Short answer: The GTT Bobcat does not need a big oxygen supply. Glass Torch Technologies says it runs well on a 5 LPM, 5 psi oxygen concentrator, is optimal on 8 LPM, and does extremely well on 10 LPM or tanked oxygen. The ~8.5 LPM figure in our catalog is the oxygen GTT’s flow rate chart gives for the Bobcat’s largest usable flame on propane, so it is a ceiling, not a minimum. If you own one 5 LPM concentrator, the Bobcat will work on it; if you want the whole flame range on tap, plan for 8 to 10 LPM or tanks.
The rest of this page explains where each number comes from and what GTT says about flashback protection on a concentrator. For the general theory of torch oxygen demand, see how many LPM does my torch need.
What GTT says about the Bobcat’s oxygen
The Bobcat is GTT’s standard surface-mix bench torch: 7 jets, a single stage, and propane or natural gas as the fuel. It is not a Triple Mix torch. GTT’s patented Triple Mix starts at the Lynx and runs up the line, and the Bobcat sits below that point.
GTT’s Bobcat page gives its oxygen guidance as a ladder rather than a single number: runs well on a 5 LPM, 5 psi concentrator, optimal on 8 LPM, extremely well on 10 LPM or tanked oxygen. That one sentence names the smallest supply GTT considers a good fit, the supply it considers ideal, and tells you more oxygen keeps paying off above that.
Our catalog records the Bobcat’s oxygen minimum as 5 LPM, and that figure comes directly from this GTT sentence. It is GTT’s own statement of what runs the torch well, not a figure we measured or estimated.
Where the ~8.5 LPM figure comes from
The second number you will see for the Bobcat, on our torch page and in comparison tables, is ~8.5 LPM. It comes from GTT’s flow rate chart, which lists the Bobcat at 2.5 CFH of fuel and 18 CFH of oxygen at the largest usable flame on propane. Converting cubic feet per hour to liters per minute is a single multiplication (CFH x 0.4719 = LPM), and 18 CFH works out to roughly 8.5 LPM.
Three things about that figure are worth holding onto:
- It is the top of the range. The chart describes the biggest flame the Bobcat is meant to run, which on GTT’s Bobcat page is a flame of about 9/16 inch by 13 inches, enough for 1.5 inch solid boro. Most bench time is spent well below that, working beads or a small section of rod.
- It lines up with GTT’s own ladder. An 8.5 LPM ceiling sits right beside GTT’s “optimal on 8 LPM” line, which is what you would expect: an 8 LPM supply feeds nearly the full flame, and a 10 LPM supply or tanks feed all of it with room to spare.
- It is an estimate for sizing, not a spec to shop on. Oxygen draw moves with flame size, fuel pressure, and how you tune the torch.
The same chart gives the Bobcat’s pressures as fuel 1/4 to 5 psi and oxygen 5 to 10 psi (the Bobcat instruction sheet’s own starting settings are 5 psi propane and 10 psi oxygen), and GTT notes that natural gas consumption runs about 2.5 times the propane figure. That multiplier is about the fuel side, not oxygen, but it matters if you are planning a natural gas hookup: the Bobcat’s low fuel pressure floor is why it can run on unboosted household gas, and the fuel volume it draws will be higher than the propane line on the chart suggests.
The oxygen ladder at a glance
Here is GTT’s guidance laid out step by step, with what each supply level gives you in practice. The wording in the middle column is GTT’s; the right column is our reading of it.
| Oxygen supply | What GTT says | What that means at the bench |
|---|---|---|
| One 5 LPM, 5 psi concentrator | Runs well | Beads, soft glass and smaller boro work; the largest flame will be out of reach |
| 8 LPM concentrator | Optimal | Close to the full flame range; GTT’s recommended target |
| 10 LPM concentrator | Does extremely well | The full flame with headroom |
| Tanked oxygen | Does extremely well | The full flame with no supply ceiling; refills and cylinder handling instead |
For quick reference, the Bobcat’s other catalog facts:
| Field | GTT Bobcat |
|---|---|
| Mix | Surface mix (standard, not Triple Mix) |
| Jets | 7 |
| Oxygen (estimate, largest usable flame) | ~8.5 LPM |
| Price (GTT’s store) | $275 |
Running the Bobcat on one 5 LPM concentrator
This is the setup most first-time Bobcat buyers actually have, so it deserves a straight answer: yes, it works, and GTT says so. A single 5 LPM concentrator gives the Bobcat enough oxygen to run a working flame for beads, soft glass and small boro, which is most of what the torch is bought for.
What you give up is the top of the range. The chart’s largest usable flame wants more oxygen than a 5 LPM machine produces, so if you open the Bobcat all the way on one small concentrator, you are asking for flame the supply cannot feed. The symptoms are the familiar ones of an oxygen-starved torch: a softer, lazier flame that is slow to melt larger boro and may flutter as the concentrator struggles to keep up. The fix is not a different torch. It is either a smaller flame or more oxygen.
The limit shows up once the work moves toward the 1.5 inch solid boro and 3 inch boro pendants GTT describes the torch handling. Our oxygen concentrator LPM guide covers how to size a concentrator to a torch in more depth, including stacked setups.
Adding a second concentrator
The common upgrade path for a Bobcat owner who outgrows one 5 LPM machine is a second concentrator plumbed in parallel. That adds flow, not pressure: two units together deliver more liters per minute than one, but they do not raise the pressure at the torch. For the Bobcat that trade usually works out, because GTT’s own guidance is framed around a 5 psi concentrator and a higher flow target, and the chart’s oxygen pressure range for the Bobcat starts at 5 psi.
Why two small units are not interchangeable with one larger one for every torch is covered in how many LPM does my torch need. Confirm your concentrator’s real output with its maker.
Flashback protection on a concentrator setup
GTT’s flashback arrestor page says its arrestors need roughly 5 to 7 psi to open, and that they must not go on an oxygen concentrator’s output, where they may not open and can severely restrict flow. On a concentrator setup, GTT’s instruction is an arrestor on the fuel source, with a flame arrestor as the low-pressure device. That is the reverse of many generic checklists, and on a torch whose appeal is running well on a modest 5 psi supply, an arrestor that chokes the oxygen line would undo the point of the setup.
The right framing is the flashback protection your torch and your gas supply call for, following the instructions from GTT and from the maker of whatever protective device you fit. Our flashback arrestors guide explains what these devices do, where they sit, and how the surface-mix question differs from premix.
How the Bobcat compares with the Cricket and Lynx
The Cricket is GTT’s smaller standard surface-mix bench burner. Its chart figure is ~5.5 LPM at the largest usable flame, and GTT designed it specifically to get the best out of an economical 5 LPM, 5 psi concentrator. At $255 against the Bobcat’s $275, the Cricket is the torch built around a single small concentrator, while the Bobcat will run on one and does its best work with more. The full head to head is in GTT Bobcat vs GTT Cricket.
The Lynx is where GTT’s Triple Mix begins, and its chart figure is ~9.5 LPM. It has the same seven jets and single stage as the Bobcat. The Lynx adds a blue secondary-oxygen valve, GTT’s Triple Mix control. GTT rates it for solid boro up to 2 inches, where the Bobcat is rated to 1.5. On flow alone the two are close. Pressure is not: the chart lists the Lynx at 10 to 15 psi of oxygen and its instruction sheet at 15 to 25, both above the Bobcat’s 5 to 10, so check a concentrator’s output pressure before you plan a Lynx on it. The Lynx oxygen guide covers that case.
What this means if you are buying
If you already own a 5 LPM concentrator, the Bobcat is a torch that will run on it today and grow with you when you add oxygen later. If you are buying the whole setup at once and expect to work boro toward the top of the Bobcat’s range, budget for GTT’s optimal 8 LPM or a 10 LPM supply from the start, since that is what unlocks the full flame. Either way, settle the flashback protection question against GTT’s instructions for your specific supply before the first light.
Editor’s note: the 5, 8 and 10 LPM guidance and the flame and boro figures come from GTT’s own Bobcat page. The ~8.5 LPM figure is converted from GTT’s flow rate chart at the largest usable flame on propane and is an estimate for sizing, not a working-flame measurement. The price is from GTT’s own store as of our last check. Figures change, so confirm the current oxygen guidance, pressures and price with GTT before you buy, and follow your concentrator’s and arrestor’s own manuals where they are more specific.
Related guides
- How many LPM does my torch need?
- Oxygen concentrator LPM for lampworking
- GTT Bobcat vs GTT Cricket
- Flashback arrestors: does your glass torch need them?
Sources
- Glass Torch Technologies, Bobcat product page (5 LPM runs well, 8 LPM optimal, 10 LPM or tanks, flame and boro capacity): https://www.glasstorchtech.com/bobcat
- Glass Torch Technologies, Bobcat store listing (price): https://www.glasstorchtech.com/product-page/bobcat-1
- Glass Torch Technologies, Bobcat instruction sheet (starting regulator settings; PDF): https://www.glasstorchtech.com/_files/ugd/0f433e_ca86d174db4a40fe8bd70834dc70dea6.pdf
- Glass Torch Technologies, flashback arrestors (opening pressure, concentrator placement): https://www.glasstorchtech.com/flashback-arrestors
- Glass Torch Technologies, Flow Rate Chart (CFH figures at the largest usable flame, pressure ranges; PDF): https://www.glasstorchtech.com/_files/ugd/0f433e_940fa1536d544665a118116eb9542e62.pdf