Gas Data GM25-4

The Gas Data GM25-4 brings together simultaneous measurement of key landfill and contamination gases with pressure and flow in one compact, hand-held analyser. Its fixed six-channel configuration covers methane, carbon dioxide, oxygen, hydrogen sulphide, carbon monoxide and hexane, enabling comprehensive gas profiling without swapping sensors or reconfiguring the instrument on site. This fixed approach simplifies operation, reduces set-up time and supports consistent measurement protocols across large monitoring programmes.

Beyond gas concentration, the instrument measures atmospheric, static and differential pressures, as well as bidirectional borehole flow. This combination gives clear insight into subsurface behaviour, system performance and gas migration pathways, supporting more robust engineering assessments and regulatory submissions.

The GM25-4 is purpose-designed for site investigation, landfill gas control and environmental compliance monitoring across greenfield, brownfield and landfill-affected sites. Typical applications include borehole monitoring, landfill perimeter checks, in-waste gas wells and contaminated land assessments where multiple contaminants and parameters must be monitored together.

High accuracy and defined ranges for each gas channel support professional assessment work, while an LEL indication calculated from gas readings helps raise flammability risk awareness on site. The dedicated hexane channel and a PID correction factor for indicative VOC measurement make the analyser particularly valuable where hydrocarbon vapours contribute to overall site risk.

For monitoring in potentially explosive atmospheres, the Gas Data GM25-4 carries ATEX, IECEx and UKEx certification for use in Zone 1 hazardous areas when configured correctly and deployed under suitable risk assessments. Its EEx ib IIB T1 intrinsic safety rating reflects a design focused on safe operation in environments affected by landfill gas and other flammable atmospheres. This allows asset owners, contractors and regulators to obtain detailed gas, pressure and flow data without compromising site safety requirements.

The analyser is compact, lightweight and hand-held, making it straightforward to carry between boreholes, gas wells and monitoring locations. A rugged, weather-proof neoprene case protects the instrument from typical landfill and outdoor conditions, while a high-contrast LCD display maintains readability in varied lighting. The wide ambient operating temperature range and defined minimum aspiration performance support reliable sensor response under typical field conditions.

A user-swappable battery pack provides a typical 8–12 hours of operation with around a 4-hour recharge, enabling full working-day deployments. A charger tailored to the destination country supports international roll-out, and the fully portable, battery-powered design reduces reliance on external power at remote or difficult-access sites.

Where detailed flow and pressure information is critical, the GM25-4 is configured specifically for higher flow-rate measurement applications than the GM25-3. It uses an internal flow transducer, rather than calculated flow, with tightly specified differential pressure and flow measurement performance to support reliable engineering evaluations of extraction systems and gas collection infrastructure. Bidirectional flow measurement enables assessment of both extraction and ingress within boreholes or pipework, clarifying gas movement and system effectiveness.

For extended capability, optional accessories include a vane anemometer for gas velocity measurements over a wide range, suited to vent or duct surveys, and a brass temperature probe for gas temperature measurement where thermal data forms part of the investigation.

Data logging and hierarchical data storage are built in, allowing detailed datasets to be captured across multiple locations and campaigns. Using free Instrument Connect software, users can transfer data to a PC via USB and export results in CSV format for analysis, reporting and integration with wider environmental management systems. The software also supports management and upload of sample point labels so data from repeated visits remains structured, traceable and audit-ready.

The analyser integrates with the DataField GM25 Connect app, enabling remote control from a mobile device or tablet. Measurement routines can be configured to suit specific projects, and, with an internet connection, readings can be live-streamed to a web-based portal for real-time visibility. These remote data management capabilities help teams shorten time on site, accelerate decision-making and reduce manual download and transcription effort.

Despite its breadth of capability, the Gas Data GM25-4 is intentionally straightforward to operate, with clear status indication and calibration validity shown on the home screen before deployment. Comprehensive documentation, including a detailed datasheet, user manual and GM25 range comparison chart, supports correct product selection, configuration and use.

An annual service and calibration interval is recommended to maintain accuracy and compliance. Typical service packages include calibration, part replacement and options for rental cover to minimise downtime, with collection and return shipping often available depending on supplier. Calibration due dates are clearly indicated on both the instrument and calibration certificate, helping organisations demonstrate traceability for environmental audits and regulatory checks.

The GM25-4 is available for purchase or for short- and long-term hire, aligning with both long-term monitoring strategies and project-based work. Lead times typically reflect build-to-order manufacture and quality control processes. Ongoing support is underpinned by an established distributor and service network, including access to spares and consumables, free technical support, product training and demonstrations. Together, these elements provide a robust platform for repeatable, defensible gas, pressure and flow measurements across complex environmental assessments.