Landfill sites around the world face a persistent engineering challenge: how to safely and efficiently destroy the methane and trace contaminants generated by decomposing waste, while meeting increasingly strict emissions standards. The Organics US SC (Standard Combustor) Class of flare stacks was purpose-built to address this challenge for the United States market and other regions where US regulatory preferences apply.
This data sheet-based overview explains what the US SC Class flare is, the problem it solves, how it works, and the key specifications engineers and site operators need to know.
What Is the US SC Class Flare Stack?
The US SC Class is a landfill gas flare stack designed and manufactured specifically for use in the USA and in locations worldwide where US emissions and design preferences are followed. Unlike some international flare designs, the US approach favors a longer gas retention time combined with somewhat lower flame temperatures.
Organics’ US SC Class flare maintains higher combustion temperatures while extending retention time from a baseline of 0.3 seconds up to a minimum of 0.6 seconds, at a temperature of at least 1,000°C. This combination is central to achieving reliable destruction of trace contaminants found in landfill gas.
Key design principle: Retention time is doubled compared to the standard baseline — from 0.3 seconds to a minimum of 0.6 seconds — while temperature is held at a minimum of 1,000°C.
The Problem: Balancing Time, Temperature, and Emissions
Successfully destroying landfill gas contaminants isn’t simply a matter of burning hotter. The Destruction Efficiency Rating (DER) of any combustion process is a trade-off between time and temperature:
- Higher temperatures allow for shorter residence times.
- Municipal incinerators, for comparison, typically require temperatures above 850°C sustained for 2 seconds.
- Landfill gas flares can achieve higher combustion temperatures, allowing shorter residence times than incineration.
- However, there’s a ceiling: at approximately 1,200°C, thermal NOx formation begins to increase sharply, which can undermine the environmental benefit of higher-temperature combustion.
Controlling combustion air is critical to making this balance work in practice. The system must maintain homogenous conditions within the flare shroud without excessively diluting the combustion gases — a precise engineering challenge that the US SC Class is designed to solve.
How It Works
The US SC Class flare uses a non-visible, partially pre-aerated, turbulent diffusion flame for combustion, paired with automatic flame temperature control. This ensures the flame remains stable and within specification even as gas flow and composition vary.
Key operational features include:
- Automatic flame temperature control to maintain the 1,000°C minimum design temperature
- Booster turn-down to zero flow without surging, allowing the system to respond smoothly to fluctuating gas supply
- High-reliability landfill gas pilot for consistent ignition
- Self-checking UV flame detection sensors for safety monitoring
- Flame arrestors fitted on both the gas booster inlet and outlet
Control Panel and Automation
The SC Class flare units include a flexible, PLC-based (Programmable Logic Controller) control panel. This allows for:
- Dual-stage trigger levels for alarms or shutdowns, based on methane and oxygen analyser inputs
- Fully adaptable delay times and re-ignition sequences to suit local operating requirements
- A 20% expansion factor built into the panel, allowing future retrofitting of additional control equipment — such as a telemetry unit — without redesigning the panel or rewiring the system
This means that as regulatory or site requirements evolve, the control system can be extended rather than replaced.
Technical Specifications
| Parameter | Specification |
|---|---|
| Flow rate range | 100 to 15,000 cubic metres per hour |
| Pressure rise across gas booster | 150 mbar |
| Flame temperature | 1,000°C minimum |
| Retention time | 0.6 seconds minimum |
| Minimum methane concentration for combustion | 25% |
| Number of inlets | 2 flanged inlets (standard); additional inlets available on request |
| Flow control | Chemical duty butterfly valves |
| Pipework finish | Hot dip galvanised to industry standard |
| Burner material | High temperature stainless steel |
| Flame arrestor | Fitted on gas booster inlet and outlet |
| Flame detection | Self-checking UV sensor |
| Colour | Battleship Grey or customer specification |
Construction note: Fully stainless steel combustion chambers are available as an option, offering an increased life-cycle and enhanced visual appearance over standard galvanised or high-temperature painted finishes.
Construction and Site Practicalities
All pipework on the US SC Class flare is fully galvanised, and the ground flare shroud is either galvanised or finished with high-temperature paint, depending on flow rate and shroud size. For sites wanting greater durability or a more polished appearance, a fully stainless steel construction option is available.
The units are also skid-mounted for ease of movement around site — a practical benefit for landfill operations where equipment may need to be relocated as the site develops. A range of optional instrumentation, including flow rate and gas concentration measurement, along with remote access and datalogging options, allows the flare to be integrated into broader site monitoring systems.
Where the SC Class Fits: Choosing the Right Flare
The SC Class flare stack is designed to meet the minimum specification required to satisfy DRE requirements — maintaining a minimum flame temperature of 1,000°C for a minimum retention time of 0.3 seconds in its baseline form, extended to 0.6 seconds in the US SC configuration described here.
For applications requiring higher-temperature combustion, Organics offers the MC (higher-temperature) Class of flare units as a step up from the SC Class, covered in a separate data sheet (ODSF03).
This tiered approach allows landfill operators and environmental engineers to select the flare configuration that matches their specific emissions standards and site conditions, rather than over-specifying equipment.
Key Takeaways
- The US SC Class flare stack is engineered for US markets and jurisdictions following US emissions preferences, using a longer retention time (0.6 seconds minimum) at 1,000°C minimum to destroy landfill gas contaminants.
- The design carefully balances time and temperature, avoiding the sharp rise in thermal NOx formation that occurs above roughly 1,200°C.
- Standard units handle flow rates from 100 to 15,000 cubic metres per hour, with a PLC-based control system that supports methane/oxygen gas analysis, automated alarms, and future expansion.
- Construction options range from galvanised steel to fully stainless steel, with skid-mounting for site flexibility.
- For higher-temperature requirements, the MC Class flare provides a step up from the SC Class baseline.
Get in Touch
If you’re evaluating flare stack options for a landfill gas management project and want to understand whether the US SC Class is the right fit for your site’s emissions and flow requirements, our team is ready to help. Contact us to discuss your specifications and get tailored guidance on flare selection, control systems, and installation.