What Is a Sonic Flare and How Does It Work?
A sonic flare is a smokeless flare that uses the flare gas pressure itself, not a blower or steam, to burn waste gas cleanly. The pressure accelerates the gas to near-sonic velocity at the tip, creating strong turbulence that pulls in surrounding air for complete combustion. That high-velocity mixing eliminates smoke, lowers flame radiation, and shortens the flame.
Because the energy comes from pressure you already have, a sonic flare removes the need for air-assist blowers and reduces stack complexity. Fixed orifice sonic flares typically run on 15 to 100 psig. Tell us your header pressure and we will confirm the fit.
Variable Slot vs Fixed Orifice: Which Sonic Flare to Choose
Both sonic tips burn smokeless without a blower, so the choice comes down to how much your flow varies. If your flow swings widely, the variable slot orifice (Coanda) tip gives the widest smokeless turndown by opening and closing with flow, needing about 30 psig minimum.
If your flow is steadier and you have higher, more consistent pressure, the simpler fixed orifice tip is a cost-effective fit for continuous or emergency duty in the 15 to 100 psig range. Send us your min, normal, and peak flows with available pressure and we will recommend the right tip.
Sonic Flare vs Air-Assist Flare: When to Choose Sonic
Air-assist flares add a blower to supply mixing air, which suits sites with low gas pressure. A sonic flare skips the blower and uses your gas pressure for mixing, so it is the more economical, lower-maintenance choice whenever you have enough pressure — generally about 30 psig or more.
That means lower capital cost, less stack complexity, and no blower power or upkeep. If you are short on pressure, air assist is the better fit; if you have pressure to spare, sonic usually wins on cost and simplicity.
Have Flare Gas Pressure to Spare?
Tell us your header pressure and flow range and our engineers will confirm whether a variable slot or fixed orifice sonic flare keeps you smokeless without a blower.
Pressure, Turndown, and Smokeless Performance
Fixed orifice sonic tips run on roughly 15 to 100 psig depending on gas composition, while the variable slot orifice tip needs about 30 psig minimum. The payoff of the variable design is turndown: because the orifice opens and closes with flow, it holds high exit velocity and 100% smokeless performance from purge rate up to maximum flow.
Sonic tips also keep purge requirements and stack complexity low. Share your pressure and turndown range and we will size the tip to stay smokeless across all of it.
What Makes a High-Quality Sonic Flare System
Sonic flares accelerate waste gas to sonic velocity at the tip exit, using the momentum of the high-velocity gas stream to entrain ambient air for combustion without a blower or external assist media. Achieving reliable smokeless operation at sonic conditions requires precision in five design areas.
Tip orifice area precisely matched to the operating pressure and flow range. Sonic conditions require a minimum upstream pressure (typically 15 to 60 psig). A tip undersized will not reach sonic velocity at low flows; a tip oversized will produce sub-sonic exit velocity and fail to entrain sufficient combustion air.
Tip metallurgy rated for the thermal shock of intermittent operation. Sonic tips experience rapid thermal cycling during well test and blowdown events, cold tip to full combustion temperature in seconds. Austenitic stainless steel (316L minimum) or Alloy 625 materials tolerate this cycling; standard 304 SS or carbon steel develops fatigue cracking after repeated thermal shock events.
Stable combustion during pressure transients. Production site pressures fluctuate during separator upsets, pig launches, and liquid slug events. Sonic tip designs with a wide stable combustion envelope, typically achieved through multi-orifice tip geometry rather than a single central orifice, maintain stable combustion during pressure transients that would extinguish a single-orifice design.
Stack height and radiation setback appropriate for the flow rate. Sonic flares operating at high flow rates produce significant visible flame length and thermal radiation. Confirm stack height and radiation setback calculations are based on the maximum credible flow rate, not the average operating rate, to ensure personnel and equipment safety during peak events.
Pilot shroud designed for high-wind environments. Sonic tip exit velocity creates a local high-velocity gas zone that can extinguish a conventional pilot flame. High-quality sonic flare designs include a pilot shroud or windshield positioned to shield the pilot flame from the waste gas jet and ambient crosswind, maintaining reliable ignition across the expected wind speed range.
Why Engineers Choose Hero Process Solutions
| What You Need | How Hero Process Solutions Delivers It |
|---|---|
| 98% DRE documentation for permit compliance | In-house combustion engineers provide site-specific performance certifications backed by tip-specific test data |
| Equipment on-site before the compliance deadline | Rental fleet deployable in 24 to 72 hours across the Permian Basin, Mid-Continent, Appalachia, and Rockies |
| Manufacturer that designs its own tips | All combustion tips designed, fabricated, and tested at Hero Process Solutions’ Kellyville, Oklahoma facility |
| Field service when equipment needs attention | Direct HPS field technicians, not third-party contractors, cover major producing regions |
| Equipment for multiple applications | Air-assist, sonic, gas-assist, low-flow, emergency, and portable flares plus vapor combustors and VRUs from one manufacturer |
Hero Process Solutions is a US-based manufacturer and rental provider serving upstream, midstream, pipeline, and industrial clients since the company’s founding under the Hero Flare brand. Contact (918) 941-2166 or email sales@hero-ps.com to discuss your application. Engineering specifications and rental availability are provided within one business day of inquiry.
Compliance and Destruction Efficiency
Both the variable slot orifice and fixed orifice tips are fully EPA compliant and provide proven performance to achieve 98% destruction efficiency, the level operators design to under 40 CFR 60.18. Because the gas pressure provides the mixing energy, sonic flares deliver this compliant performance without a blower.
We can provide compliance language and performance data for your permitting package. See our OOOOb/c overview. Need a unit fast? Check flare rentals.
Applications and Industries Served
Sonic flares fit any site with enough flare gas pressure to drive smokeless combustion without a blower. Common uses include high-pressure relief, continuous and emergency flaring, and gas handling across production, gas processing, and midstream facilities.
Operators in the Permian Basin, Oklahoma, Marcellus, and Haynesville plays use sonic tips to stay smokeless and compliant while avoiding blower cost. View all markets served.
Sonic Flare FAQs
A sonic flare achieves smokeless combustion by accelerating the waste gas through a specially engineered tip at sonic or near-sonic velocity. The high-momentum jet entrains ambient air at the combustion zone, providing the turbulent mixing needed for complete, smoke-free combustion without external assist media such as steam or air blowers.
Sonic flares require sufficient upstream pressure to accelerate gas to sonic velocity at the tip. Typically a minimum of 15-30 PSIG is required at the flare inlet, though exact requirements depend on gas molecular weight and design flow rates. Hero Process Solutions engineers the tip geometry to your available pressure range.
The sonic velocity jet creates a high-shear interface between the waste gas and surrounding air. This turbulence promotes rapid mixing and complete combustion before soot particles can form. The momentum-driven air entrainment effectively replaces externally supplied assist media, making sonic flares self-sufficient for smokeless operation.
Yes. Sonic flares are well-suited for high-pressure emergency relief applications because they are designed for high-velocity, high-pressure flow conditions. They maintain smokeless performance across a wide turndown range, including large transient relief flows from PSV or PVRV discharges.
Properly designed sonic flares routinely achieve DRE values of 98% or greater, with many installations achieving 99.9%+ for hydrocarbons. Hero Process Solutions provides combustion efficiency documentation and can support permit applications requiring specified DRE values.
Yes. Sonic flares are tolerant of composition variability because the combustion mechanism relies on physical momentum rather than fixed chemical stoichiometry. However, significant changes in molecular weight affect sonic velocity and tip performance, so Hero Process Solutions designs tips with a defined composition envelope and consults on operation outside that range.
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Related Flare Systems & Resources
Explore other Hero flare configurations or browse the full product line to find the right match for your application.
Air Assist Flares
Motor-driven blower assist for smokeless combustion without steam or high-pressure gas.
Gas-Assist Flares
Smokeless burning where high-pressure assist gas is available on-site.
Utility & Emergency Flares
Reliable destruction for relief and upset events. Designed for peak emergency flow rates.
Portable Flares
Trailer-mounted units for temporary operations, well completions, and rental jobs.
Low-Flow Flares
Clean combustion for small and intermittent vent streams with minimal assist requirements.
Datasheets Library
Download model spec sheets and capacity tables for all Hero flare configurations.