How to Evaluate Hydrogen Generators: 10 Questions Every Buyer Should Ask

FIRST QUESTION

Does the device separate the gases?

Splitting water produces hydrogen at one electrode and oxygen at the other, in roughly a two-to-one ratio. What happens next is one of the most important differences between hydrogen inhalation systems.

Separated systems keep the two gas streams apart, so the outlet delivers hydrogen alone. This is what a proton exchange membrane (PEM), also called a solid polymer electrolyte (SPE), is designed to do.

Unseparated systems collect both gases together as a mixture, sometimes marketed under names such as oxyhydrogen, HHO, or Brown’s Gas. In these devices roughly two-thirds of the output is hydrogen and one-third is oxygen.

This matters for a practical reason: most published hydrogen inhalation studies investigate molecular hydrogen delivered at a known concentration. If a device instead delivers a hydrogen-oxygen mixture, it may not match the gas composition used in that research. That doesn’t necessarily mean it is ineffective—it simply means the research may not be directly comparable.

Reading flow rate figures

Flow is usually given in milliliters per minute (mL/min) or liters per hour (lph). To compare figures, convert them to the same unit — 60 lph is 1,000 mL/min — and then establish what the number actually describes.

Total gas or hydrogen alone? On an unseparated device, a headline figure describes the combined mixture. Roughly a third of it is oxygen. A stated 833 mL/min of mixed gas is closer to 550 mL/min of hydrogen.

Production rate or delivered flow? Some specifications refer to gas generated inside the electrolyzer, while others describe gas available at the outlet. Ask which measurement is being reported.

Maximum or typical? Some figures describe peak output at the highest setting. Ask what the device delivers at the setting you would actually use, and whether output holds steady across a full session.

One user or two? A device rated for simultaneous users may divide its output between them. A figure quoted for the machine is not necessarily the figure reaching each person.

Measured under what conditions? Gas volume changes with temperature and pressure, so figures are ideally stated at standard temperature and pressure (STP). Backpressure from tubing, humidifiers, and cannulas can also reduce what reaches the user compared with what the cell produces.

Continuous or intermittent? Electrolysis generates heat, and output can fall as a cell warms up. Ask whether the unit is rated for continuous operation or needs a cool-down period between sessions, and what thermal protection it includes. This matters most in a clinic running back-to-back appointments.

Purity, and how it is verified

Purity describes what fraction of the delivered gas is hydrogen. A separated system should be able to state a specific figure, and that figure should come from laboratory measurement rather than from calculation or assumption.

A useful test of any manufacturer is simply to ask for the documentation behind the number. A company that measures purity can produce a report. If laboratory testing has not been performed, published purity figures may instead be based on theoretical calculations, internal measurements, or supplier specifications.

It is also worth asking how the device handles the oxygen produced at the other electrode. In a separated system that stream should be routed away from the hydrogen output by design, so ask whether the unit has a dedicated exhaust path and where it discharges.

If the device also makes hydrogen water

Dissolved concentration is a different measurement from gas flow rate. It is given in parts per million (ppm) or milligrams per liter (mg/L) and describes how much hydrogen is actually dissolved in the water — not how much gas passed through it. Bubbles rising through a glass are not the same as hydrogen in solution.

There is a physical ceiling worth knowing. At ordinary temperature and pressure, water saturates at roughly 1.6 mg/L of dissolved hydrogen. Figures well above that generally imply the water was pressurized or measured at the moment of production rather than at the moment of drinking.

Hydrogen also leaves an open container quickly — roughly half of it within about twenty minutes. A stated concentration means little without knowing when it was measured, which is why hydrogen water is best consumed immediately after it is made.

Electrolysis method and what it costs you

PEM / SPE. A solid membrane carries the current, so the device runs on distilled water alone. Water quality matters — dissolved minerals shorten membrane life, which is why these systems specify a low total dissolved solids (TDS) reading, usually <5 TDS.

Alkaline electrolysis. A dissolved electrolyte, commonly a hydroxide solution, carries the current instead. These systems require the operator to mix and periodically replace a caustic solution, and typically involve a scheduled rinse or flush.

Neither method is inherently unsafe. But they place different demands on whoever operates the machine. If a device ships with chemical handling equipment such as gloves and goggles, that is a signal about its maintenance routine. Ask what the ongoing consumables are, how often they are replaced, and what handling they require.

What certifications actually cover

Certification language is often used loosely. A few distinctions worth knowing:

CE marking on a device like this normally refers to electrical safety and electromagnetic compatibility — that the unit is electrically sound and does not interfere with other equipment. It is not a medical device approval, and it says nothing about health outcomes.

ISO 9001 is a quality management standard for how a factory runs. It is not the same as ISO 13485, which applies to medical device manufacturing. The two are sometimes conflated in marketing copy.

RoHS concerns restricted hazardous substances in the materials used. It is a materials compliance standard, not a performance or safety rating.

Two follow-up questions are worth asking about any certificate: which specific models does the document name, and which accredited laboratory issued it? Where a manufacturer tests one model and extends the result to others in a range, that is a normal and accepted practice — but it should be stated rather than left to inference. “Designed to meet” a standard is a description of intent, not evidence of testing.

READING THE CLAIMS

Language worth a second look

Molecular hydrogen has a substantial research literature, with well over a thousand peer-reviewed publications across cell, animal, and human studies. That makes it attractive territory for claims that go well past what has been studied. A few patterns are worth noticing:

Named conditions. Any suggestion that a wellness device diagnoses, treats, cures, or prevents a specific disease should be treated as a serious warning sign, regardless of how it is hedged, unless the device has received the regulatory clearance required to make those claims in your country.

Invented terminology. Proprietary terminology isn’t necessarily a warning sign, but if a scientific claim depends on a term that doesn’t appear in the scientific literature, it’s worth asking what independent evidence supports it.

Frequencies, resonance, and charged or structured water. Hydrogen gas is a simple molecule, and its studied effects are chemical. Claims involving frequencies, resonance, energy fields, structured water, or similar concepts are generally distinct from the published molecular hydrogen literature. If these claims are important to your purchasing decision, ask whether they are supported by peer-reviewed research specific to the device.

Unqualified superlatives. “The best” or “the most powerful” are comparative claims. Ask what the comparison is against and what measurement supports it.

Testimonials standing in for data. Personal accounts are not a substitute for measurement. A page rich in stories and thin on specifications is telling you something about what it can document.

Ownership questions people forget to ask

Warranty length and who backs it. A warranty is only as good as the party standing behind it. Ask how long it runs, whether the manufacturer or the seller honors it, and how service is delivered.

Terms of sale. Read them before ordering. Some devices are sold under terms restricting use to research or experimentation, which can matter a great deal if you intend to use the machine in a business.

Where it ships from. Cross-border orders can carry customs duties, brokerage fees, and complicated returns. Confirm who pays and what happens if you need to send the unit back.

Parts and support. Ask what happens in year two. Are replacement parts available, is there someone to call, and how are repairs handled?

THE SHORT LIST

Questions to ask any manufacturer

If you take nothing else from this guide, these ten questions will tell you most of what you need to know about any hydrogen inhalation device.

1. Does the outlet deliver separated hydrogen, or a hydrogen-oxygen mixture?
2. Is the stated flow rate total gas or hydrogen alone, and at which setting?
3. Is the unit rated for continuous operation, or does it need a cool-down between sessions?
4. What is the measured hydrogen purity, and which laboratory measured it?
5. Where is the oxygen stream vented?
6. What water does it require, and what are the ongoing consumables?
7. Which specific model numbers appear on the certification documents?
8. How long is the warranty, who backs it, and how is service delivered?
9. Do the terms of sale permit commercial or clinical use?
10. Where does it ship from, and who is responsible for duties and returns?

A manufacturer who knows their product can answer all ten quickly. How readily the answers come is often as informative as the answers themselves.