Oxygen Concentrator LPM for Lampworking: How Many LPM Does Your Torch Need?

Short answer: An oxygen concentrator is rated in liters per minute (LPM), and so is a torch’s oxygen appetite, so sizing one to the other is mostly a question of whether the machine’s LPM at usable pressure meets what the torch draws. The catch is that the torch number is a rough estimate, not a precise spec: it moves with flame size, tips, and how hard you push. A small surface-mix bench torch (a GTT Cricket or Carlisle Mini CC class) runs happily on a single 5 LPM concentrator, while a large multi-stage burner almost certainly will not, and needs stacked concentrators or tanks. Read your torch’s manual for the real requirement, treat every LPM figure below as approximate, and size the oxygen supply to the torch you actually run.

If you have not yet decided between a concentrator and cylinders at all, start with oxygen concentrator vs tanks for lampworking; this guide is the sizing layer on top of that decision.

How LPM matching actually works

A concentrator pulls oxygen out of room air and delivers it continuously, and its output is quoted in liters per minute. A torch’s oxygen demand is quoted the same way. Matching them is, in principle, straightforward: the concentrator’s LPM at the pressure your torch needs should meet or exceed the torch’s draw at the flame you actually run.

Two real-world wrinkles keep it from being pure arithmetic. First, pressure matters as much as flow. A concentrator delivers oxygen at low pressure, and a torch specified for a certain LPM assumes it arrives with enough push to feed the jets. Second, concentrator purity typically falls as flow rises. Community reports describe a unit rated for 5 LPM delivering roughly 95 percent oxygen at 4 LPM, around 90 percent at 4.5 LPM, and about 85 percent at its full 5 LPM. Those numbers are community knowledge, not a measured spec, but the direction is consistent: run a concentrator flat out and you get its maximum flow at its lowest purity, which is why headroom helps. Source: Lampwork Etc..

Oxygen is an estimate, not a precise spec

It is worth being blunt about this before you read a single number. Oxygen is the juice a torch burns, not a headline buying decision, and the LPM figures in our catalog are stored as estimates on purpose. Each torch page carries a single ~N LPM value labelled “Oxygen (estimate)”, derived from the manufacturer’s largest-usable-flame figure where we have one. It is not a guaranteed draw, and we never join it into a false min-to-max range that would imply precision we do not have.

So use these numbers to sort torches into rough tiers (sips, moderate, gulps), not to make a 5-versus-6 LPM purchasing call. The authority for what your specific torch needs is its own manual, and where a maker publishes a concrete concentrator requirement, we quote it as such below rather than leaning on the estimate.

Rough LPM by torch, small to large

Every torch below is surface mix, and the oxygen column is a rough estimate that resolves live from our catalog. Read it as tiering, not a spec sheet. Larger flames, hotter work, and pushing a torch hard all raise the real draw, and the maker’s manual is the final word.

A single 5 LPM concentrator lives at the top of that table and nowhere near the bottom. That is the whole point of the tiering, and it maps onto how the torches are built.

Surface-mix torches sip, big multi-stage burners gulp

The reason a beginner bench torch and a production burner sit so far apart on oxygen is architecture. A small surface-mix torch keeps a compact, efficient flame and asks for little oxygen. GTT designed the Cricket to get the best out of an economical 5 LPM, 5 psi oxygen concentrator, running on fuel-gas pressure as low as a quarter psi with about 3 psi oxygen. The Bobcat runs well on the same 5 LPM, 5 psi concentrator and reaches its optimal performance on an 8 LPM machine, again on fuel pressure as low as a quarter psi. Bethlehem draws the same line for its low-pressure surface-mix line: as long as a concentrator can produce a minimum of 5 LPM at 5 psi, it can feed the referenced Bethlehem torches, with the Bravo documented running household gas at a quarter psi alongside a concentrator supplying oxygen at 7 psi. The chemistry behind that floor is simple: one unit of propane needs roughly five units of oxygen for complete combustion. Sources: GTT Cricket; GTT Bobcat; Bethlehem Burners.

The big burners are a different animal. A GTT Cobra, GTT Delta Mag, or Herbert Arnold Zenit carries many more jets and a far larger flame, and its estimated oxygen draw is several times a small torch’s. No single small concentrator feeds one of those at full flame. If your ambitions run to large boro or production sculpture, the oxygen supply, not the torch, becomes the expensive and decisive part of the setup. Community consensus is consistent here: a small surface-mix bench torch in the Minor, Bobcat, or Mini CC class can run off a single 5 to 6 LPM concentrator, but a large torch almost certainly cannot run off one small machine. Source: Lampwork Etc..

For why surface-mix flames behave the way they do, see surface mix vs premix torches.

Single concentrator, stacked concentrators, or tanks

Once your torch outgrows a single concentrator, you have two ways forward.

Stack concentrators. Combining two or more machines with a Y-connector or manifold adds their LPM together, so two 5 LPM units give you about 10 LPM of flow. The important caveat is that the pressure does not add: the combined output sits at the pressure of the strongest single machine, not the sum, so matching the machines’ pressure output matters for a clean result. Stacking is how many home studios feed a mid-size torch without moving to cylinders, and it keeps the no-refills convenience of concentrators. Source: Lampwork Etc..

Move to tanks. Compressed oxygen cylinders can deliver higher flow than a stack of concentrators and work without mains power, which matters if outages are common where you are, since a concentrator is dead the moment the power is. If staying on concentrators is the plan, the other answer is a generator or battery station sized for the load, which backup power for a glass studio works through alongside the kiln half of the problem. The trade-off is that tanks run out and need refilling and transport, and bulk oxygen adds regulators, storage, and handling to your setup. For the full comparison of running costs, refills, and when the switch pays off, see oxygen concentrator vs tanks for lampworking. If you are shopping for specific machines, the oxygen concentrator brands compared guide covers what to look for.

Editor’s note: concentrator ratings, purity-versus-flow behavior, and stacking results vary by machine and by how it is plumbed. The figures here are manufacturer and community references as of 2026, not guarantees for your unit; confirm your torch’s oxygen requirement against its manual and your concentrator’s output against its own spec plate.

Flashback and flame arrestors with a concentrator

Sizing oxygen is also where a common safety mistake happens, so be precise about it. A conventional flashback arrestor is a pressure-actuated device, and GTT states directly that its arrestors need roughly 5 to 7 psi to open. A concentrator delivers oxygen below that, so an arrestor placed on a concentrator’s output may not open at all and will severely restrict the flow you just paid for.

GTT’s own guidance for a concentrator setup is therefore explicit: put the flashback arrestor on the fuel source, and use a flame arrestor, not a flashback arrestor, as the low-pressure device. GTT also distinguishes tank-style arrestors, the type used on glassworking torches to protect the tank and regulator, from the torch-style arrestors common on flame-cutting rigs, which are not the glassworking type. Do not fit a conventional arrestor to a concentrator’s oxygen output. Your torch and device manuals take precedence over any guide, and the full decision path is in flashback arrestors explained. Source: GTT flashback arrestors.

How to size your setup

Work backward from the torch you actually run, not the one you might buy someday:

1. Find the torch’s real requirement. If the maker publishes a concentrator spec, that is your number: the Cricket and Bobcat call for 5 LPM at 5 psi, Bethlehem’s referenced surface-mix line wants a minimum of 5 LPM at 5 psi. If there is no published concentrator figure, use the catalog estimate to place the torch in a tier and confirm against the manual.
2. Match flow at usable pressure. A single 5 to 6 LPM concentrator covers the sips tier. The moderate tier usually wants a bigger single unit or a stacked pair. The gulps tiers point at a large stack or tanks.
3. Leave headroom for purity. Because purity slides as flow climbs, sizing to run a concentrator flat out all day is the worst case; a little extra capacity keeps the oxygen cleaner and the flame steadier.
4. Fit the right arrestor in the right place. Flashback arrestor on the fuel source, flame arrestor as the low-pressure device, never a conventional arrestor on the concentrator output.

Not sure which tier your candidate torch lands in? The interactive torch finder lets you filter by oxygen estimate and mix type, and it flags when a filter is excluding models whose specs we do not have, so you are sizing against honest data. For the whole-system view, including fuel and budgeting, the complete glass torch buyer’s guide puts oxygen in context with everything else.

Key takeaways

• Concentrator output and torch demand are both measured in LPM, so sizing is a flow-at-pressure match, but the torch number is a rough estimate, not a precise spec.
• Small surface-mix torches sip: the Cricket and Bobcat run on a 5 LPM, 5 psi concentrator, and Bethlehem’s referenced surface-mix torches want a minimum of 5 LPM at 5 psi.
• Large multi-stage burners gulp: a Cobra, Delta Mag, or Zenit draws several times as much and will not run on one small concentrator.
• Stacking concentrators adds LPM but not pressure (the output sits at the strongest machine’s pressure); tanks give more flow and work without power but need refills.
• Never fit a conventional flashback arrestor to a concentrator output: it needs about 5 to 7 psi to open. Flashback arrestor on the fuel source, flame arrestor as the low-pressure device.
• Confirm your torch’s actual requirement against its manual, and treat every LPM figure here as approximate.

Related guides

• Oxygen concentrator vs tanks for lampworking
• Oxygen concentrator brands compared
• Flashback arrestors explained
• Surface mix vs premix torches
• Complete glass torch buyer’s guide

Sources

• Glass Torch Technologies, “Flashback Arrestors” (opening pressure, concentrator and flame-arrestor guidance): https://www.glasstorchtech.com/flashback-arrestors
• Glass Torch Technologies, “Bobcat” (5 LPM / 5 psi works, 8 LPM optimal, quarter-psi fuel): https://www.glasstorchtech.com/bobcat
• Glass Torch Technologies, “Cricket” (5 LPM / 5 psi concentrator, quarter-psi fuel, 3 psi oxygen): https://www.glasstorchtech.com/cricket
• Bethlehem Burners, “Common Glassworker Questions about Oxygen Concentrators” (5 LPM / 5 psi minimum, combustion ratio): https://www.bethlehemburners.com/news/oxygen-concentrator-questions/
• Bethlehem Burners, “Technical Information” (low-pressure surface-mix line): https://www.bethlehemburners.com/resources/technical-information/
• Lampwork Etc. (concentrator sizing, stacking, purity-versus-flow, community knowledge): https://www.lampworketc.com/forums/archive/index.php/t-107834.html
• David Clarke, “Using a DME Oxygen Concentrator for Lampworking” (artist reference, community knowledge): https://www.daclarke.org/ArsBrevis/oxyBoxen.html

Editor’s note: model behaviors and oxygen figures reflect public manufacturer pages and community sources as of 2026 and are approximate. Confirm your torch’s oxygen requirement and your concentrator’s output against their own documentation before buying or plumbing anything.