas Tubing and Adapters
Silicone or PTFE calibration tubing and instrument-specific calibration cup adapters are available to connect the regulator output to the detector’s sensor inlet or calibration port. Using the correct tubing and adapter ensures a leak-free connection and prevents dilution of the calibration gas before it reaches the sensor.
Available Cylinder Size Variants
34 Litre (C10) — Compact cylinder for small teams, field use, or low-frequency calibration requirements
58 Litre (C10) — Mid-range cylinder balancing portability and calibration capacity
103 Litre (C10) — Higher capacity for medium-sized detector fleets and regular bump testing programmes
110 Litre (C10) — Extended capacity cylinder for high-frequency calibration operations
116 Litre (C10) — Largest available size for high-volume calibration programmes and fleet-scale daily bump testing
Get in Touch
If you need to source the Pentane 25% LEL / H2S 25ppm / CO 100ppm / O2 19% Balance N2 span gas cylinder for your gas detection calibration programme — whether for a single worksite, a vessel, or a multi-site safety programme — contact Alright Engineering Solutions to confirm cylinder size availability and request a formal quote.
Our team can also advise on compatible regulators, calibration accessories, and portable gas detection instruments to support your complete calibration programme.
📍 3791 Jalan Bukit Merah #06-01, E-Centre @ Redhill, Singapore 159471
