How many LPM does your torch need? How oxygen demand scales with torch size and jets, where to find your spec, and how to map LPM to a supply that won't starve it.

How Many LPM Does My Torch Need? Sizing Oxygen for Your Glass Torch

Short answer: A torch’s oxygen demand, measured in liters per minute (LPM), scales with how big the torch is, how many (and how large) its jets are, and how hard you actually run it. Small beadmaking torches — a minor-class bench torch or a small surface-mix starter — sip oxygen and run happily on a modest supply. Large surface-mix and production boro torches are very thirsty and can demand far more than a single oxygen concentrator delivers, pushing you toward multiple concentrators plumbed in parallel or compressed tanks. The number you need is set by the torch you choose and the flame size you run — so size your supply to meet or exceed that demand with a little headroom.

This article is about demand: how much oxygen your torch wants and why. The companion piece, oxygen concentrator vs tanks for lampworking, covers supply: which source to run once you know your number. Read this one to figure out the target, then that one to choose how you’ll hit it.

What LPM actually measures

LPM is the volume of oxygen flowing to the torch each minute. A flame is just fuel and oxygen combusting; the more flame you want, the more of both gases you have to push through the torch. The oxygen side of that equation is what your supply has to satisfy, and it’s the side that usually becomes the bottleneck, because oxygen is the harder gas to produce or store in volume.

Every flameworking torch has a range of oxygen draw — a gentle, small flame uses little; the same torch opened up wide uses much more. So “how many LPM does my torch need” really means “how many LPM does my torch need at the flame size I intend to run.”

Why bigger torches need more oxygen: it’s the jets

The single best predictor of a torch’s appetite is its jets — the small orifices in the torch face where the gases meet and burn.

More jets means more points of combustion, so more total gas flows.
Larger jets pass more gas each.
More stages (multi-stage torches layer a center fire and outer rings of jets) stack additional jets you can bring online for a bigger, hotter flame.

A small single-stage bead torch might have a modest jet count and a correspondingly small oxygen appetite. A large multi-stage production torch has many jets across multiple rings, and when you light them all and open the flame up, the combined oxygen draw is several times that of the little torch. That’s the whole mechanism: more and larger jets, lit harder, equals more oxygen per minute. Source: GTT.

Mix type matters here too. If you’re weighing flame styles, see surface mix vs premix torches — but for sizing purposes, the thing that drives LPM is total jet capacity and how wide you run it, regardless of where the gases mix.

How to find your torch’s recommended LPM

The right source is the manufacturer’s spec sheet for your exact model. Reputable makers publish a recommended oxygen range (and often a fuel pressure) for each torch, and that’s the figure to design around.

A serious caveat, and we repeat it across this site: treat any single published LPM number as a starting point, not gospel. A torch’s real oxygen draw depends on flame size, fuel pressure, jet condition, and your specific configuration, and a lot of the LPM figures circulating on forums and spec lists are community-sourced and unverified. Our own catalog carries oxygen-LPM figures, and even those should be confirmed. Before you buy a supply around a number, confirm your exact torch’s oxygen requirement with the manufacturer. Source: Mountain Glass.

When you do find a figure, size for the top of your intended flame, not the minimum. If a torch is happy at, say, a modest flow for a small flame but wants much more wide open, and you plan to run it wide open, plan for the higher number plus headroom.

What happens when you run oxygen-starved

If your supply can’t deliver the LPM the flame is calling for, the torch doesn’t politely run smaller — it runs badly. An oxygen-starved flame is typically:

Lazy, cool, and lengthy instead of tight and hot,
Sputtering or fluttering as a concentrator’s internal tank empties and the sieve beds cycle,
Slow to melt boro or larger gathers, frustrating your work,
and sometimes sooty or unstable, never quite locking into a clean cone.

People often blame the torch when the real problem is supply. A powerful torch on inadequate oxygen performs worse than a modest torch that’s properly fed — which is exactly why we tell people to settle their oxygen reality before chasing a bigger torch. Source: Lampwork Etc..

Mapping LPM demand to a supply choice

Once you know roughly how many LPM your torch wants, you can map it to a supply. The full comparison lives in oxygen concentrator vs tanks for lampworking — here’s just enough to connect demand to options:

One oxygen concentrator typically delivers up to roughly 5–10 LPM, depending on the unit, and purity tends to sag as you push it toward its ceiling. That covers small and many mid torches.
Several concentrators plumbed in parallel add their flows together (two ~5 LPM units ≈ 10 LPM). Important: parallel plumbing adds flow, not pressure — concentrators are low-pressure devices and can’t simply be cranked up.
Compressed oxygen tanks deliver high flow at high, consistent purity on demand, which is what thirsty production flames need; the tradeoff is refills, handling, and high-pressure safety.
Bulk / liquid oxygen is for serious production where even banks of tanks become a chore.

The mapping is simply: demand at or below a single concentrator → one concentrator; demand a bit beyond that → two units or a modest cylinder; demand well beyond a concentrator’s reach → tanks, a bank, or bulk. Sources: The Crucible, Mountain Glass.

A qualitative guide by torch class

Because published per-model numbers are unreliable, the honest way to give guidance is by torch class, in ranges and unit counts rather than exact figures. Find roughly where your torch sits:

Torch class	Relative oxygen demand	Typical supply that comfortably feeds it
Small bead / minor-class bench torch, small surface-mix starter	Low	One concentrator
Mid-size bench surface-mix (versatile soft + small boro)	Moderate	One capable concentrator, sometimes two
Larger multi-stage surface-mix (pipes, functional, sculpture)	High	Multiple concentrators in parallel, or tanks
Large / production / scientific burners	Very high	Tanks, banks of cylinders, or bulk oxygen

Small / bead / minor class — low demand. These are the sweet spot for a single concentrator. This is the classic home-studio setup: one machine, no cylinders, work as long as you like. A versatile mid torch can also fall here — some are specifically known for running efficiently on a single ~5 LPM concentrator, which is part of why they’re such common first “real” torches. Confirm your model’s recommended LPM with the maker.
Mid bench surface-mix — moderate demand. Often a single capable concentrator, or a concentrator or two, depending on how big you run the flame. This is where people start plumbing units in parallel.
Large / production — high to very high demand. Big multi-stage boro and production torches can demand far more oxygen than one concentrator delivers. Here you typically need tanks, bulk oxygen, or a bank of several concentrators plumbed together. Trying to feed a large production flame from a single concentrator simply won’t work.

Source: Mountain Glass.

Notice we’re deliberately speaking in ranges and unit counts, not exact per-model LPM numbers. Published oxygen figures for specific torches are frequently unverified, and your real draw depends on flame size and fuel pressure. Get the spec from the manufacturer, then size with headroom.

Putting it together

Identify your torch class and, ideally, its manufacturer-published LPM range.
Pick the flame size you’ll actually run and size to the top of that, not the minimum.
Add headroom — a supply that’s always at its ceiling delivers a worse flame (and, for concentrators, worse purity).
Choose the supply that meets the number, using oxygen concentrator vs tanks.
Confirm everything with the maker before spending — this is the step that prevents an expensive mismatch.

This sequence is the third of the four questions in the glass torch buyer’s guide: decide your oxygen reality, then pick a torch that thrives on it.

Key takeaways

LPM demand scales with torch size, jet count/size, and how hard you run the flame — more and larger jets, lit wider, means more oxygen per minute.
Find your number on the manufacturer’s spec sheet — and treat any single published or community-circulated figure as a starting point to confirm with the maker.
Running oxygen-starved gives a lazy, sputtering, poorly performing flame — the torch gets blamed when the supply is at fault.
One concentrator ≈ up to ~5–10 LPM; add units in parallel for more flow (not pressure), or move to tanks/bulk for thirsty production torches.
Size by torch class and run the math toward your biggest intended flame, with headroom — then choose a supply that meets it.

Sources

Mountain Glass, “Best Torches for Lampworking or Glassblowing” — https://www.mountainglass.com/best-torches-for-lampworking-or-glassblowing
Glass Torch Technologies — https://www.glasstorchtech.com/
The Crucible, “Lampworking/Flameworking tools & supplies” — https://www.thecrucible.org/guides/lampworking-flameworking/tools-supplies/
Lampwork Etc., “Pre-mix vs Surface mix” — http://www.lampworketc.com/forums/showthread.php?t=191042

Editor’s note: torch oxygen demand and concentrator flow ranges reflect dealer and community information as of 2026; verify your specific torch’s recommended LPM and your supply options with the manufacturer before buying.