Portable hyperbaric chamber: soft shell vs hard shell, what 1.3 atmospheres actually delivers, and the weights nobody prints

“Portable” is the word the soft-chamber makers chose, and it is true the way a kayak is portable: the bag folds, the rest does not. What a buyer searching for a portable hyperbaric chamber is really choosing between is a soft shell at 1.3 to 1.5 atmospheres and a hard shell at 1.5 to 2.0, and the two differ in nearly everything: pressure, weight, standards, what the oxygen is doing, and what goes wrong. This page puts them side by side, then explains in numbers what the soft chamber’s dose, sold as mild hyperbaric oxygen therapy, actually is.

What “portable” means, in pounds

The makers’ own figures, read on 31 October 2026:

So the portable part is 26 to 55 lb, and the system is 100 to 125 lb where anyone has added it up. A 10 litre concentrator is a 40 lb box on wheels, a compressor another 40, and an inflated 33-inch bag is a 3 by 8 foot object in the room. It moves house; it does not go in a car for the weekend.

Soft shell hyperbaric chamber

A soft chamber is a bag of urethane-coated polyester or thermoplastic polyurethane with a long zipper, an internal frame to keep its shape, a mattress, windows, and ports for the air in, the relief valves, and the oxygen hose. A compressor outside pumps room air in; spring-loaded relief valves open at the set pressure, so the bag sits at 1.3 atmospheres (4.4 psi, Summit to Sea’s figure; OxyHealth says 4, OHS 4.3) or, on the newer imports, 1.4 or 1.5 (7.4 psi). You zip yourself in, or someone zips you, the pressure comes up over several minutes while you clear your ears, and you lie there for an hour.

Four things decide a soft chamber:

• Clearance. Summit to Sea’s Dive series (K072757, 2008) and the Newtowne Flexi-Lite lineage (K051759, 2005) are FDA-cleared, for one use, acute mountain sickness, on a physician’s order. OxyHealth claims clearance and publishes no number. OHS, OxyRevo, Airvida and Macy-Pan state none. The home chamber guide has the detail and the 2013 warning letter.
• Material and seams. OxyHealth specifies 44 oz urethane-coated polyester; Airvida TPU; the rest say little. The failure mode is the zipper and the seams, below.
• Oxygen. Every soft chamber is pressurized with air. Oxygen, if any, is a concentrator’s 90 to 95% stream through a mask, and the makers disagree by a factor of two about how much of it ends up in the bag.
• Life. No maker publishes a bladder service life or a cycle rating, and used ones sell at 35 to 60% of new, which is the market’s guess.

Hard shell hyperbaric chamber

A hard chamber is a pressure vessel: a steel or aluminum cylinder with acrylic or polycarbonate windows, a hinged or sliding door with a seal, and the pressure the vessel can hold decided by its engineering rather than a relief valve’s spring. Clinical monoplaces (Sechrist is the common make) are acrylic tubes rated to 3.0 atmospheres, filled with 100% oxygen, and stamped to ASME PVHO-1, the pressure-vessels-for-human-occupancy standard the FDA’s August 2025 letter names alongside NFPA 99.

The home hard shells are a newer thing. OxyRevo’s Quest36 is a 573 lb stainless and polycarbonate cylinder, 36 inches by 89, sold at $28,999 for 1.5 atmospheres and $29,999 for 2.0 at its dealers on 31 October 2026, with a 10 litre concentrator feeding a mask and two cooling units; its Space60 sitting chamber reaches 2.0 at $34,999 to $35,999; Airvida lists an “Ultra” hard shell to 2.0 at $27,999 to $29,999; Macy-Pan sells 1.6 to 2.0 atmosphere hard shells with no public price and a disclaimer that they are not medical devices. OxyRevo claims CE, ISO and TÜV certifications and neither an FDA clearance nor a PVHO stamp. OxyHealth’s Fortius 420, a 1,250 lb vessel to 4.0 atmospheres with a hood for 100% oxygen, is the clinical-grade exception at $136,100.

The force is the reason the stamp matters. At 2.0 atmospheres the vessel holds 14.7 psi over the room. On a 36-inch door that is about 1,000 square inches and 15,000 lb of force on the seal and hinges, every session, for the life of the chamber. A PVHO stamp means an engineer signed for that; a CE mark on a Chinese import means a conformity declaration. Both 2025 chamber deaths were in hard chambers, and the Michigan one was a stamped, cleared, code-compliant clinical chamber, which is the point: the vessel was not what failed.

Soft shell vs hard shell, line by line

Mild hyperbaric oxygen therapy: what 1.3 atmospheres delivers

“Mild” or “mHBOT” is the industry’s word for a soft-chamber session, and it is accurate. Oxygen gets to tissue almost entirely on hemoglobin, which is already about 97% full at sea level. Pressure adds oxygen the only other way, by dissolving it in plasma, in proportion to the partial pressure of oxygen in the lungs. That pressure is the fraction of oxygen you breathe times the total pressure, less the 47 mmHg of water vapor in your airway. Dissolved oxygen is about 0.0031 mL per deciliter of blood per mmHg.

Resting tissue draws about 5 mL of oxygen from every deciliter of blood that passes. At 2.0 atmospheres on pure oxygen, the plasma alone carries most of that, which is why a hospital chamber can keep a crushed limb alive with its blood supply damaged. A soft chamber on air adds about 0.15 mL per deciliter, three percent of what tissue uses; with a mask, maybe 0.4. In plain terms, a 30% mask at 1.3 atmospheres is what a 37% mask would give you at sea level, in bed.

Three things follow, and the trials bear each out:

1. The DoD used the soft-chamber dose as its placebo. The HOPPS and BIMA concussion trials put their sham groups in 1.2 atmospheres of air, and in HOPPS the sham group improved as much as the 1.5 atmosphere oxygen group. Proponents read that as pressurized air working; the investigators read it as placebo. Either reading means a home bag has not been shown to do what the oxygen arm did.
2. The one time 1.3 atmospheres was the treatment, it did not hold up. Rossignol’s 2009 autism trial at 1.3 atmospheres and 24% oxygen reported more “much improved” ratings than a 1.03 atmosphere control; Granpeesheh’s 2011 replication at the same dose found no consistent effects, and the Cochrane review found one trial of 60 children with no improvement and more ear barotrauma.
3. Nobody has tested it for what it is sold for. We found no trial of a 1.3 atmosphere chamber for muscle recovery, sleep, energy, jet lag or aging. Two tiny crossover studies, ten people each, measured mood after cycling and blood pressure at rest. That is the literature.

The oxygen question, and why it is also the fire question

The bag is filled with air. The concentrator makes 90 to 95% oxygen at 10 litres a minute and sends it down a hose to a mask or cannula. What you breathe depends on the mask seal, and what leaks around it goes into the bag, where it accumulates for an hour in a sealed volume of about 100 cubic feet with a compressor adding air and the valves bleeding the mix out. The makers’ statements about the result: OxyHealth, the room oxygen does not change; Macy-Pan, 24%; one spec sheet we found, no more than 25%; OHS, 40%; Summit to Sea, nothing. Nobody shows a measurement.

That number is the dose, since it decides whether you are on the 1.3× or the 1.9× row above. It is also the fire line: NFPA 99 defines an oxygen-enriched atmosphere as anything over 23.5% oxygen by volume and requires grounding and material controls above it, and Health Canada’s June 2026 advisory names the concentrator as what makes a soft chamber a fire risk.

Ears, and an hour in a bag

At 4.4 psi your eardrums feel what a diver’s do at 10 feet. In hospital chambers, middle-ear barotrauma is the commonest side effect, 43% of patients in one center’s series, nearly all mild; in the healthy-volunteer cognition trial at 2.0 atmospheres, 4 of 30 had it. A soft chamber is a quarter of that squeeze and still a squeeze: the makers tell you to swallow, yawn or pinch and blow on the way down, and to stop and vent if it hurts. A cold or blocked sinus is a reason to skip the session. Confinement anxiety is reported in about 2% of clinic patients; a 27-inch bag is tighter than any clinic chamber, which is why the 32 to 40 inch sizes exist and cost more. Plan on 60 to 90 minutes, which is what the makers and the studios sell, with the compressor running beside you the whole time; Airvida claims 50 dB or less, and nobody else publishes a figure.

What we have not measured

Every weight, pressure and wattage here is a maker’s. The measurements this page owes are the same five as the home chamber guide’s, and the first two matter most: a calibrated gauge on the port of a soft chamber through a session, because 1.3 atmospheres is the valve’s rating and we have never seen a trace; and a diver’s oxygen analyzer in the bag and at the mask over an hour, with and without the concentrator, because that one reading is both the dose row above and the fire line. Then a power meter, a sound meter and a stopwatch on the time to pressure. One chamber, one afternoon, n=1.

Where that leaves a buyer

If you want the dose the trials used, it is 2.0 atmospheres on 100% oxygen in a stamped vessel with someone outside, which is a clinic, at the prices in the cost guide. If you want a soft chamber for what it is, a third more oxygen pressure on air and about twice with a mask, in a bag that folds, the cleared ones are Summit to Sea’s and Newtowne’s, on a prescription, and the home chamber guide has the market and the circuit. If you want 2.0 atmospheres at home, ask the seller for the PVHO stamp and read the benefits guide first, because the trials at that dose are smaller and less sham-controlled than the price suggests. Our how we test page says what every figure here is and is not.