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GTT Cobra vs Herbert Arnold Zenit: Big-Boro Bench Torches

GTT Cobra vs Herbert Arnold Zenit for big boro: 130 jets on three stages against a single-grip German burner sized by head. Pressures, oxygen and price.

By Joe Blanchard, sixteen years on the distribution side of the glass industry · Updated

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Short answer: Both are bench burners for large borosilicate, built in opposite ways. The GTT Cobra stacks 130 jets in three separately valved fires, which GTT describes for furnace-size pieces, at $5,500. The Herbert Arnold Zenit is a single-stage concentric-ring burner with one twist grip, sold in 40, 50 and 65 mm heads; for big boro the head that competes with the Cobra is the 65 mm, which Arnold rates for tubing over 100 mm and lists at EUR 3,846 excluding VAT in the propane version. Choose the Cobra for staged control from a pinpoint to a very wide flame; choose the Zenit for one simple control on a burner sized to your tubing, at a lower price, if your work is boro or quartz.

If you are still mapping out a big-glass setup rather than choosing between these two, start with the guide to the best bench burner for thick glass sculpture, which frames the category before you narrow to a model.

The two designs at a glance

Both are bench-mounted surface-mix burners with a large oxygen appetite. The differences are in how the flame is built and controlled, what they run on, and what they cost. Figures come from each maker’s own pages and data sheets and are labelled as estimates where they are ours.

GTT CobraHerbert Arnold Zenit
Design3 stages, nine valves on six studsSingle concentric-ring head, one twist grip
Mix typeSurface mix (GTT calls it Triple Mix)Surface mix
MountBench, rack-and-pinion baseBench, cast-iron base with ball joint
Jets130 (7 Lynx center, 33 Mirage middle, 90 outer)Not published; 40, 50 or 65 mm head
GlassSoft and boro in our catalog; GTT’s page names noneBorosilicate; quartz on the hydrogen version
FuelPropane or natural gasSeparate propane, natural gas or hydrogen versions
Fuel / oxygen pressure20 psi / 80 psiPropane 50 mbar (about 0.7 psi) / 2.0 to 2.8 bar (about 29 to 41 psi)
Oxygen (estimate)~65 LPM at the largest usable flame~58 LPM maximum (40 mm propane); about 78 LPM maximum on the 65 mm
Price$5,500$3,300 US reference (40 mm); EUR 2,289 to 3,846 list

How each builds a big flame

The Cobra stacks three separately controlled fires: a 7-jet Lynx center, a 33-jet Mirage middle and a 90-jet outer fire, 130 jets in all. Each fire has its own fuel, oxygen and second-oxygen valve, which is how you can run the Lynx center alone for detail and bring in the middle and outer fires for fast melt-ins on production work. GTT markets the layout as part of its Triple Mix line; for how the fires layer, see GTT Triple Mix technology explained.

The Zenit reaches a large flame by head size instead of stages. Herbert Arnold builds it as three burners by fuel, 114/1 PSL (propane), 114/2 ESL (natural gas) and 114/3 WS (hydrogen), and rates each head in its catalog:

Zenit headBoro tubingMax flameQuartz tubing (hydrogen version)
40 mmabout 80 mmabout 40 mmabout 50 mm
50 mmup to 100 mmabout 50 mmabout 60 mm
65 mmover 100 mmabout 70 mmabout 80 mm

Ball valves and one twist grip carry the flame continuously from a needle point to a large, bushy flame, and the burner sits on a heavy cast-iron base with a ball joint so you can angle it to the work; it weighs 6.9 to 10.4 kg depending on head and fuel. The trade is fewer independent controls than the Cobra’s three fires, in exchange for a simpler burner chosen for a specific size of work. In Joe Blanchard’s sixteen years on the distribution side of the glass industry, the Zenits people bought and ran were the 40 mm and the 65 mm; for work in the Cobra’s class, that means the 65 mm. The ring design is covered in Herbert Arnold concentric ring burners.

Both are surface mix, which keeps the gases separate until at or just past the burner face. If that distinction is new to you, the surface mix vs premix torches guide explains why it matters for flame character and safety.

Noise

Neither maker publishes a decibel figure, so this is not a measured comparison. The Zenit’s reputation is a quiet, even flame, and earlier Arnold materials described it as noiseless and credited a flame-stabilizing system; that is the company’s framing and the burner’s reputation, not a number on its current data sheets. GTT does not market the Cobra on quietness; its emphasis is power and a wide flame. If all-day acoustic comfort is high on your list, weigh that difference in design intent, and if you can, stand next to both lit before you buy.

Gas supply and oxygen: plan it before the torch

Both are big burners, and the supply is the part to plan first. They also run at very different pressures.

GTT’s Flow Rate Chart puts the Cobra at 20 psi of fuel and 80 psi of oxygen at the largest usable flame on propane, the top tier of GTT’s line, with 138 CFH of oxygen, which is the ~65 LPM in our table. GTT notes that natural gas consumption runs about two and a half times the propane figures and that actual use is generally lower. The Cobra ships with 2 feet of 3/16 inch hose and screened adapters for 1/4 inch ID grade T hose, with 2 feet of 1/4 inch grade T hose on the outer studs.

The Zenit runs on low fuel pressure: 50 mbar on propane (about 0.7 psi), 22 mbar on natural gas (about 0.3 psi), and 500 mbar on hydrogen (about 7 psi), rising to 1,000 mbar (about 14.5 psi) on the 65 mm hydrogen head. Oxygen is 2.0, 2.5 and 2.8 bar by head on propane and 1.5, 2.0 and 2.8 bar on natural gas or hydrogen; Arnold’s Zenit brochure gives 3.5 bar (about 51 psi) for the 65 mm head where the catalog says 2.8, so ask which applies. Arnold publishes maximum consumption rather than a flow chart. For the 65 mm head that is 4.7 m3/h of oxygen on propane, 8.0 on natural gas and 8.8 on hydrogen, about 78, 133 and 147 LPM.

Those two kinds of figure are not comparable one to one: GTT’s is the flow at the largest usable flame, rounded, and Arnold’s is a ceiling. What they say together is that either torch at full size is a tank or bulk-oxygen burner, not a concentrator one. For how to feed a torch this size, see oxygen concentrators vs tanks for lampworking.

Compressed air works differently on each. The propane and natural-gas Zenits take compressed air as a standard third input at 0.5 to 1 bar (about 7 to 15 psi). GTT sells a separate compressed-air Cobra and specifies clean, dry air regulated to 60 psi or lower. Either way, the maker’s manual for your exact version sets the pressures and the flashback protection your torch and gas supply call for; Arnold recommends protection against reverse gas flow and flashback on its burners. Do not carry a pressure figure over from another model.

Editor’s note: the Cobra oxygen figure is GTT’s largest-usable-flame flow on propane, converted to LPM; the Zenit figures are Arnold’s maximum consumption, converted (m3/h x 16.67). Pressures in psi are our conversions from Arnold’s mbar and bar. Confirm current figures with each maker before you size a supply.

Price, configuration and what the money buys

The Cobra is $5,500 with the Mirage inner fire. The compressed-air Cobra is a separate product, and GTT’s own pages disagree on its price: $6,750 on the store and compressed-air index, $6,175 on the Cobra model page. The money buys three separately controlled fires, rack-and-pinion adjustment on a powder-coated base, and the widest flame envelope of the two. Foot-pedal and hose assemblies are sold separately.

The Zenit’s price moves with head and fuel. Arnold’s 02/2025 price list, excluding VAT:

Zenit headPropane (PSL)Natural gas (ESL)Hydrogen (WS)
40 mmEUR 2,794EUR 2,562EUR 2,289
50 mmEUR 2,999EUR 2,672EUR 2,511
65 mmEUR 3,846EUR 3,452EUR 3,386

Our $3,300 is a US reference figure for the 40 mm head, not Arnold’s price, so comparing it with the Cobra flatters the Zenit: the 65 mm head that matches the Cobra’s work costs more. The Zenit is still the less expensive burner on these figures, but the euro list excludes VAT and shipping, so get a landed US price from Arnold before you compare to the dollar. The list also carries cheaper N-M7 versions of the 40 and 50 mm heads; the catalog says the standard M7 head has no gas fine-adjustment screw and an optional head adds one, without saying which suffix is which, so ask. A US buyer should add Arnold’s US adapter set, which converts the gas, air and oxygen connections to 9/16 inch fittings.

Lead time, warranty and service

Neither maker publishes a lead time. GTT gives no dated delivery commitment and warns that material availability can delay torches; Arnold’s documents name none, and a Zenit ships from Germany. If your timeline is tight, ask both for a current date before you commit.

On after-sale terms, GTT gives a one-year warranty against factory defects, and Arnold’s terms limit defect claims to 12 months from delivery. Arnold also offers an on-site service visit for the Zenit, in which jets are checked, the air taps greased and the burner adjusted, at a fixed inspection price it does not publish.

Which to choose

Pick the Cobra if you want the flexibility of three separately controlled fires on one torch, moving between a fine Lynx pinpoint and a very wide melt-in flame, and if furnace-size pieces are the daily job. You pay more, and you feed a large oxygen supply at high pressure.

Pick the Zenit if your work is boro or quartz, you prefer one simple control to three sets of valves, and you can size the head to your largest tubing, which for work in the Cobra’s class means the 65 mm. It costs less on our figures and runs on low fuel pressure, in exchange for fewer independent flame controls and euro pricing from Germany.

What should not decide it is buying the bigger or more expensive torch as a statement. Size the torch to the largest piece you make regularly, then size your oxygen supply to the torch. A large burner starved for oxygen performs worse than a right-sized one fed correctly. If the Cobra is more torch than your work needs, Herbert Arnold Zenit vs GTT Mirage sets the Zenit against GTT’s two-stage Mirage; if it is not enough, GTT Cobra vs Viper covers GTT’s 200-jet Viper.

Sources

About the author

Written and edited by Joe Blanchard, who spent 2007 to 2023 on the distribution side of the glass industry in Asheville, North Carolina. GlassTorches.com is his independent, manufacturer-first buyer's guide. More about the editor.

How this guide was sourced: figures come from the manufacturer's own pages and manuals where we have them and are labelled as estimates where they are ours; the catalog on this site is the source of truth, and where sources disagree the guide says so. Confirm the current spec with the maker before you buy. How we work.